Thinking about a starter system, but no south facing roof

glocklt4glocklt4 Solar Expert Posts: 29
I've been reading through a lot of the info posted here (which is amazing and very detailed - great!).

I'm intrigued by solar and am considering a starter system for our house here in Dallas now that we've got some disposable income and I like to tinker. Maybe 200-400watt and I'd like to have enough battery storage to run two laptops, our wireless router, FiOS modem, CCTV system (4 cam), and a small pump in our aquarium for a few days at a minimum if power goes out (during those days with no grid power I'd hope to generate some power too, of course, but as long as the batteries + charging would last 3-4 days with these devices that would be fine). When not using it for emergency power due to a blackout, I would probably just plug random appliances into the inverter on one-off instances. My computer equipment, aquarium, and other things more than likely draw too much power. Also, during Xmas it would be great to run our Xmas lights off of the batteries for 5-6 hours a night and say that it's all a "green" system (though this may require switching to LED lights as much as I like the warm color of incandescent!). I have a Kill-A-Watt and will hook it up to all of these appliances to identify the power requirements, but I am stuck before I even start... (i think).

I only have a very small spot on my roof that is South facing, ugh. 80-90% of my roof is West or East. The good news (maybe), is that our West facing horizon is very wide, and we are elevated from the neighborhood across the West, so we get unobstructed sun all the way until the sun sets (well, maybe a few minutes before due to houses a half mile away, but way more than most homes would). The ray intensity is obviously not as great as it sets, but maybe having a wide horizon there will be of saving grace. I do not want to have to install panel mounts that face South on the West facing roof (it's probably against my HOA anyway, and I need to check on putting a couple panels up flat on the roof as it is).

So my question ... should I even consider solar with an inadequate South facing roof? Would our West facing roof end up providing enough sunlight to make up for this? I know that there is no definitive answer to this without taking measurements of everything, but I figure you guys here have enough experience after everything I've read to quickly make a recommendation to proceed or not. At a minimum I want to get a panel I could put out on the roof outside my office (also facing west but only direct sun from noon to sunset) if we lose power and use that just to charge devices for emergency. That kind of an emergency system would probably only be 50-100watt.

Here is our roof setup:

Attachment not found.

I am just completely guessing, but it appears the slope of the roof is around 40-45 degrees, which is great in winter for Dallas (32.7deg latitude), but in summer when we have plenty of sun that would be too steep of an incline I believe.

Attachment not found.
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Comments

  • AceNZAceNZ Solar Expert Posts: 104 ✭✭✭✭
    Re: Thinking about a starter system, but no south facing roof

    A west-facing roof isn't a deal killer; you will probably take a 15 to 20% hit compared to south-facing. It's not ideal, but you will still get afternoon sun. As long as you don't have persistent shading (from poles, trees, chimney, etc), you should be OK.

    Having a full off-grid subsystem generally does take considerable effort and expense beyond just mounting a few panels, though.
  • BB.BB. Super Moderators, Administrators Posts: 29,366 admin
    Re: Thinking about a starter system, but no south facing roof

    Use PV Watts to estimate the "Ideal" vs the actual possible panel orientations.

    To "save money" with solar--Grid Tied is the way to go (solar panels + GT Inverter connected to the house mains). HOWEVER--If there is a power failure, the solar panels are useless (as everything in solar/engineering, there are exceptions with limitations).

    An off grid system (unplug from the grid) will cost you (very roughly) ~5-10x your average utility power pricing--And you have to pay much of the money up front, and have major costs every 5-10 years for new batteries, etc...

    And there are "Hybrid" Inverters--Basically a combination of the two above. Use the utility to "bank power" when the grid is up, and use your batteries (plus AC inverter) to run the house when the grid is down... Very nice, but still pretty expensive.

    If you have long power outages (weeks to months), a Hybrid system may be nice (unless the hurricane or tornado blew off your panels).

    Otherwise, for short term outages (several days to a week or two)--A genset is hard to beat (and you still need a backup genset for off grid and possible hybrid system backup to the backup).

    Yes, you can install 2-4 "golf cart" batteries and a few hundred watts of solar panels... And it will give you nice lighting, run a laptop, charge your cell phones, etc.... But it will probably not run your refrigerator. That takes a bigger system (and more money).

    Before you start--Measure your loads, define your needs, and do a few paper designs (we will help you with that). And see what makes sense for you.

    And--Before you install a major solar power system--Highly suggest you go through a do "extreme conservation"--In general, it is cheaper to conserve power than to generate it. And, usually, conservation improvements (insulation, double pane windows, high efficiency heat pumps, etc.) have a better resale value too if you ever sell the home.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Thinking about a starter system, but no south facing roof

    i should add that it is not a law that pvs must go on a roof. now i'm not sure which is west or east on your pic or how high southerly obstructions may be, but you can pole mount pvs.
  • SolInvictusSolInvictus Solar Expert Posts: 138
    Re: Thinking about a starter system, but no south facing roof

    The aerial view of the house probably has north at top and east to the right.

    When the roof faces east and west, one solution is to put equal numbers of PV panels on both faces of the roof. You could also mount some PV panels on the south facing wall to capture sunlight during Autumn and Winter.

    From PV Watts using Fort Worth, the optimal direction for fixed tilt is:
    Array Tilt: 32.9 degrees
    Array Azimuth: 180.0 degrees



    Month
    Solar Radiation, optimal, 32.9 deg & 180 deg (kWh/m2/day)
    Solar Radiation, east, 45 deg & 90 deg (kWh/m2/day)
    Solar Radiation, west, 45 deg & 270 deg (kWh/m2/day)


    1
    4.32
    2.66
    2.77


    2
    4.77
    3.37
    3.33


    3
    5.50
    4.27
    4.51


    4
    5.98
    5.16
    5.51


    5
    6.02
    5.85
    5.79


    6
    6.25
    6.17
    6.62


    7
    6.39
    6.48
    6.30


    8
    6.31
    5.87
    5.79


    9
    5.83
    4.80
    4.83


    10
    5.56
    3.86
    4.08



    11
    4.43
    2.88
    2.90


    12
    4.10
    2.46
    2.52


    year:
    5.46
    4.49
    4.59


    Tilting them to 45 degrees with east and west azimuths decrease average annual power output to 82% for east and 84% for west relative to the optimal direction. Your worst month for power output would be in December for the east facing PV panels, 2.46 kWh/m2/day, which is 2.46 / 4.10 = 60% reduction relative to the optimal direction. You would need to overbuild the PV array by about 1.67 times to get minimum power equivalent to pointing it in the optimal direction. Otherwise you make do with less power during Autumn and Winter. PV Watts accounts for sunrise, sunset, pointing direction, haze and clouds but not for shading from terrestrial objects.
  • glocklt4glocklt4 Solar Expert Posts: 29
    Re: Thinking about a starter system, but no south facing roof
    AceNZ wrote: »
    A west-facing roof isn't a deal killer; you will probably take a 15 to 20% hit compared to south-facing. It's not ideal, but you will still get afternoon sun. As long as you don't have persistent shading (from poles, trees, chimney, etc), you should be OK.

    Having a full off-grid subsystem generally does take considerable effort and expense beyond just mounting a few panels, though.

    Thanks for the info about the west-facing roof. That's good to hear that it's not a deal killer. The North end of the West roof is completely unobstructed all the way to sunset, but the South end of the West roof might get a little shade from a large tree for the last hour to sunset.

    Yes, after reading the details of everything for an off-grid subsystem, I am not trying to achieve this at all. We go through too much power with A/C here in Dallas to accomplish this. I'm not ready for the kind of investment that would take. I'm thinking mostly just for emergency blackout use and periodic appliances that would not take too much power for the inverter/batteries.
  • glocklt4glocklt4 Solar Expert Posts: 29
    Re: Thinking about a starter system, but no south facing roof
    BB. wrote: »
    Use PV Watts to estimate the "Ideal" vs the actual possible panel orientations.

    To "save money" with solar--Grid Tied is the way to go (solar panels + GT Inverter connected to the house mains). HOWEVER--If there is a power failure, the solar panels are useless (as everything in solar/engineering, there are exceptions with limitations).

    An off grid system (unplug from the grid) will cost you (very roughly) ~5-10x your average utility power pricing--And you have to pay much of the money up front, and have major costs every 5-10 years for new batteries, etc...

    And there are "Hybrid" Inverters--Basically a combination of the two above. Use the utility to "bank power" when the grid is up, and use your batteries (plus AC inverter) to run the house when the grid is down... Very nice, but still pretty expensive.

    If you have long power outages (weeks to months), a Hybrid system may be nice (unless the hurricane or tornado blew off your panels).

    Otherwise, for short term outages (several days to a week or two)--A genset is hard to beat (and you still need a backup genset for off grid and possible hybrid system backup to the backup).

    Yes, you can install 2-4 "golf cart" batteries and a few hundred watts of solar panels... And it will give you nice lighting, run a laptop, charge your cell phones, etc.... But it will probably not run your refrigerator. That takes a bigger system (and more money).

    Before you start--Measure your loads, define your needs, and do a few paper designs (we will help you with that). And see what makes sense for you.

    And--Before you install a major solar power system--Highly suggest you go through a do "extreme conservation"--In general, it is cheaper to conserve power than to generate it. And, usually, conservation improvements (insulation, double pane windows, high efficiency heat pumps, etc.) have a better resale value too if you ever sell the home.

    -Bill

    Thanks, Bill. Great advice all around. The biggest way for us to conserve energy here in Dallas is by turning the temps up during Summer, but convincing the wife to run fans off of a solar system instead of running the A/C at lower temps is a lost cause :). I'm not entirely aiming to save money. Power during a blackout is priceless though when you're a computer nerd like myself. Our longest power outage has only been about a day, and that was due to a microburst (if you're not familiar with storms, it's basically straight line winds that can hit 100mph). It took out major power lines everywhere that took a while for the elec company to get back going. Also a few weeks ago we were very lucky to still have power after the huge ice storms here. Many people, including my family not far away, lost power for 3-4 days. The ice was so bad that you couldn't get out of your house to drive anywhere if needed. As a programmer, if I've got power I can do my job anywhere, so it's very necessary. I have a pretty large bank of APC batteries here at the house hooked into a server, the CCTV and external hard drives, but obviously those will only last so long. In the event of a blackout that we could expect to be down for an extended period of time, it would be extremely nice to have a way to generate more power than what I can store around the house stacking up batteries that are trickle charging from the grid all the time. I have considered a generator, but if I had one I would really only use that in true emergency mode since it's fossil fuel based. We don't go camping or do other things that often that would require power away from the house that we'd use a generator for either. So while a generator would meet the emergency need, if I had solar, I'd be more inclined to go out of my way and plug appliances into it knowing that by doing so it's "free" energy. I can certainly afford any electric bill that we could run up at our house, and could go buy a $1k gas generator at home depot in the morning and be done with it, but solar is much more intriguing and I would like to learn about it.

    As for other ways to conserve first, we do plan to upgrade windows in the house in the future, but not at this time. We have a lot of them, and it would run around $25k. We would expect a good amount of savings in HVAC due to this though (maybe 15-20%). Thanks to vaulted ceiling all over our 2 story house, it's very difficult for us to do more insulation.
  • glocklt4glocklt4 Solar Expert Posts: 29
    Re: Thinking about a starter system, but no south facing roof
    niel wrote: »
    i should add that it is not a law that pvs must go on a roof. now i'm not sure which is west or east on your pic or how high southerly obstructions may be, but you can pole mount pvs.

    The google satellite pic is orientated with North up. I should have added a compass to the image to make that more clear. I do understand that pole mount would be an option, however I do not think that's nearly as aesthetically pleasing. I've also considered putting panels on our arbor on the deck in the rear of the house (which you can see west of the house), however there is a large tree there that continues to grow and would probably block a good amount of the sunlight needed, especially in the winter. Also the arbor is not in the best shape due to a bit of land movement down our hill in the back, so I don't want to add anything on top of it. Pole mount at the lower part of our very sloped west side would be out of our view possibly, but i'm still not sure what the HOA and other HOA behind us would say. Also, as the panels go lower in the "valley" to the west of us, the less direct sunlight it would get as the sun sets (of course I could make up for that by pointing the panels so the South, and maybe even get more than west only facing panels on the much higher roof.
  • glocklt4glocklt4 Solar Expert Posts: 29
    Re: Thinking about a starter system, but no south facing roof
    The aerial view of the house probably has north at top and east to the right.

    When the roof faces east and west, one solution is to put equal numbers of PV panels on both faces of the roof. You could also mount some PV panels on the south facing wall to capture sunlight during Autumn and Winter.

    From PV Watts using Fort Worth, the optimal direction for fixed tilt is:
    Array Tilt: 32.9 degrees
    Array Azimuth: 180.0 degrees



    Month
    Solar Radiation, optimal, 32.9 deg & 180 deg (kWh/m2/day)
    Solar Radiation, east, 45 deg & 90 deg (kWh/m2/day)
    Solar Radiation, west, 45 deg & 270 deg (kWh/m2/day)


    1
    4.32
    2.66
    2.77


    2
    4.77
    3.37
    3.33


    3
    5.50
    4.27
    4.51


    4
    5.98
    5.16
    5.51


    5
    6.02
    5.85
    5.79


    6
    6.25
    6.17
    6.62


    7
    6.39
    6.48
    6.30


    8
    6.31
    5.87
    5.79


    9
    5.83
    4.80
    4.83


    10
    5.56
    3.86
    4.08



    11
    4.43
    2.88
    2.90


    12
    4.10
    2.46
    2.52


    year:
    5.46
    4.49
    4.59


    Tilting them to 45 degrees with east and west azimuths decrease average annual power output to 82% for east and 84% for west relative to the optimal direction. Your worst month for power output would be in December for the east facing PV panels, 2.46 kWh/m2/day, which is 2.46 / 4.10 = 60% reduction relative to the optimal direction. You would need to overbuild the PV array by about 1.67 times to get minimum power equivalent to pointing it in the optimal direction. Otherwise you make do with less power during Autumn and Winter. PV Watts accounts for sunrise, sunset, pointing direction, haze and clouds but not for shading from terrestrial objects.

    Thanks for the description of this information. I did go to that site earlier today and viewed this chart (maybe not the East/West though), but I wasn't completely sure what to make of it.

    Great idea about having one set facing east and one facing west. I suppose that if I really only plan to run a few panels, the small South facing area may be enough, but I have not gotten on the roof to measure. 2nd story roofs are not my favorite thing to get up on :). From other reading I've done on here, I would need micro-inverters or multiple strings in order to do panels facing different directions, right? Unless all of them get the same sunlight, then the panel with the least light will bring down the power of the entire array? I'd prefer not to have multiple since I'm trying to just go with a rather simple setup.
  • BB.BB. Super Moderators, Administrators Posts: 29,366 admin
    Re: Thinking about a starter system, but no south facing roof

    It is all about the loads.... Just to give you an idea of scale:
    • 1 kWH per day (1,000 WH)--Small cabin with lights, laptop, radio, small water pump for pressurization.
    • 3.3 kWH per day (100 kWH per month)--Add refrigerator, clothes washer, well pump (a very efficient/small off grid home with near-normal electric life)
    • 10 kWH per day (300 kWH per month)--An efficient home with a refrigerator + freezer, several computers.
    • 33 kWH per day (1,000 kWH per month)--The US average power usage, light A/C, electric hot water.
    • 100 kWH per day (3,000 kWH per month)--Living in Dallas with full A/C and Heat pump, computer servers, etc.
    If you want a "small" starting system... Say 1,000 WH per day, 4 hours of sun, 120 VAC power (i.e., operate a laptop+modem+desk lamp type system) using "nominal" design for full off grid use (just to keep this short and sweet):
    • 1,000 WH per day * 1/12 volt battery bank * 1/0.85 inverter eff * 2 days of no sun storage * 1/0.50 max battery discharge = 392 AH 12 volt battery bank
    Or around 4x 6 volt @ 200 AH golf cart batteries.

    To charge batteries, we recommend 5% to 13% rate of charge--5% for low usage system, 10% rate of charge or more for daily cycling:
    • 392 AH * 14.5 volts charging * 1/0.77 panel+charge controller derating * 0.10 rate of charge = 738 Watt array (based on battery size and 10% rate of charge)
    And we need to figure out 1,000 Watt*Hours per day based on hours of sun you have available... For a south facing array, 4 hours of sun minimum is a good start (bad weather, you will need back up power source, or simply turn stuff off until the sun returns):
    • 1,000 WH per day * 1/0.52 end to end system eff * 1/4 hours of sun per day minimum = 481 Watt Array (based on sun and average load)
    Of course, you should never plan on 100% of predicted power per day (probably 66% to 75% would be a better number)--But you can use a genset to make up for bad weather (and emergency backup).

    For this mythological system, a 481 watt to 738 watt solar array would be a pretty good fit, and you could go a bit larger too (0.13 rate of charge would be ~995 Watt array "cost effective" maximum...

    A nice AC inverter for this size system would be a MorningStar 300 Watt TSW 12 VDC inverter... It also has remote on/off and search mode for easy control and automatic start (>~6 watts of 120 VAC, unit will turn "on").

    Anyway--Just some quick math and numbers... You can see that a 10 kWH per day system is getting pretty large (and expensive--Equivalent of 80 "golf cart" batteries and ~5kW-10kW solar array). And that is probably a fraction of what your home uses today.

    Energy usage is a highly personal set of choices--We try to help people understand/design a system that will meet their needs--In as cost effective manner as possible.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Re: Thinking about a starter system, but no south facing roof
    glocklt4 wrote: »
    Great idea about having one set facing east and one facing west.

    Do a search on "virtual tracking" or "virtual tracker" for lots more info on east/west arrays. --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • glocklt4glocklt4 Solar Expert Posts: 29
    Re: Thinking about a starter system, but no south facing roof
    BB. wrote: »
    It is all about the loads.... Just to give you an idea of scale:
    • 1 kWH per day (1,000 WH)--Small cabin with lights, laptop, radio, small water pump for pressurization.
    • 3.3 kWH per day (100 kWH per month)--Add refrigerator, clothes washer, well pump (a very efficient/small off grid home with near-normal electric life)
    • 10 kWH per day (300 kWH per month)--An efficient home with a refrigerator + freezer, several computers.
    • 33 kWH per day (1,000 kWH per month)--The US average power usage, light A/C, electric hot water.
    • 100 kWH per day (3,000 kWH per month)--Living in Dallas with full A/C and Heat pump, computer servers, etc.
    If you want a "small" starting system... Say 1,000 WH per day, 4 hours of sun, 120 VAC power (i.e., operate a laptop+modem+desk lamp type system) using "nominal" design for full off grid use (just to keep this short and sweet):
    • 1,000 WH per day * 1/12 volt battery bank * 1/0.85 inverter eff * 2 days of no sun storage * 1/0.50 max battery discharge = 392 AH 12 volt battery bank
    Or around 4x 6 volt @ 200 AH golf cart batteries.

    To charge batteries, we recommend 5% to 13% rate of charge--5% for low usage system, 10% rate of charge or more for daily cycling:
    • 392 AH * 14.5 volts charging * 1/0.77 panel+charge controller derating * 0.10 rate of charge = 738 Watt array (based on battery size and 10% rate of charge)
    And we need to figure out 1,000 Watt*Hours per day based on hours of sun you have available... For a south facing array, 4 hours of sun minimum is a good start (bad weather, you will need back up power source, or simply turn stuff off until the sun returns):
    • 1,000 WH per day * 1/0.52 end to end system eff * 1/4 hours of sun per day minimum = 481 Watt Array (based on sun and average load)
    Of course, you should never plan on 100% of predicted power per day (probably 66% to 75% would be a better number)--But you can use a genset to make up for bad weather (and emergency backup).

    For this mythological system, a 481 watt to 738 watt solar array would be a pretty good fit, and you could go a bit larger too (0.13 rate of charge would be ~995 Watt array "cost effective" maximum...

    A nice AC inverter for this size system would be a MorningStar 300 Watt TSW 12 VDC inverter... It also has remote on/off and search mode for easy control and automatic start (>~6 watts of 120 VAC, unit will turn "on").

    Anyway--Just some quick math and numbers... You can see that a 10 kWH per day system is getting pretty large (and expensive--Equivalent of 80 "golf cart" batteries and ~5kW-10kW solar array). And that is probably a fraction of what your home uses today.

    Energy usage is a highly personal set of choices--We try to help people understand/design a system that will meet their needs--In as cost effective manner as possible.

    -Bill

    Yeah, we are definitely on higher end of your scale. The past month was 1109 kWH. In summer we are between 2400-2600kWH for July-Sept. This is with two 3-ton A/C systems. One system was recently completely replaced, but the other is still original, 22 years now. We're just waiting on it to die before replacing. The replacement system dropped our elec bill about $30-50/mo during the summer, and $20/mo in winter. The lowest we've ever used is 900kWH in one month in a Feb a couple years ago that was pretty warm (heater fan not running much). Our top power sucking devices are certainly the server and other computer electronics that are always on (though some devices shut themselves down for a while), the fish tank (salt water aquarium with multiple pumps and 400watts of lights that are on 10-11 hours a day), TV DVR's sitting around the house (1 with harddrive always on, 3 with no harddrive), 1 large fridge/freezer combo, and then we have two plasma TV's (one 58" that has to have 4 fans to run, one 50" that uses probably half that). Also our water heater is elec and changing that over to gas would be very difficult since there is no venting for exhaust gases and it sits right in the middle of the house in the garage. I do keep the temperature at a minimum compared to stock setting. I have looking into switching to tankless and it's amazing how much power those things need when they are on. Overall we would save a decent amount of power if we switched I believe (since it's just the wife and me that take showers once a day, and then dish & clothes washers that use hot water every few days, plus some hand dish washing). So that tank of water is staying hot for little use compared to a family with kids. Anyway, my thought is still definitely not to try and add supply to the house with a grid-tie system, since we just use too much here. Conservation and replacing the 2nd HAVC system is definitely the better way to lower our bills.

    The types of battery systems you've proposed seem reasonable to me. While you recommend "golf cart" batteries, I would be OK with investing in decent 12v deep cycle batteries unless the 6V are significantly cheaper and work just as well. I will get to measuring loads on everything today to see if 1,000WH would be sufficient. Based on your calculation of almost 400AH in batteries and almost 500-700W of PV array, I would guess that I would end up spending around $2-3k on this system with the prices of seen on components. I did read about Morning Star inverters and they look great. Would it be ok to increase to a higher wattage inverter though for the instances where I use this system to plug in random appliances? Obviously it would drain the batteries faster if I pull more watts, but I think that would be ok (of course not going below 50% battery use).

    One of the main ways I plan to fund this system is through Amazon credit. They have Renogy 100W panels for a good price ($160) and they have great reviews. Are these considered an acceptable panel to use? http://smile.amazon.com/RENOGY-Monocrystalline-Photovoltaic-Battery-Charging/dp/B009Z6CW7O/ref=sr_1_2?ie=UTF8&qid=1388248324&sr=8-2&keywords=renogy

    Also are Tracer brand charging controllers good? They have a 20A MPPT for $130 that seems like a good value: http://smile.amazon.com/Tracer-2210RN-Charge-Controller-Regulator/dp/B008KWPH12/ref=sr_1_2?ie=UTF8&qid=1388182347&sr=8-2&keywords=mppt+charge+controller

    One additional question I have is about placement of batteries compared to panels (specifically the distance). If I did a roof mount on my west facing roof, that's the opposite end of the house from my garage where I would assume is the best place to store the batteries.
  • BB.BB. Super Moderators, Administrators Posts: 29,366 admin
    Re: Thinking about a starter system, but no south facing roof

    Don't pick your hardware just yet... Battery banks have a nasty tendency to last 2x longer if you spend 2x the amount of money (in general) and another habit of owners "murdering" their first bank or two until they get the hang of operating a solar power system and performing maintenance.

    "Cheap" golf cart batteries will last 3-5 years, and expensive fork lift/other high end batteries will last ~10-15+ years. You have the choice of flooded cell (more rugged/forgiving/longer life and cheaper) or AGM (sealed, less acid misting, cleaner, less sulfur smell, 2x more expensive)... etc. (lots of battery choices).

    We tend to recommend "cheap" batteries for a first bank. Especially for learning how systems works and figuring out the eventual system you will want (don't buy a 20 year battery that you will have to trash in 3 years when you redesign the system).

    Second, batteries need good solar panels and charge controllers... You don't want to go "low end" on your major components. You should expect 20+ years from your solar array and 10+ years from your charge controllers/AC inverters. High end controllers also offer far more control (and data logging/other options) than low end hardware.

    Start with sizing a system for your needs--After the rough paper design is done, then you pick hardware for your needs (solar power system design is a lot of mix and matching to your needs/system design. It is very difficult to scale up or down designs without needing to replace much of the hardware).

    Make no bones about it--A 1,000 WH per day is a small system. And a ~300-600 Watt AC inverter is about all that makes sense. You can pick battery types that support higher surge currents (AGM for example) and install a larger AC inverter--But then you will have the "typical" UPS that you see around--It will supply power for 30 minutes and allow you to either start your backup generator and/or to safely shut down your computer systems.

    The typical off grid solar power system is designed to supply power for 24 hours per day for ~2 days without sun (such as during stormy weather when you lose AC mains or for an off grid home where there is no AC power). That means your average loads need to be very small/efficient. Just plugging a standard Energy Star rated refrigerator will use around 1.2 to 2+ kWH per day. Way more than a 1,000 WH per day (1 kWH per day) system can supply for two days.

    Many off grid folks will design a solar power system to supply their "base loads" and use a generator to run shop tools, etc. Solar power is expensive, and backup solar power to utility mains is even more so (most people find that the difference between full off grid solar and just using a backup genset is something like >9 months a year of power usage).

    Or, such as in your case, the solar supplies a few LED lights in the home, a laptop computer, plus recharging some cell phones and, perhaps a water pump to pressurize you home plumbing. I.e., allow you to "survive" with some comfort and 24 hour a day electricity for a few weeks/months until power is restored. Perhaps using a genset to fill a cistern/pump to a large pressure tank a couple times a day (or a week) for water.

    Just running a genset can cost you $1 per kWH -- And full off grid solar can be $1-$2+ per kWH (assuming 20 year system life, replacement battery bank and electronics, off grid using power 9-12 months a year)--compared to the $0.10 to $0.20 per kWH you are probably paying for utility power.

    If your $200 per month utility bill was $2,000 to $4,000 per month instead--Would you do anything different on power usage in your home?

    Regarding your overall power needs. Grid Tied solar can save you money--It depends on what your power rates are (in California, we can see $0.40 to $0.50+ per kWH for summer afternoons for heavy power users). Utility polices for Grid Tied systems (billing plans) also have a huge impact on return of investment too (and many smaller/co-op utilities will refuse GT solar systems).

    Some random thoughts--The battery bank + charge controller + AC inverter should be mounted next to each other--You can send power from the solar array to the charge controller, and 120/240 VAC power out the longer distances. The 12/24/48 VDC runs need to be kept short and heavy cabling (in general).

    If you have natural gas, that can help reduce heating/hot water costs... However, the newer heat pump systems give natural gas a run for its money.

    And a heat pump water heater (like GE Geospring and others) will give "cold/dry air" as a waste product--Plus it is 2-3 times more efficient than standard resistance based water heaters. Also, mini-split type air sourced heat pump systems are giving central air/heating a run for its money. Both in price and efficiency. We have some members here that run mini-splits and heat pump water heaters on their off grid power systems (smaller homes, well insulated, etc.).

    Another issue is appliance efficiency in your home... If you can reduce AC power usage in your home, you will save on A/C costs too. Pretty much 100% of the AC power you dump into your home (refrigerators, cooking, computers, entertainment systems, lighting, etc.) all eventually turns into heat--And you have to pay to move the heat from inside the house outside.

    Some light reading:

    http://www.windsun.com/Batteries/Battery_FAQ.htm
    http://www.batteryfaq.org/
    http://batteryuniversity.com/

    And here is a thread with a bunch information on various solar and conservation links:

    Working Thread for Solar Beginner Post/FAQ


    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • solar_davesolar_dave Solar Expert Posts: 2,343 ✭✭✭✭
    Re: Thinking about a starter system, but no south facing roof

    Bill is speaking the gospel here.

    We have a 12.5 Kw grid tie solar system and at the time we installed it was $6+ a watt installed for a total of about $80K. We were fortunate at the time to hit the sweet spot in rebates, from the utility @ $3 a watt and the balance had a 30% fed tax credit and a $1000 state tax credit. These days systems can be installed for about $4 a watt. Even with our large system we did some extreme conservation efforts, new air source heat pumps with about double the seer rating, added insulation, CFL/LED lighting, Energy Star appliances, replaced the pool pump with a VFD, switched to gas cook top etc. ect.

    Even with all that we are not net zero on the electric bill but have reduced our annual utility cost by about 90%. What is key is to know and understand the utility net metering plan and how that works with a TOU plan as well. Run the numbers to see how long your ROI is, on our case we got a payback in about 3 years, most get a 5-10 year payback. BTW we are fortunate that our utilities are all underground and in the 15 years we have been here I can only remember a 2 hour outage one time, so very reliable utility power.

    Also be aware that your internet provider may on stay alive for a day or so during a massive outage.

    ILFE PM me for a picture, attached.
  • techntrektechntrek Solar Expert Posts: 1,372 ✭✭✭
    Re: Thinking about a starter system, but no south facing roof

    A few thoughts. Forget new windows, save your money. Window replacement companies have over-hyped "high efficiency" replacement windows and won't save you the $ you think they will. Single-pane windows are rated about R-1 in insulative value, double-panes are R-2 to R-3. The best windows won't be above R-5. When you consider the total area the windows cover and the minor increase in R value, your $25k would be better spent elsewhere. One suggestion I heard on another forum is to have an extra pane added on the outside of every window (basically a custom storm window), but you must be careful to either not add this to one window in each bedroom, or make sure they are installed so they can be removed in an emergency - a "code" thing for emergency egress. Personally I wouldn't bother. I would spend the money on more insulation everywhere else.

    As for hot water, your best payback will be to add a solar thermal system to supply your needs, much better than switching to a gas or heat-pump water heater. A few thousand dollars and it will break even in just a few years. Increase the solar thermal system 50% and stick it on one of your west-facing roofs, even in a place where it may get some partial shading (unlike solar PV which doesn't like partial shading).

    If you keep your current electric water heater put a timer on it. For $50-75 it will break even in less than a year. I have one and only have it set to come on for a few hours in the evening and a few hours in the morning when we are likely to take showers. I found a 5-10% drop in my electric bill after installing it. On the weekend if we get up late we'll flip it on a half hour before we begin showers, but usually that isn't necessary since the water heater has a high thermal carryover. I wrapped it with 6 inches of fiberglass insulation all-around which improved that.
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
  • BB.BB. Super Moderators, Administrators Posts: 29,366 admin
    Re: Thinking about a starter system, but no south facing roof

    You will find lots of differences of opinions--And most of them are correct for the people writing them.

    For me, I had several old homes that either had no insulation, or at best some in the attic. I installed my own double pane vinyl windows and have been very happy with them.

    In one home, a small 1950's 3 bedroom California Rancher with a couple west facing bedrooms (no wall insulation, some attic insulation, stucco walls). I took out old wood double hung windows and replaced with double pane, low-E, vinyl windows and the sunny summer afternoon temperatures dropped by 20F in that part of the house--And we could not really "feel" the difference between the shaded vs sunny side (no A/C, no central heat at the time).

    Home was vacant for a while, and I found the temperatures in the home averaged probably from 55 to 60 degrees (no power/heating, locked up tight)--And it was always "cold". Open some windows, turn on some appliances, and it started getting warm (at equalizing with outside temperatures) pretty quickly.

    Have a 1930's home (wood ship-lap siding) we live in now--took out the wall board, insulated, installed double pane windows, new doors with double pane widows/fixed weather stripping--And now a house that would "roast" in summer afternoons (and be freezing in winter) now almost needs a tad of (natural gas) heating on some summer days (very little solar gain if the windows are closed). We also use CFL/LED lighting which reduced waste heat too in bedrooms/kitchen (no A/C).

    Have a friend that had a "cold" and "expensive" home to heat on top of a windy hill nearby. House was probably less than 20 years old, was well insulated and had single pane windows. I suggested they look at window replacement. Last I talked with them, they did not see a big reduction in heating costs, but did find the house was much quieter/less dusty--So to agree with "techntrek"--Window replacements are not a panacea either.

    The choice between a heat pump water heater (if you already have A/C + heat pump, adding a de-superheater) may be almost "free" water heating for much of the year (waste heat from A/C system).

    I too keep looking at solar hot water--But it can be a bit of a plumbing nightmare. In climates with occasional hard freezes, you either have to weep a bit of water, drain back, or anti-freeze based systems (to prevent freeze damage), a circulating pump+controller+surge tank+heat exchangers. They can be definitely an education in plumbing and servicing. Still makes sense--But do some research (and call references) before you open your wallet (true for pretty much any major project).

    In the Working FAQ thread, there are some links to various solar projects.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • glocklt4glocklt4 Solar Expert Posts: 29
    Re: Thinking about a starter system, but no south facing roof
    BB. wrote: »
    Don't pick your hardware just yet... Battery banks have a nasty tendency to last 2x longer if you spend 2x the amount of money (in general) and another habit of owners "murdering" their first bank or two until they get the hang of operating a solar power system and performing maintenance.

    "Cheap" golf cart batteries will last 3-5 years, and expensive fork lift/other high end batteries will last ~10-15+ years. You have the choice of flooded cell (more rugged/forgiving/longer life and cheaper) or AGM (sealed, less acid misting, cleaner, less sulfur smell, 2x more expensive)... etc. (lots of battery choices).

    We tend to recommend "cheap" batteries for a first bank. Especially for learning how systems works and figuring out the eventual system you will want (don't buy a 20 year battery that you will have to trash in 3 years when you redesign the system).

    Second, batteries need good solar panels and charge controllers... You don't want to go "low end" on your major components. You should expect 20+ years from your solar array and 10+ years from your charge controllers/AC inverters. High end controllers also offer far more control (and data logging/other options) than low end hardware.

    Start with sizing a system for your needs--After the rough paper design is done, then you pick hardware for your needs (solar power system design is a lot of mix and matching to your needs/system design. It is very difficult to scale up or down designs without needing to replace much of the hardware).

    Make no bones about it--A 1,000 WH per day is a small system. And a ~300-600 Watt AC inverter is about all that makes sense. You can pick battery types that support higher surge currents (AGM for example) and install a larger AC inverter--But then you will have the "typical" UPS that you see around--It will supply power for 30 minutes and allow you to either start your backup generator and/or to safely shut down your computer systems.

    The typical off grid solar power system is designed to supply power for 24 hours per day for ~2 days without sun (such as during stormy weather when you lose AC mains or for an off grid home where there is no AC power). That means your average loads need to be very small/efficient. Just plugging a standard Energy Star rated refrigerator will use around 1.2 to 2+ kWH per day. Way more than a 1,000 WH per day (1 kWH per day) system can supply for two days.

    Many off grid folks will design a solar power system to supply their "base loads" and use a generator to run shop tools, etc. Solar power is expensive, and backup solar power to utility mains is even more so (most people find that the difference between full off grid solar and just using a backup genset is something like >9 months a year of power usage).

    Or, such as in your case, the solar supplies a few LED lights in the home, a laptop computer, plus recharging some cell phones and, perhaps a water pump to pressurize you home plumbing. I.e., allow you to "survive" with some comfort and 24 hour a day electricity for a few weeks/months until power is restored. Perhaps using a genset to fill a cistern/pump to a large pressure tank a couple times a day (or a week) for water.

    Just running a genset can cost you $1 per kWH -- And full off grid solar can be $1-$2+ per kWH (assuming 20 year system life, replacement battery bank and electronics, off grid using power 9-12 months a year)--compared to the $0.10 to $0.20 per kWH you are probably paying for utility power.

    If your $200 per month utility bill was $2,000 to $4,000 per month instead--Would you do anything different on power usage in your home?

    Regarding your overall power needs. Grid Tied solar can save you money--It depends on what your power rates are (in California, we can see $0.40 to $0.50+ per kWH for summer afternoons for heavy power users). Utility polices for Grid Tied systems (billing plans) also have a huge impact on return of investment too (and many smaller/co-op utilities will refuse GT solar systems).

    Some random thoughts--The battery bank + charge controller + AC inverter should be mounted next to each other--You can send power from the solar array to the charge controller, and 120/240 VAC power out the longer distances. The 12/24/48 VDC runs need to be kept short and heavy cabling (in general).

    If you have natural gas, that can help reduce heating/hot water costs... However, the newer heat pump systems give natural gas a run for its money.

    And a heat pump water heater (like GE Geospring and others) will give "cold/dry air" as a waste product--Plus it is 2-3 times more efficient than standard resistance based water heaters. Also, mini-split type air sourced heat pump systems are giving central air/heating a run for its money. Both in price and efficiency. We have some members here that run mini-splits and heat pump water heaters on their off grid power systems (smaller homes, well insulated, etc.).

    Another issue is appliance efficiency in your home... If you can reduce AC power usage in your home, you will save on A/C costs too. Pretty much 100% of the AC power you dump into your home (refrigerators, cooking, computers, entertainment systems, lighting, etc.) all eventually turns into heat--And you have to pay to move the heat from inside the house outside.

    Some light reading:

    http://www.windsun.com/Batteries/Battery_FAQ.htm
    http://www.batteryfaq.org/
    http://batteryuniversity.com/

    And here is a thread with a bunch information on various solar and conservation links:

    Working Thread for Solar Beginner Post/FAQ


    -Bill

    Good point about using some cheaper batteries for a first system in case I fry them. I had read that somewhere else about how overcharging or over discharging can easily kill them. Read a lot into the physics of the batteries to understand why. If there are any good sources for these 6V batteries to wire up in series instead at a good price, please let me know. 3-5 years for the first set is fine as I dial everything in and learn about the system in general.

    Yes, agree to getting quality panels, controller, and inverter. Agree and understand that sizing up later is difficult, so that's why I'm trying to think about what I'd like to accomplish now. Besides the morning star inverter, if there is any other hardware you can recommend, please do so. If I can get it from Amazon, that's a nice bonus.

    The 300-600 watt inverter for use when we are in black out mode does seem appropriately sized (and I'll confirm that for my appliances), but the reason I ask about a larger would be if I do want to use some kind of appliance off of the system that takes a bit more power for a short time. Just to be sure that it would be physically possible without hurting the batteries. I do understand what you're saying that it becomes equivalent to a typical computer system UPS with short run time, but again this would be for use when not in emergency mode. I also understand that if I drain the batteries down to 50% with a higher watt appliance like this I have just lost my backup system until it charges back up completely. A risk I'll have to take if I want to hook up non-emergency power load equipment for a short time.

    It's worth noting again that we very rarely have had power issues, but the recent ice storm brought the possibility to my mind. If there's some way to generate power at all, it's a win in my book as I have no way to do so right now. I only have UPS battery backups.

    Our power rates fluctuate as we are in a co-op. Usually it runs between $0.10-$0.14/kWH. Solar at 10-20x's that is ok with me for this use.

    As far as distances to the devices, that's what my concern was going to be. My father was an EE and I learned quite a bit from him. I know that DC needs large gauge wire and should not go long distances, but A/C is fine for longer distances. If I put panels on the North West roof, it sounds like I would need to have my battery bank directly below that. My only options then would be to have the battery bank, controller and inverter outside the house in weather proof storage. We get quite the swing in temperatures here throughout the year (15-115 deg F), so I'm not sure that is even possible outside. If I were to put some panels on the only South facing portion of our roof, that the DC lines could run directly along the outside of the house and come through the wall over near my grid meter, and into the garage there. This seems much more logical. It's possible that I could even run the DC lines through the roof if I can get access to that area but I don't have access to the garage from the 2nd story attic, so the battery bank, controller and inverter would have to be in the attic. I'm not sure that is very safe either with 140+ deg temps in the summer up there. Any suggestions on location for all of this?

    I wasn't aware there are heat-pump water heaters. That's interesting. I will read into those and keep that in mind when our water heater goes out eventually. I believe our current one is about 10 years old now, so it probably has 5-8yrs left on it.

    Yes, very good point on AC use going down also reducing A/C use. Our 58" plasma puts off considerable heat, which has to be sucked right back out of the house by HVAC. When we replace the TV we will probably go with LCD to reduce this heating effect. Other appliances do the same of course.

    Thanks again for all of your comments, it's great info to think about.
  • glocklt4glocklt4 Solar Expert Posts: 29
    Re: Thinking about a starter system, but no south facing roof
    solar_dave wrote: »
    Bill is speaking the gospel here.

    We have a 12.5 Kw grid tie solar system and at the time we installed it was $6+ a watt installed for a total of about $80K. We were fortunate at the time to hit the sweet spot in rebates, from the utility @ $3 a watt and the balance had a 30% fed tax credit and a $1000 state tax credit. These days systems can be installed for about $4 a watt. Even with our large system we did some extreme conservation efforts, new air source heat pumps with about double the seer rating, added insulation, CFL/LED lighting, Energy Star appliances, replaced the pool pump with a VFD, switched to gas cook top etc. ect.

    Even with all that we are not net zero on the electric bill but have reduced our annual utility cost by about 90%. What is key is to know and understand the utility net metering plan and how that works with a TOU plan as well. Run the numbers to see how long your ROI is, on our case we got a payback in about 3 years, most get a 5-10 year payback. BTW we are fortunate that our utilities are all underground and in the 15 years we have been here I can only remember a 2 hour outage one time, so very reliable utility power.

    Also be aware that your internet provider may on stay alive for a day or so during a massive outage.

    ILFE PM me for a picture, attached.

    Nice system! Some great rebates you were able to get too. Quite amazing. 90% reduction is a pretty great success.

    Good point about the internet service provider. I do not know where our local fiber station is, but they will have a limited amount of battery backup there if they are affected as well. Luckily I do have a data plan with tethering on my ATT iPhone, which works great. So as long as the cell towers stayed up, then that would be a backup. After that, not much I can do, and at that point I have a pretty good excuse to the boss as to why I cannot work. Of course there are things I can work on without an internet connection as a programmer :).
  • glocklt4glocklt4 Solar Expert Posts: 29
    Re: Thinking about a starter system, but no south facing roof
    techntrek wrote: »
    A few thoughts. Forget new windows, save your money. Window replacement companies have over-hyped "high efficiency" replacement windows and won't save you the $ you think they will. Single-pane windows are rated about R-1 in insulative value, double-panes are R-2 to R-3. The best windows won't be above R-5. When you consider the total area the windows cover and the minor increase in R value, your $25k would be better spent elsewhere. One suggestion I heard on another forum is to have an extra pane added on the outside of every window (basically a custom storm window), but you must be careful to either not add this to one window in each bedroom, or make sure they are installed so they can be removed in an emergency - a "code" thing for emergency egress. Personally I wouldn't bother. I would spend the money on more insulation everywhere else.

    As for hot water, your best payback will be to add a solar thermal system to supply your needs, much better than switching to a gas or heat-pump water heater. A few thousand dollars and it will break even in just a few years. Increase the solar thermal system 50% and stick it on one of your west-facing roofs, even in a place where it may get some partial shading (unlike solar PV which doesn't like partial shading).

    If you keep your current electric water heater put a timer on it. For $50-75 it will break even in less than a year. I have one and only have it set to come on for a few hours in the evening and a few hours in the morning when we are likely to take showers. I found a 5-10% drop in my electric bill after installing it. On the weekend if we get up late we'll flip it on a half hour before we begin showers, but usually that isn't necessary since the water heater has a high thermal carryover. I wrapped it with 6 inches of fiberglass insulation all-around which improved that.

    Interesting info about the windows, and good point. My parents had their house windows redone a few years ago and I actually don't think I've discussed what kind of energy savings they have received from that. I'll have to ask. I definitely agree that insulation would be a better way to go, but we really just don't have much area in our attic that is even reachable to insulate further. My Aunt and Uncle built their own house in Tulsa recently and they went with 2x6 studded walls that allowed them to use a much higher R value wall insulation. With excellent windows and other great insulation, their energy bills are very low. They would be a great candidate for solar to eliminate their probably max 1-1.5kWH/mo bill, but this is all way too complicated for them even if they paid someone to do everything :).

    I haven't given much thought to solar water heating. I'll do some more reading into that to see if I'd like to pursue that some day. Thanks for the tip.

    Thank you for reminding me about the timer on our water heater. It has been broken for years now and I just have not taken the time to fix it. It got stuck on and never turned off the water heater. The previous owners of the house installed it. It's about time to get that fixed :).
  • glocklt4glocklt4 Solar Expert Posts: 29
    Re: Thinking about a starter system, but no south facing roof
    BB. wrote: »
    You will find lots of differences of opinions--And most of them are correct for the people writing them.

    For me, I had several old homes that either had no insulation, or at best some in the attic. I installed my own double pane vinyl windows and have been very happy with them.

    In one home, a small 1950's 3 bedroom California Rancher with a couple west facing bedrooms (no wall insulation, some attic insulation, stucco walls). I took out old wood double hung windows and replaced with double pane, low-E, vinyl windows and the sunny summer afternoon temperatures dropped by 20F in that part of the house--And we could not really "feel" the difference between the shaded vs sunny side (no A/C, no central heat at the time).

    Home was vacant for a while, and I found the temperatures in the home averaged probably from 55 to 60 degrees (no power/heating, locked up tight)--And it was always "cold". Open some windows, turn on some appliances, and it started getting warm (at equalizing with outside temperatures) pretty quickly.

    Have a 1930's home (wood ship-lap siding) we live in now--took out the wall board, insulated, installed double pane windows, new doors with double pane widows/fixed weather stripping--And now a house that would "roast" in summer afternoons (and be freezing in winter) now almost needs a tad of (natural gas) heating on some summer days (very little solar gain if the windows are closed). We also use CFL/LED lighting which reduced waste heat too in bedrooms/kitchen (no A/C).

    Have a friend that had a "cold" and "expensive" home to heat on top of a windy hill nearby. House was probably less than 20 years old, was well insulated and had single pane windows. I suggested they look at window replacement. Last I talked with them, they did not see a big reduction in heating costs, but did find the house was much quieter/less dusty--So to agree with "techntrek"--Window replacements are not a panacea either.

    The choice between a heat pump water heater (if you already have A/C + heat pump, adding a de-superheater) may be almost "free" water heating for much of the year (waste heat from A/C system).

    I too keep looking at solar hot water--But it can be a bit of a plumbing nightmare. In climates with occasional hard freezes, you either have to weep a bit of water, drain back, or anti-freeze based systems (to prevent freeze damage), a circulating pump+controller+surge tank+heat exchangers. They can be defiantly an education in plumbing and servicing. Still makes sense--But do some research (and call references) before you open your wallet (true for pretty much any major project).

    In the Working FAQ thread, there are some links to various solar projects.

    -Bill

    Man, I envy those whole have cool houses all year round. We really get hot here in Dallas summers lately :).

    Interesting about a heat pump in HVAC system that would take the heat from the house and put it into the hot water supply. That's a great idea!

    Agree that solar hot water may be a big pain. I don't know much about it, but I have seen it on some houses around here. I'll read a bit to see if I want to pursue that at all. Hard freezes would definitely be an issue here. 3 weeks ago we couldn't leave the house for 4 days here with sub freezing temps and a solid sheet of ice 2-4" thick over everything. Anti-freeze closed loop system sounds like a pain, and I have a decent amount of plumbing experience.

    Thanks again to all of you for the great information. This is really helpful!
  • BB.BB. Super Moderators, Administrators Posts: 29,366 admin
    Re: Thinking about a starter system, but no south facing roof
    glocklt4 wrote: »
    If there are any good sources for these 6V batteries to wire up in series instead at a good price, please let me know. 3-5 years for the first set is fine as I dial everything in and learn about the system in general.
    Flooded cell batteries are expensive to ship--So, many times, a local battery supplier (even your Walmart, Costco, etc.) can be the best bank for your buck (make sure batteries are new mfg--And have not been sitting around for months uncharged).
    Yes, agree to getting quality panels, controller, and inverter. Agree and understand that sizing up later is difficult, so that's why I'm trying to think about what I'd like to accomplish now. Besides the morning star inverter, if there is any other hardware you can recommend, please do so. If I can get it from Amazon, that's a nice bonus.

    Much of the solar stuff is really application/size specific. There are some great 15 and 30 amp controllers out there... But there are also larger (upwards of 60-90 amp) that have amazing amounts of configuration and even Internet connectivity.

    Rogue 30 Amp MPPT controller (very nice smaller MPPT unit)
    Midnite Classic (very nice high amperage unit with some very interesting programming and even battery shunt monitor option)

    I really like to do the "Paper Design/Requirements" first--Then look at a the "class" of controller that will meet those needs and see which fits your needs best.

    Our host, Northern Arizona Wind & Sun started this forum and keeps the lights on here. The day to day moderation and posting is all the work of volunteers (just like you)--So, we try to point at www.solar-electric.com first. However, we do not ask/worry about whom you purchased the hardware from.

    Similar for AC inverters... There are just a huge range of devices out there. Including some very nice Inverter/Chargers. Some which can integrate with both AC mains and AC gensets at the same time (basically, a whole house UPS). 120 or 120/240 VAC, Off Grid, Grid Tied, or Hybrid (GT+Off Grid capable).

    Remember that everything revolves around conservation. A small MorningStar 300 watt inverter uses 0.6 watt on standby and 6 watts while running. You throw a 2,000-6,000 Watt TSW AC inverter out there, and you may burn 20-60+ watts just when the inverter is "ON". An Energy Star full size fridge may use ~42 watts average 24 hours per day (365 kWH per year).

    Are you into computer/remote monitoring? Need to run a 240 VAC well pump? Need to parallel several inverters together for more power (even three phase power)? Like to charge from AC mains directly (internal battery charger)?

    By the way, a Battery Monitor (like a tri-metric), is very nice for day to operation of your bank and understanding what is going on.
    The 300-600 watt inverter for use when we are in black out mode does seem appropriately sized (and I'll confirm that for my appliances), but the reason I ask about a larger would be if I do want to use some kind of appliance off of the system that takes a bit more power for a short time. Just to be sure that it would be physically possible without hurting the batteries. I do understand what you're saying that it becomes equivalent to a typical computer system UPS with short run time, but again this would be for use when not in emergency mode. I also understand that if I drain the batteries down to 50% with a higher watt appliance like this I have just lost my backup system until it charges back up completely. A risk I'll have to take if I want to hook up non-emergency power load equipment for a short time.
    It's worth noting again that we very rarely have had power issues, but the recent ice storm brought the possibility to my mind. If there's some way to generate power at all, it's a win in my book as I have no way to do so right now. I only have UPS battery backups.

    A natural gas genset would not be a bad idea... For my home, I use a Honda eu2000i (1,600 watts) as my loads are pretty small (on average). And you can get ones converted to propane/natural gas. Only uses ~1-2 gallons of gasoline per day for my backup power.

    For rare outages, a genset is not a bad deal. Don't go bigger than you need (you can easily get 8-10kW gensets), but the bigger genset can use 1 gallon per hour or more--So having a fuel supply like natural gas or a large tank of diesel/propane is needed for these large gensets.
    As far as distances to the devices, that's what my concern was going to be. My father was an EE and I learned quite a bit from him. I know that DC needs large gauge wire and should not go long distances, but A/C is fine for longer distances. If I put panels on the North West roof, it sounds like I would need to have my battery bank directly below that. My only options then would be to have the battery bank, controller and inverter outside the house in weather proof storage. We get quite the swing in temperatures here throughout the year (15-115 deg F), so I'm not sure that is even possible outside. If I were to put some panels on the only South facing portion of our roof, that the DC lines could run directly along the outside of the house and come through the wall over near my grid meter, and into the garage there. This seems much more logical. It's possible that I could even run the DC lines through the roof if I can get access to that area but I don't have access to the garage from the 2nd story attic, so the battery bank, controller and inverter would have to be in the attic. I'm not sure that is very safe either with 140+ deg temps in the summer up there. Any suggestions on location for all of this?

    Actually, for home sized system, AC vs DC current really does not matter (AC is easier to step up/step down with a simple transformer--DC needs electronics to do the same thing--But these days, MPPT--Maximum Power Point Tracking--Controllers that can efficiently down converter from high voltage/low current arrays to low voltage/high current for the battery bank.
    I like to suggest a 100 amp nominal current is about "big enough" for DC wiring... 100 amps * 12 volts = 1,200 watt nominal AC inverter. 24 volt is 2.4 kW inverter, over that, look at 48 volt battery bank. MPPT charge controllers are current rated--So 60 amps at 12 volts or 48 volts is about the same for the charge controller--But you can support a 4x larger solar array with the 48 volt battery bank vs 12 volts on a single controller.

    An insulated building can work fine. digging down a few feet in the earth can work well to moderate temperature swings too.

    Put Batteries+Charge Controllers+AC inverters in the same location/area. Install solar array remotely and/or AC power remote to home. Usually remote panels are a bit better idea (battery bank+balance of system close to home for service/monitoring is better).

    Running a "higher voltage array" (Vmp~100 VDC or more for some controllers) allows you to use much smaller gauge wiring from array to charge controller and no voltage drop/regulation issues (MPPT charge controller will accept a wide rate of voltage/current from solar array).

    In general, a 400 watt or smaller array can usually use a PWM controller (less expensive, but array cabling needs to be short). And 800 Watt or larger array generally is better supported with the more expensive MPPT type charge controller.
    I wasn't aware there are heat-pump water heaters. That's interesting. I will read into those and keep that in mind when our water heater goes out eventually. I believe our current one is about 10 years old now, so it probably has 5-8yrs left on it.

    You can get whole house and sub-circuit monitors (like this one) and figure out how much power you are using for the home and major loads.

    A Geospring costs something like $1,000 (SWAG). You might pay that back in as little as a couple years (at 1/2 the electrical usage, can you save $50 per month?)--And if you can make use of the "waste" cold/dry air--even reduce your A/C usage more (note, in cold climates, some folks need external air to keep from over cooling the room--and below ~55F or so, they do have internal resistance heaters to help).
    Yes, very good point on AC use going down also reducing A/C use. Our 58" plasma puts off considerable heat, which has to be sucked right back out of the house by HVAC. When we replace the TV we will probably go with LCD to reduce this heating effect. Other appliances do the same of course.

    Our 50" LCD does not even get warm. Has an Internet connection and don't even need a computer for video (Amazon, Netflix, etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • SolInvictusSolInvictus Solar Expert Posts: 138
    Re: Thinking about a starter system, but no south facing roof
    glocklt4 wrote: »
    From other reading I've done on here, I would need micro-inverters or multiple strings in order to do panels facing different directions, right? Unless all of them get the same sunlight, then the panel with the least light will bring down the power of the entire array?
    Yes, the simplest is one series string on the west side and an identical one on the east side. You connect the two strings in parallel and run a single cable to your garage.
    glocklt4 wrote: »
    They have Renogy 100W panels for a good price ($160) and they have great reviews.

    Also are Tracer brand charging controllers good? They have a 20A MPPT for $130
    A 20 A MPPT charge controller for a 24 V battery array is marginal for your application. For a 500 W to 700 W PV array charging a 24 V battery array, you probably need a 30 A charge controller. If you plan to get a MPPT charge controller, then you should get the less expensive, higher voltage PV panels, like the Trina Solar TSM-240PA05 at $.99 / (rated watt). Even the high quality Kyocera's for grid-tie are less than a $1.70 / (rated watt).

    20A 2210RN 2215RN Tracer MPPT Solar Controller
    20A 2210RN 2215RN Tracer MPPT Solar Controller Specification:
    Model No Tracer-2210RN / Tracer-2215RN
    Nominal System Voltage 12VDC | 24VDC Auto work
    Rated Battery Current 20A
    Maximum Battery Voltage 32V
    Max. Solar Input Voltage Tracer-2210RN 100VDC, Tracer-2215RN 150VDC
    Max. PV input power 12V/ 260W 24V /520W
    Self-consumption* <10mA(24V)
    Charge Circuit Voltage Drop ≤0.26V
    Discharge Circuit Voltage Drop ≤0.15V
    Communication TTL232 / 8pin RJ45
    Environmental parameters Parameter
    Working temperature -35℃ to +55℃
    Storage temperature -35℃to +80℃
    Humidity 10%-90% NC
    The Tracer 2210RN limits you to 520 W of PV and 100 Voc. The Renogy 100 W PV panel has Voc = 22.5 V which exceeds the 100 V rating of the Tracer charger controller when 5 are connected in series and is too close at 90 V with 4 in series because the open circuit voltage will be higher during cold weather.
  • techntrektechntrek Solar Expert Posts: 1,372 ✭✭✭
    Re: Thinking about a starter system, but no south facing roof
    glocklt4 wrote: »
    Interesting info about the windows, and good point. My parents had their house windows redone a few years ago and I actually don't think I've discussed what kind of energy savings they have received from that. ...

    I haven't given much thought to solar water heating. I'll do some more reading into that to see if I'd like to pursue that some day. Thanks for the tip.

    Thank you for reminding me about the timer on our water heater. It has been broken for years now and I just have not taken the time to fix it. It got stuck on and never turned off the water heater. The previous owners of the house installed it. It's about time to get that fixed :).

    About 5 years ago when we needed new siding, we had the entire exterior ripped off, and the 2 x 4 studs were extended out to 2 x 6 (ripping 2 x 4s in half then scabbing them on). That allowed another layer of fiberglass before putting everything back. Our windows are unsealed double-pane, really single pane with a removable inner pane. Putting that money into insulating the 80% of the total area of the walls vs. the 20% area that the windows cover was well worth it. We mostly heat with wood and we went from 5+ cords of wood each winter to 4. There was a similar drop in our AC needs but I would have to look up the numbers to give you an exact amount. We ended up sealing the exterior up so well in the process we had to later add a whole-house fresh air system.

    Since you live where it freezes you'll need either an antifreeze-based hot water system or a drain-back system. The later automatically drains the outside loop when the circulating pump turns off at night. No need for antifreeze.
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
  • glocklt4glocklt4 Solar Expert Posts: 29
    Re: Thinking about a starter system, but no south facing roof
    BB. wrote: »
    Flooded cell batteries are expensive to ship--So, many times, a local battery supplier (even your Walmart, Costco, etc.) can be the best bank for your buck (make sure batteries are new mfg--And have not been sitting around for months uncharged).

    What kind of pricing should I expect for 6V ~200AH batteries? I found some VMAX 225AH AGM 6V on amazon for $265 shipped, no tax ($1.17/AH). It would only take 2 of these to get 12V and 450AH of capacity. Walmart has a Schumacher 200AH 6V (doesn't say it's AGM though) for $232 after tax ($1.16/AH). Academy has 12V Exide Stowaway 115Ah for $119 ($1.035/AH) and 105Ah for $108 ($1.029/AH). Overall the best value would be 420AH total with four Exide 105AH for $433 after tax. I am not sure if the VMAX are a better brand though. Open to thoughts on brand of batteries.
    BB. wrote: »
    Remember that everything revolves around conservation. A small MorningStar 300 watt inverter uses 0.6 watt on standby and 6 watts while running. You throw a 2,000-6,000 Watt TSW AC inverter out there, and you may burn 20-60+ watts just when the inverter is "ON". An Energy Star full size fridge may use ~42 watts average 24 hours per day (365 kWH per year).

    Great point here. I will certainly look into the power consumption of the inverter.
    BB. wrote: »
    Are you into computer/remote monitoring? Need to run a 240 VAC well pump? Need to parallel several inverters together for more power (even three phase power)? Like to charge from AC mains directly (internal battery charger)?

    Yes, I'm a big nerd when it comes to tying things in to monitor on a computer, however if the cost is 3-5x's that to get devices that can monitor, I can live without. I do not have a well pump. We're in DFW so we have city water. If the power to the water tower goes out, I have 200 gallons of RODI waste water that we store if there ever is a real emergency for a long period of time (and a lifestraw to drink out of it since it's not 100% contaminate free). If it comes to this, we have serious problems :).
    BB. wrote: »
    A natural gas genset would not be a bad idea... For my home, I use a Honda eu2000i (1,600 watts) as my loads are pretty small (on average). And you can get ones converted to propane/natural gas. Only uses ~1-2 gallons of gasoline per day for my backup power.

    For rare outages, a genset is not a bad deal. Don't go bigger than you need (you can easily get 8-10kW gensets), but the bigger genset can use 1 gallon per hour or more--So having a fuel supply like natural gas or a large tank of diesel/propane is needed for these large gensets.

    1-2 gallons a day is not bad. natural gas would certainly be ideal. Better for environment and unlimited supply (again as long as service is on - and if it's not, we have big problems again).

    BB. wrote: »
    Actually, for home sized system, AC vs DC current really does not matter (AC is easier to step up/step down with a simple transformer--DC needs electronics to do the same thing--But these days, MPPT--Maximum Power Point Tracking--Controllers that can efficiently down converter from high voltage/low current arrays to low voltage/high current for the battery bank.

    An insulated building can work fine. digging down a few feet in the earth can work well to moderate temperature swings too.

    Put Batteries+Charge Controllers+AC inverters in the same location/area. Install solar array remotely and/or AC power remote to home. Usually remote panels are a bit better idea (battery bank+balance of system close to home for service/monitoring is better).

    Running a "higher voltage array" (Vmp~100 VDC or more for some controllers) allows you to use much smaller gauge wiring from array to charge controller and no voltage drop/regulation issues (MPPT charge controller will accept a wide rate of voltage/current from solar array).

    In general, a 400 watt or smaller array can usually use a PWM controller (less expensive, but array cabling needs to be short). And 800 Watt or larger array generally is better supported with the more expensive MPPT type charge controller.

    Ideally batteries, charger controller and inverter would go in my garage, so I'm going to plan the system around that. Adding an insulated outdoor storage would be a good amount of work at my place and it would have to go outside of our fenced in area so it would be more open to theft/vandalism.

    I'm going to see if I can get on the roof on New Year's day when it should be 60+ deg here and measure the area that faces south to see what I've got to work with there. The west facing area would certainly be able to hold 4-6 200-300watt panels if I wanted to, and I'm guessing the south is only 4 max. The 250-300watt panels I see are mostly 24V, so it seems that this would be adequate for the DC wire run to the garage (which would be around 80ft estimated) since you said a higher voltage array would be best. Correct?

    This website has a good calculator for figuring voltage drop, and only 2.1-3.4% seems reasonable for 80ft 8/10awg copper (respectively) on 150VDC 32A (if I had four 300W panels running 37Vmp & 8Imp per panel). If I only had half these panels (two 300W) then it would be 4.3-6.8% loss. As you said, the higher the voltage, the less drop, so running higher voltage makes sense to me. http://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=3.277&voltage=100&phase=dc&noofconductor=1&distance=60&distanceunit=feet&amperes=20&x=55&y=14

    BTW, these Renogy 300W panels that are 6.5x3.25' in size seem like a good value at only 92 cents per watt ($276 each): https://www.renogy-store.com/300-Watt-Solar-Panel-p/rng-300p.htm This comes to ~14.2watt/sqft.
    BB. wrote: »
    Our 50" LCD does not even get warm. Has an Internet connection and don't even need a computer for video (Amazon, Netflix, etc.).

    That's pretty nice - even my 32" LCD gets kinda warm. It's pretty old now though. Not LED LCD.
  • solar_davesolar_dave Solar Expert Posts: 2,343 ✭✭✭✭
    Re: Thinking about a starter system, but no south facing roof
    glocklt4 wrote: »
    What kind of pricing should I expect for 6V ~200AH batteries? I found some VMAX 225AH AGM 6V on amazon for $265 shipped, no tax ($1.17/AH). It would only take 2 of these to get 12V and 450AH of capacity.

    a pair of those would be 225 AH @ 12 V. you would need 4 of them to get 450 AH @ 12V.
  • glocklt4glocklt4 Solar Expert Posts: 29
    Re: Thinking about a starter system, but no south facing roof
    Yes, the simplest is one series string on the west side and an identical one on the east side. You connect the two strings in parallel and run a single cable to your garage.

    Ahhh, I didn't realize that series is the only setup that has a problem with one panel under performing. Good to know that two panels in parallel do not effect each other. Thanks.
    A 20 A MPPT charge controller for a 24 V battery array is marginal for your application. For a 500 W to 700 W PV array charging a 24 V battery array, you probably need a 30 A charge controller. If you plan to get a MPPT charge controller, then you should get the less expensive, higher voltage PV panels, like the Trina Solar TSM-240PA05 at $.99 / (rated watt). Even the high quality Kyocera's for grid-tie are less than a $1.70 / (rated watt).

    I do plan on getting an MPPT as long as the cost isn't too much. Seems logical to make the system as efficient as possible. I'll figure out breakeven in difference between PWM and MPPT of course.

    $.99/watt (rated) is good, but is there any problem with the Renogy that I have listed previously at $.92/watt? 25 performance year warranty, 10 year materials.

    20A 2210RN 2215RN Tracer MPPT Solar Controller

    The Tracer 2210RN limits you to 520 W of PV and 100 Voc. The Renogy 100 W PV panel has Voc = 22.5 V which exceeds the 100 V rating of the Tracer charger controller when 5 are connected in series and is too close at 90 V with 4 in series because the open circuit voltage will be higher during cold weather.

    Good point on exceeding the rates with the controller. I guess I was asking more about the brand rather than that specific one for my application. Still trying to figure out sizing of everything.
  • glocklt4glocklt4 Solar Expert Posts: 29
    Re: Thinking about a starter system, but no south facing roof
    solar_dave wrote: »
    a pair of those would be 225 AH @ 12 V. you would need 4 of them to get 450 AH @ 12V.

    You're right. Forgot that 6V+6V = 12V and AH don't increase. So in this case the 12V 105AH batteries are a much better deal.
  • glocklt4glocklt4 Solar Expert Posts: 29
    Re: Thinking about a starter system, but no south facing roof
    techntrek wrote: »
    About 5 years ago when we needed new siding, we had the entire exterior ripped off, and the 2 x 4 studs were extended out to 2 x 6 (ripping 2 x 4s in half then scabbing them on). That allowed another layer of fiberglass before putting everything back. Our windows are unsealed double-pane, really single pane with a removable inner pane. Putting that money into insulating the 80% of the total area of the walls vs. the 20% area that the windows cover was well worth it. We mostly heat with wood and we went from 5+ cords of wood each winter to 4. There was a similar drop in our AC needs but I would have to look up the numbers to give you an exact amount. We ended up sealing the exterior up so well in the process we had to later add a whole-house fresh air system.

    Since you live where it freezes you'll need either an antifreeze-based hot water system or a drain-back system. The later automatically drains the outside loop when the circulating pump turns off at night. No need for antifreeze.

    I cannot even imagine ripping off the exterior siding and adding an additional 2" of studs! We are all brick housing down here, so that's impossible (realistically). Glad that worked out well for you though!

    Thanks for the comment about the hot water system since we have cold temps here. Good to know.
  • westbranchwestbranch Solar Expert Posts: 5,142 ✭✭✭✭
    Re: Thinking about a starter system, but no south facing roof

    re warranty: there has been such an upheaval in the PV industry, a lot of the best companies have gone out of existence, that placing much value on a warranty is probably an over expectation. just saying...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • techntrektechntrek Solar Expert Posts: 1,372 ✭✭✭
    Re: Thinking about a starter system, but no south facing roof
    glocklt4 wrote: »
    1-2 gallons a day is not bad. natural gas would certainly be ideal. Better for environment and unlimited supply (again as long as service is on - and if it's not, we have big problems again).

    There are many examples of less-than-apocalypse emergencies taking down the NG system. For your usual outage, no problem. But, for one example, look at the San Francisco earthquake where many NG lines ruptured. A smallish earthquake in the New Madrid fault would cut major lines.
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
  • techntrektechntrek Solar Expert Posts: 1,372 ✭✭✭
    Re: Thinking about a starter system, but no south facing roof
    glocklt4 wrote: »
    I cannot even imagine ripping off the exterior siding and adding an additional 2" of studs! We are all brick housing down here, so that's impossible (realistically). Glad that worked out well for you though!

    Thanks for the comment about the hot water system since we have cold temps here. Good to know.

    I wasn't saying you should follow the same route, only demonstrating that applying insulation somewhere other than in additional glass paid off.
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
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