new kid on the block

leonphelpsleonphelps Registered Users Posts: 5
Hello,

Will be getting into the game soon. Basic residence. Has gas and electric. Thinking of getting most off the grid, but want the ability to do it as I go. Place is 3k ft2. Large garage that is not heated, but would probably put some electric heaters in it when I get into my system savings.

Thinking of starting with 8 200w panels. They will charge 8 12v batteries wired to get 48v. I am planning on using dry cell batteries. Have them in four boats, a quad, a pwc. I swear by them. Want the 48v converted to 220v 5000watt or so electric during peak usage. Largest electric usage item is my dryer. Want the ability to use my compressors, plasma cutter or welder off of solar. Most of the circuits would break off of one leg of the panel, but the stuff listed would be the 220 stuff I need the inverter for.

Place has two breaker boxes. Plan is to take the one box off the grid initally. Thinking of starting with the one and letting it roll for a while and monitoring the voltage and seeing where I am at with the different times of the day/month with my reserve. If all goes well, then I would start stealing circuits to a new panel until I feel comfortable with my setup.

Place has gas heat and hot water. I was thinking of putting an electric water heater upstream of the gas heater eventually and using that heater to get water to 100 degrees then letting the gas do the rest. Was also planning on running several new circuits in the house for electric radiant heaters. Nothing too large, just stuff set on low to take some work off of the heater during the winter. Once they are in there, I would play with the numbers to keep batteries in peak range. There is central air also, one window unit is used continuosly on the top floor. It is a small 5k unit.

Hot summer month and winter cold months my energy runs about $450. When weather is nice it is only $150 or so.

Does this sound like a decent plan for my place?

as for costs...figuring
8 panels $1800
charge controller $400
Batteries....$1600
48vdc-220vac inverter...$1000
wires...$500
battery box $50

Panels can go on a flat roof I have about 15' above current breakers. Then need to go down wall then in house to controller, then to batteries in box, then to inverter, then into my off grid system. I would need to get a ballast system for the panels on the roof also.

Any suggestions/recommendations would be appreciated.

Comments

  • BB.BB. Super Moderators, Administrators Posts: 29,350 admin
    Re: new kid on the block

    Welcome to the Forum Leon,

    In general, I really push for conservation first... Insulation, double pane windows, more insulation, using energy star appliances, CFL and LED lighting, and just plain turning stuff off. Many people that have never done "extreme conservation", can pretty easily save about 50% of the power bill through basic improvements to their home/appliances.

    In my humble opinion, your money goes farther with conservation vs just installing a big-old off grid power system. Grid Tied solar (solar array + Grid Tied Inverter) is the one variable in the saving money game--It is possible, with a good billing plan from your local utility, to generate power at the same cost as Utility Power, or even for less if you live in a state like California where people with high electric bills an pay upwards of $0.30 to $0.40 per kWH or more for summer afternoon power.

    If you need heat, you can go with solar thermal (water, hot air, etc.)--That can even work in places with some snow on the ground.

    Otherwise, if you need heat and A/C, air sourced heat pumps are being used off grid this days--And even heat pump based water heaters (about 2-3 times more efficient than pure resistive water heating--and Cold+Dry air is the "waste" from water heating--For hot/humid climates cold+dry air is very helpful). However--We still are talking about relatively small systems.

    When you look at $450 power bills (electric?)--What is your actual kWH per month usage (by season). In a lot of areas, that is something like a 2,200 to 4,400 kWH per month load.

    A very energy efficient home using Off Grid solar power may be in the range of 100 kWH per month. A very large off grid one may be in the range of 1,000 kWH per month... That is a, relatively large and expensive solar power system to install and maintain.

    And, I am very interested in hearing more about your Dry Cell based battery bank. To this point, Lead Acid has been the major option and a few people are trying Nickle+Iron and various Lithium chemistries. They all have their pluses and minuses--But there has not been a real game changer/change to plain old Lead Acid cells.

    Any links/brands you wish to discuss would be interesting.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: new kid on the block

    WOW! First impressions, after reading your post several times, is that you are expecting to reap huge results from a relatively small system.
    If I'm reading it right, you've got to either make really drastic cuts in your expectations, OR prepare to install a drastically larger solar system from start to finish.
    Please do a lot more reading and studying before you make any purchases so you hopefully can avoid grief.
    Why are you looking at solar - - is it because you live far from grid lines, or is it because you believe solar electric is a money saver over grid power?
  • leonphelpsleonphelps Registered Users Posts: 5
    Re: new kid on the block

    BB,

    Thanks for the conservation advice. Went this route for the past 5 or so years. Managed to cut about $125 per month off the bill. Have about 40 CFL's inside and 15 CFL lights outside. Also have insulated cellular pleated shades, argon filled windows, blown foam insulation in all areas possible.

    I am in PA, they are not too friendly for generators. The fees and inspections necessary if I wanted to sell the energy back on the fly would cost me a couple thousand a year for this luxury. The meter is a hundred and fifty a month and then the inspections would be twice a year to make sure it was working properly. I have an electric meter that is tied back to the provider that alerts them if it spins backwards so grid tie matched sine wave is out of the question the first time I make more than I am using. red flag will be thrown.

    Optima makes blue cell batteries that are close to a couple hundred bucks. 1000CCA 12v deep cell. I have one in a truck right now that is over 15 years old. Was in a cabin cruiser I own for 10+ years, then in a pontoon for a couple then in my truck over 3 years. still works great.

    Wayne,

    If I put in this system and could leave my AC on and heat on high both with an electric bill of $50 per month, I would be good with that. Saving $3500 ($300+- a month for 12 months) a year with a 5-6k investment would make sense, no? I really dont think this is expecting anything big. Did you? I have detached garages I could heat for free with the extra energy that would be a plus too.
  • SolInvictusSolInvictus Solar Expert Posts: 138
    Re: new kid on the block
    leonphelps wrote: »
    Thinking of starting with 8 200w panels. They will charge 8 12v batteries wired to get 48v. I am planning on using dry cell batteries. Want the 48v converted to 220v 5000watt or so electric during peak usage. Largest electric usage item is my dryer. Want the ability to use my compressors, plasma cutter or welder off of solar.

    Optima makes blue cell batteries that are close to a couple hundred bucks. 1000CCA 12v deep cell....
    Using electricity from PV panels to heat water and rooms is not cost effective. Using surplus power from PV panels for heating has some merit.

    Eight 200 W PV panels would give you about 8 * 200 * .75 * 6 h = 7.2 kWh on a great day and considerably less on a bad day. Is that enough for an air conditioner or heater?

    A 48 V battery array with 2 series strings would draw 5000 W / .75 / 48 V / 2 = 69 A from each battery. Is the battery you are contemplating an Optima 34M / 1000M Battery? The specification sheet states:
    Model: 34M
    These batteries are designed for engine starting applications. They are not recommended or warranted for use in deep cycle applications.

    Capacity: 50 Ah (C/20)
    Reserve Capacity:
    BCI: 110 minutes (25 amp discharge, 80°F (26.7°C), to 10.5 volts cut-off)
    50 Ah / 20 h = 2.5 A at the 20 hour rate of discharge.
    25 A for 1 hour and 50 minutes to a complete discharge.

    Eight of these batteries are unsuitable for sourcing 5,000 W.
  • BB.BB. Super Moderators, Administrators Posts: 29,350 admin
    Re: new kid on the block
    leonphelps wrote: »
    I am in PA, they are not too friendly for generators. The fees and inspections necessary if I wanted to sell the energy back on the fly would cost me a couple thousand a year for this luxury. The meter is a hundred and fifty a month and then the inspections would be twice a year to make sure it was working properly. I have an electric meter that is tied back to the provider that alerts them if it spins backwards so grid tie matched sine wave is out of the question the first time I make more than I am using. red flag will be thrown.

    A grid tied system is the only solar power system that can (so far) really save you money.

    Typical off grid power costs around $1-$2+ per kWH (initial installation costs, plus new batteries every X years, and new inverters/charge controller every 10+ years).

    There have been a few folks here that have obtained close to $0.50 per kWH--But that requires a lot of work and shopping for best prices on their side (plus a good sunny climate--usually).
    Optima makes blue cell batteries that are close to a couple hundred bucks. 1000CCA 12v deep cell. I have one in a truck right now that is over 15 years old. Was in a cabin cruiser I own for 10+ years, then in a pontoon for a couple then in my truck over 3 years. still works great.

    But what is the actually "20 hour discharge rate" Amp*Hour capacity? According to this spec... The largest Optima is only 75 AH at a C/20 discharge rate (D31M--just a quick scan of the specs).

    If you cycled a single battery by 50% per day, and paid ~$0.20 per kWH, it would give you:
    • 75 AH * 12 volts * 0.50 max discharge * 1 kWH/1,000 WH * $0.20 per kWH = $0.09 worth of electricity per battery
    If you wanted to "use" $300 worth of stored power from the battery bank per month, you would need (very roughly):
    • 12 volts * 75 AH * 0.50 * 1kWH/1,000WH = 0.450 kWH per battery (1 day cycle)
    • $300 / 30 days = $10 per day
    • $10 * 1/$0.20 per kWH = 50 kWH per day
    • 50 kWH per day / 0.450 kWH per Optima Battery = 111 Batteries to cycle $300 of electricity per month at $0.20 per kWH
    • 111 batteries * $200 per battery = $22,200 worth of batteries
    I think I got all the numbers correct.

    Obviously, this is not going to be a very cost effective system. This is probably not the right battery for this application.
    Wayne,

    If I put in this system and could leave my AC on and heat on high both with an electric bill of $50 per month, I would be good with that. Saving $3500 ($300+- a month for 12 months) a year with a 5-6k investment would make sense, no? I really don't think this is expecting anything big. Did you? I have detached garages I could heat for free with the extra energy that would be a plus too.

    I still am not sure how much you pay for for power--$0.20 per kWH will be my guess for now. If you want to do $300 worth of power per month, I will run through the math real quickly:
    • $300 per month * 1/$0.20 per kWH = 1,500 kWH per month
    • 1,500 kWH per month / 30 day sper month = 50 kWH per day = 50,000 WH per day

    Battery sizing, 48 volt battery bank, 2 days of storage and 50% maximum discharge:
    • 50,000 WH * 1/0.85 AC inverter eff * 2 days of storage * 1/0.50 max discharge * 1/48 volt bank = 4,902 AH @ 48 volts
    You will need 6x Crown Industrial Battery - 24 Volts, 1720 Amp-hours Price: $6,801.40 = $40,808.40

    If you only have 1 day of storage, then you could use just 3 of the above batteries.

    Solar Array--Sizing first based on battery bank (using larger 4,902 AH 48 volts):
    • 4,902 * 59 volts charging * 1/0.77 panel+charger derating * 0.10 rate of charge = 37,561 Watt Array Nominal
    Next is sizing for how much sun you get... Using PV Watts, fixed array, Philadelphia:
    Month    Solar Radiation (kWh/m 2/day)
    1      3.30     
    2      4.16     
    3      4.74     
    4      5.06     
    5      5.20     
    6      5.43     
    7      5.51     
    8      5.67     
    9      5.07     
    10      4.59     
    11      3.37     
    12      2.67     
    Year      4.57
    

    Toss the bottom three months, gives us a "break even month" for February at 4.16 hours of sun per day:
    • 50,000 WH per day * 1/0.52 system efficiency * 1/4.16 hours of sun = 23,114 Watt Array "break even" February
    An array of ~23,114 to 37,561 at $1.00 per Watt will cost you around $23,000 to $37,500.

    Of course, there is the mounting hardware, wiring, permits, installation labor, solar charge controllers (~6x $700 80 amp MPPT charge controllers for a 37 kWatt array). You need a couple of AC inverter+charge controller, etc...

    At this point, a lot more than $5,000-$6,000 investment so far--The above battery bank could be 1/2 that size if you only want one day of storage... and that would allow a 1/2 size solar array (almost)...

    Anyway, not trying to design the system--Just showing at a 1,500 WH per month system would cost if it was for a full off grid home.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: new kid on the block
    leonphelps wrote: »

    Wayne,
    Saving $3500 ($300+- a month for 12 months) a year with a 5-6k investment would make sense, no? I really dont think this is expecting anything big. Did you? I have detached garages I could heat for free with the extra energy that would be a plus too.

    It should work great for you, only one little thing, - - - you're a bit off on the initial cost of such a system. As you can see from BB's post (and he DOES know what he's talking about), a system that would do what you want, would cost not $5-6K, but with labour and all the little extra but necessary things, more like $100,000.00, give or take a little. Oh, and every 5 to 10 years you'd be looking at another $40,000.00 to replace warn out batteries.
    All this of course assumes you'd only be wanting a 2 day reserve for sunless periods. If you needed more than that, well, the costs go up accordingly.
    Now if I were a psychopathic salesman who's only interest was taking all the money I could convince you to hand over, I'd be glad to totally agree with your initial thoughts and sell you that $5K-$6K system you were first thinking about. Then I'd quickly vanished into thin air and move on to my next victim.
  • verdigoverdigo Solar Expert Posts: 428 ✭✭
    Re: new kid on the block

    Another field of dreams turned into a parking lot.
  • leonphelpsleonphelps Registered Users Posts: 5
    Re: new kid on the block
    verdigo wrote: »
    Another field of dreams turned into a parking lot.
    lol.

    I did not plan on any permits. I could do the install myself. I feel confident in that.

    I do have a source for other batteries used. They are the other optima line, I get what I can used. They are the red and yellow tops that I get used. I buy blues for myself and have lots of spares during the winter when they are not in boats/vehicles.

    I was only planning on rising water temp a little, not going the whole 35-120 degree rise. now that I think of it, to 100 would be unreasonable. 70-80 would be more likely.

    Same it true for the heaters. only the small oil radiator types. would not buy them up front, would save my way into them.

    considering the sunless periods that probably happen 2-3 times a year, wouldnt it just be safe to plug a battery charger in for a few hours to get you out of a jam? know it sounds counter productive, but this is all about saving money.

    thanks for all of the help.
  • Blackcherry04Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    Re: new kid on the block

    The old adage, you can lead a horse to water but you can't make them drink. Most of us have been where you are ( especially the Early Pioneers ), every system works to some degree. Take a couple of your used batteries and hook them up to a Inverter and plug in your heater / load and see how long it runs. That will give you a base line as to where you need to go. If it doesn't run, then your Inverter is to small or your battery bank and wiring is to small. If it runs for two minutes you'll only have 1,438 minutes to go to get it to run for 24 hrs. It's called trial and error, I'd expect that $20-$50,000 would get the job done.
  • BB.BB. Super Moderators, Administrators Posts: 29,350 admin
    Re: new kid on the block

    80 batteries in series/parallel is not going to cut it either... There are lots of good reasons that such a battery bank would not be stable/successful. and there are other expensiveness too (wiring/fuses or breakers per string, etc.) that really drive up the costs of such a bank construction.

    Maintenance/debugging of a massively parallel battery bank--You really do not want to do that (20 parallel strings for a 48 volt system).

    You could go with a ~192 volt DC input AC inverter (larger computer rooms will use high voltage battery banks)... But then you get into issues with finding/designing a high voltage solar charge controllers system (most mainstream solar chargers are limited to 48 volt battery banks, there is one that may be able to do 120 VDC battery bank).

    You would be on the cutting edge of "home solar power" system design--And large battery banks (in my humble opinion) are scary dangerous to work on. Such a large battery bank could be in the range of Arc Flash--A whole 'nother level of safety issues.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Ski66Ski66 Registered Users Posts: 11 ✭✭
    Re: new kid on the block

    Hello Leon, I too live in Northeast Pa. In reviewing your plans and intentions I would like to add that I do agree with BB, in energy conservation. I previously wrote an article
    on some basic inexpensive ways to reduce the energy consumsion I know you have changed your light bulbs to LED or CFL, but when I started that I really did not know how
    many bulbs I really had, even the one's in the Dryer , Refig, cable boxes, and Freezer, could add up the cost. The change over to Solar has been a 3 year process for me, and still ongoing. Please check all your options and specs, prior to saying ready set go,, This is a great forum, and I have received some of the best advise from everyone here. From what you stated your electric bill is around 450 a month, at our rate in PA that is about 2500 KWH a month @ .18 per KHW is what we pay once you include the distribution , taxes , and fee's. If that shows on your electric bill, I would advise to start with a Kill-a-watt meter , and set some inexpensive timers on the basic items such as coffee makers, cable boxes , etc ( they use about 25 watts even when there off , and there is 720 hr in a month, That right there is 18000 wh, or 18 KWH a month, now using a simple timer you could reduce the energy consumption in half, and possibly more if you have more then one cable box. 18 Kwh is only a savings of 3.24 a month, or 38.88 a year, it all adds up : )
    With you intentions on 200 watt solar panels , I would consider a 240 watt solar panel , you could use less panels , and these would be compatible with the Emphase M215 inverter should you ever want to GTI / Net metering with you local electric provider in the future. Hope this helps with you project. Good luck and welcome aboard.
    Paul
  • PNjunctionPNjunction Solar Expert Posts: 762 ✭✭✭
    Re: new kid on the block

    Quick note about anyone contemplating Optima blue-top batteries mentioned earlier for solar ... they come in two different versions - an SLI only version with the black or dark-grey case, and the dual-purpose one with a very light gray casing.

    The light-gray cased versions would be the ones to use in a deep discharge setup. My friend ordered one without knowing this, and got the wrong one for his little portable solar setup.
  • SolInvictusSolInvictus Solar Expert Posts: 138
    Re: new kid on the block
    leonphelps wrote: »
    Same it true for the heaters. only the small oil radiator types. would not buy them up front, would save my way into them.
    One way to use surplus PV power to heat a room is to use incandescent bulbs controlled by a relay that turns them on when the battery voltage gets to, say, 56 V and turns them off when it drops below, say, 54 V. This way, you do not have to worry about the heater discharging the batteries.
    leonphelps wrote: »
    considering the sunless periods that probably happen 2-3 times a year, wouldnt it just be safe to plug a battery charger in for a few hours to get you out of a jam? know it sounds counter productive, but this is all about saving money.
    Yes, using grid power to backup a PV system is functional.

    AGM batteries are an expensive option. Golf cart batteries would be cheaper for your initial experiments. You could get 260 Ah from 8 Trojan T-145 6 Volt, 260 AH Deep Cycle Batteries for $1,624 and have only one series string.
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