Hoping you Solar Guru's can help me

All,

The variances in designing a system are mind-boggling! I will just lay out what I want my system to do and hopefully you can point me in the right direction.

As we all know, the economic picture for America is bleak and only getting worse. It is my belief that we are headed for an economic meltdown in the near future and that ultimately the grid will go down. With this in mind, it is my wish to create and solar/generator/battery bank system that will supply power for the long haul.

I live in Andover, Minnesota and we consume on average 2100Kw/month. Obviously in a SHTF situation I do not need that much power; just enough for rudimentary living. I would like to be able to power a normal sized freezer and refrigerator 24/7 but beyond that just intermittent use of some lighting, appliances, and light tools. Heat would be supplied by kerosene heaters so I shouldn't need power for gas furnace. We have an electric water heater but I am assuming the power consumption on that would be rather high. Same for Air Conditioning.

For sunless days/winter/longterm adverse conditons, I would use a diesel generator to recharge the batteries.

I see alot of people using 48V battery bank configurations these days. Is that what I should go with? If so, I have been reading I should not go more than three strings parallel to up the amperage. Is this true? My thoughts were a 24V setup utilizing 6V 224 Ahr batteries in a 4 x 3 (12 batteries total) grid bank. 24V 672 Ahr. Is this to little or not enough or is there a better solution for my intentions? The batteries would be located in my basement next to the AC panel so would probably have to use sealed AGC batteries.

I realize I don't have exact numbers but if you could just generalize and provide an example that would be helpful. I know my freezer says 120V 5A. Not sure on the refrigerator.

How many solar panels would be needed to properly charge that battery bank? What is the minimum size diesel generator needed to properly charge that bank? 5k? 7k?

I will be installing this system myself to save money and I am not really interested in State credits and all that or supplying the grid with extra energy. I don't want to spend a ton of money but I am not doing cheap either. It must be durable and able to survive 10 or more years.

Your help is greatly appreciated,

Bill (another one)

Comments

  • mike95490mike95490 Solar Expert Posts: 8,369 ✭✭✭✭✭
    Re: Hoping you Solar Guru's can help me

    You will first need to get a Kill-a-Watt meter, and let it measure your fridge and freezer, each for a week, to come up with a consumption figure. For long term, consider getting Energy Star fridge & freezer, they are pertty good for efficency, and use standard parts. To get higher capacity, you can use 6V batteries, or even 2V batteries, in series, to get 48V @ 800A or even larger.
    But you can't randomly chose a battery size, you need to look over your electric bill KWh per month, and consider a solar preheat for your water heater.
    mike
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • BB.BB. Super Moderators, Administrators Posts: 29,482 admin
    Re: Hoping you Solar Guru's can help me

    Welcome to the forum.
    As we all know, the economic picture for America is bleak and only getting worse. It is my belief that we are headed for an economic meltdown in the near future and that ultimately the grid will go down. With this in mind, it is my wish to create and solar/generator/battery bank system that will supply power for the long haul.
    From, an engineering point of view--I don't believe we will see a collapse of the grid (i.e., no grid for months/years). What we may see are outages (sunny afternoons with lots of A/C power usage and storm damage that takes days-weeks to repair instead of hours--but that already happens in some parts of the country today).
    I live in Andover, Minnesota and we consume on average 2100Kw/month. Obviously in a SHTF situation I do not need that much power; just enough for rudimentary living. I would like to be able to power a normal sized freezer and refrigerator 24/7 but beyond that just intermittent use of some lighting, appliances, and light tools. Heat would be supplied by kerosene heaters so I shouldn't need power for gas furnace. We have an electric water heater but I am assuming the power consumption on that would be rather high. Same for Air Conditioning.
    Long term high power usage is a drain on funds... So, my two cents would be to recommend an agressive conservation (assuming you have not done that already). Several advantages--reduces current costs of energy usage (more money available for other projects/savings for job losses, etc.). Also can make the home more livable during power outages (high/low temperatures outside temperature extremes do not make the home unlivable without A/C / Heating and also allows you to use less precious energy to maintain home comfort). I am a big believer in double pane vinyl windows and lots of ceiling/wall/weather stripping.

    Energy star rated major appliances will make off-grid easier to do too... CFL's, gas/propane water heater (or tankless water heater, or small 6 gallon RV water heater for backup), efficient A/C or Heat Pump for cooling/heating, etc...

    You can also prepare for conversion to high efficiency living--Get a refrigerator range thermostat to convert a chest freezer to a chest refrigerator--perhaps 1/3-1/4 of the energy use of a standard energy star/off grid refrigerator.

    Chest freezer as a chest refrigerator
    For sunless days/winter/long-term adverse conditions, I would use a diesel generator to recharge the batteries.
    I am a big believer in optimizing loads to battery to genset (and to solar panels)... If you can minimize the loads--then the other stuff gets smaller/cheaper, and your fuel use/requirements\ goes down tremendously too.
    I see alot of people using 48V battery bank configurations these days. Is that what I should go with? If so, I have been reading I should not go more than three strings parallel to up the amperage. Is this true? My thoughts were a 24V setup utilizing 6V 224 Ahr batteries in a 4 x 3 (12 batteries total) grid bank. 24V 672 Ahr. Is this to little or not enough or is there a better solution for my intentions? The batteries would be located in my basement next to the AC panel so would probably have to use sealed AGC batteries.
    I am the guy guilty of pushing minimizing large numbers of parallel strings... I personally see the one string of large cell'ed batteries as a more cost effective solution than a 4 or more parallel strings of small cell'ed batteries.

    Easier to take care of one string with 12 cells to monitor/water than to do the same thing with 4x12=48 cells.

    Try costing out two different battery banks of the same capacity with 1 string vs 4 strings (including cabling, fuses/breakers per string, etc.)...

    You may come to a different decision--and that is fine. Some people like two strings--if once cell fails, they have a backup string until that cell/battery can be replaced.
    I realize I don't have exact numbers but if you could just generalize and provide an example that would be helpful. I know my freezer says 120V 5A. Not sure on the refrigerator.
    You can look up your freezer online and it may have the energy tag listed (like 365 kWHrs per year is 1 kWH per day).

    Then, how many hours of full sun per day do you have... Say 9 months of the year you have a minimum (average) of 4 hours of sun. Assuming this is a standard solar power system, flooded cell battery, and inverter--We start with a derating factor of 0.52--yes, your system is only 52% efficient. So, working backwards:
    • 1,000 Watt*Hours * 1/0.52 * 1/4 hours of sun = 481 Watts minimum of solar panels to power an efficient Energy Star Freezer 9 months of the year.
    In reality, you need to purchase a Kill-a-Watt Meter or equivalent. Measure your true load over 24 hours (summer will be higher, cold winter temperatures will be less). Nameplate ratings on many appliances will lead you to way overestimating power usage:
    • 120 VAC * 5 amps * 24 hours = 14,400 Watt*Hours = 14.4 kWH per day
    Unless this is a 30 year old freezer, very large, or has problems (water logged insulation, low refrigerant charge, etc.)--that is about 2x the daily electrical load of my entire home.
    How many solar panels would be needed to properly charge that battery bank? What is the minimum size diesel generator needed to properly charge that bank? 5k? 7k?
    We need numbers... Ideally, a diesel generator should be operated with 50-60% minimum load (for long life and fuel efficiency). And you have a 5%-13% recommended charging rate for a battery bank...

    Again, you need to work backwards from your known loads/requirements back to the storage and energy systems for best cost efficiency (i.e., I am a cheap guy).
    I will be installing this system myself to save money and I am not really interested in State credits and all that or supplying the grid with extra energy. I don't want to spend a ton of money but I am not doing cheap either. It must be durable and able to survive 10 or more years.
    Solar/off grid solar/Hybrid solar will not save you money. Only conservation will save you money.

    Sizing your system to your loads/requirements will save money and frustration too.

    -Bill 'not the first or the last" B.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • surefirewizardsurefirewizard Registered Users Posts: 5
    Re: Hoping you Solar Guru's can help me

    Thanks to both of you for the quick responses.

    From, an engineering point of view--I don't believe we will see a collapse of the grid (i.e., no grid for months/years). What we may see are outages (sunny afternoons with lots of A/C power usage and storm damage that takes days-weeks to repair instead of hours--but that already happens in some parts of the country today).

    In the economic collapse I envision, the dollar (due to hyperinflation) becomes worthless paper in a short amount of time. Not sure about you, but I am not going to go to work if I am making worthless US dollars. It won't be long from that point that the electrical infrastructure (among others) collapses as there will be no one to a) operate it b) maintain it and c) repair it. Everyone will be at home or bugging out and taking care of they and theirs. At any rate, thats a whole other discussion 8)
    Energy star rated major appliances will make off-grid easier to do too... CFL's, gas/propane water heater (or tankless water heater, or small 6 gallon RV water heater for backup), efficient A/C or Heat Pump for cooling/heating, etc...

    Yes, you have helped me decide that I will purchase a smaller, higher energy efficient freezer model for my garage and just take the other one out of the picture if things go bad.

    Thanks for the battery info also. I will get a kill-o-watt and start doing some measuring and come back with hard results. No sense trying to guess what my load will be.
    Unless this is a 30 year old freezer, very large, or has problems (water logged insulation, low refrigerant charge, etc.)--that is about 2x the daily electrical load of my entire home.

    Brand new freezer but it is a large full sized freezer. I will have to do the kill-o-watt on it. After looking at my electric bill our house consumes about 67 kwh per DAY on average. So basically we consume 10 TIMES what your home does. Thats sad.

    Again, thanks for your insight. Very helpful. I will post again when I get the hard data from the kill-o-watt.

    Bill
  • BB.BB. Super Moderators, Administrators Posts: 29,482 admin
    Re: Hoping you Solar Guru's can help me

    You can also look for whole-house type energy measuring systems... The T.E.D. has been around for awhile--as well as others (I don't have any of them--do your pre-purchase evaluation/ask questions--by the way, if you go with Grid Tied solar, not all whole-house systems can handle the bi-directional energy flow).

    Trying to avoid the political side of the question (we do have an Energy / more Political discussion section if you want to post articles for discussions and such.

    My example of what may happen with a grid is what we see in many countries today... Afternoon blackouts and night-time power...

    A nice battery bank with connected inverter/charger is not a bad solution in that situation. Obviously, you can add solar panels and generators to the mix... And even look at a Hybrid Inverter (grid tied/off grid capable).

    Grid Tied Hybrid is probably your best choice (if Net Metered power is supported by your utility). It is the most cost efficient because the batteries sit in "float" (best for long term battery bank life) and you can use the "grid" as your "AC Battery Bank". If/when the grid fails, your system trucks along nicely with the off-grid inverter operation, battery bank, and your recharging sources (solar, wind, generator, etc.).

    Another issue is that you need clean water and food (locally grown, preserved/pickled/salted/sugared/etc. for storage) for long term survival. Electrical power is not (usually) the limiting factor in that situation. Alternative Fuel (food, hot water, heating) is another issue to plan for...

    I am not sure that I would have no-grid but still have diesel fuel/kerosene for a long term SHTF as you describe it.

    Planning for water pumping (solar powered pump, avoid batteries), purification, heating (solar thermal), and cooking (again, solar oven) that avoid the whole PV Electrical/battery issue is something that should be looked at too...

    In the end--my personal aim point has been 100 kWhrs per month--that is the old number that people who wanted to be "off gird" planned for when solar panels where over $10 per Watt (instead of the less than $3 per Watt we see today).

    Direct water pumping from solar panels--no batteries to wear/fail. Solar thermal panels ("free hot water"). Even the seemly low-tech Solar water pumping can have some surprisingly high-tech components (such as the 80-180 VDC/AC/solar/battery/AC generator powered water pump technology--very cool stuff--but not 1920's simple).

    You can certainly do more--but the complexity/battery bank/generator issues just become a whole another level of problems.

    -Bill

    By the way, I live in a very temperate climate (SF Bay Area)--so my heating/cooling needs are not the same as yours. Also, I have natural gas for a very low-cost source of heat.

    I am not trying to hold myself as an example of "holier than thou green guru"... More of just an example of life style choices... I put in energy efficient appliances, don't use an electric dish-washer, keep the thermostat low, line dry cloths, and insulated the heck out of a 70 year old home.... Was not cheap. May not even be cost effective... Everyone makes personal choices for them and their families.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • surefirewizardsurefirewizard Registered Users Posts: 5
    Re: Hoping you Solar Guru's can help me
    Grid Tied Hybrid is probably your best choice (if Net Metered power is supported by your utility). It is the most cost efficient because the batteries sit in "float" (best for long term battery bank life) and you can use the "grid" as your "AC Battery Bank". If/when the grid fails, your system trucks along nicely with the off-grid inverter operation, battery bank, and your recharging sources (solar, wind, generator, etc.).

    If I develop a grid tied system isn't that inherently a rather large system based on my current usage in order to offset as much as possible? If the grid goes down and stays down won't I be left with a system that is too large to use effectively/efficiently? If the grid stays down I will only be using the freezer (summer storage of food) and various other items intermittently.

    Damn near everything in my house is electric - which is why we are consuming almost 2000kwh per month. Water heater, double oven, two freezers, one refrigerator, dryer etc.

    I am very interested in a "hot water" solution though and will have to research what you mentioned about solar applications for that. Separating out those items you mention (solar oven, water heating, etc) to run on their own solar power makes sense.

    Again, thank you much for your help and guidance.

    Bill
  • BB.BB. Super Moderators, Administrators Posts: 29,482 admin
    Re: Hoping you Solar Guru's can help me
    If I develop a grid tied system isn't that inherently a rather large system based on my current usage in order to offset as much as possible? If the grid goes down and stays down won't I be left with a system that is too large to use effectively/efficiently? If the grid stays down I will only be using the freezer (summer storage of food) and various other items intermittently.
    Xantrex makes a nice system--the XW Hybrid Inverter. Both Grid Tied and Off Grid capable (i.e., Hybrid). The nice thing is you can generate electric power to offset power during "normal times" -- and it at least provides some return on your "investment". And you connect only those loads that need power in an emergency (freezer, fridge, lights, well pump, possibly a heat pump mini-split Sanyo AC/Heat system for a couple rooms) to the "protected" sub panel.

    Note that the new Mini-Split Sanyo A/C system (and heat pump for winter heating--at least down to near 32F)--is roughly 2x more efficient than a typical window AC unit and can run on low power (3000 BTU) around 300 watts--very off-grid solar friendly. Also, in heat pump mode, it is ~2x as efficient vs an electric heater (again probably above 32F).

    Yes, the "rest of the home" would be without AC power--but trying to power a 50-85 gallon electric hot water heater/et. al. from solar panels + battery bank is just not even worth trying.

    If you can look at heat pumps for High Efficiency (perhaps even ground sourced) AC/Heating and even heat pump hot water--it may make sense for some solar.

    From my point of view--a 3kW solar array and related equipment is usually the low end of a Grid Tied / Hybrid system. It will not generate a huge amount of power for you--but may be a worthy investment for off grid--if/when that need happens.

    A 3kW GT array will generate for Minneapolis will generate (using PV Watts, all default settings):
    "Station Identification"
    "City:","Minneapolis"
    "State:","Minnesota"
    "Lat (deg N):", 44.88
    "Long (deg W):", 93.22
    "Elev (m): ", 255
    "PV System Specifications"
    "DC Rating:"," 3.0 kW"
    "DC to AC Derate Factor:"," 0.770"
    "AC Rating:"," 2.3 kW"
    "Array Type: Fixed Tilt"
    "Array Tilt:"," 44.9"
    "Array Azimuth:","180.0"

    "Energy Specifications"
    "Cost of Electricity:"," 7.9 cents/kWh"

    "Results"
    "Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh)", "Energy Value ($)"
    1, 3.85, 301, 23.78
    2, 4.72, 322, 25.44
    3, 4.97, 363, 28.68
    4, 4.91, 327, 25.83
    5, 5.74, 380, 30.02
    6, 5.91, 369, 29.15
    7, 5.89, 379, 29.94
    8, 5.64, 364, 28.76
    9, 5.21, 336, 26.54
    10, 4.28, 296, 23.38
    11, 2.95, 203, 16.04
    12, 2.85, 217, 17.14
    "Year", 4.74, 3857, 304.70
    200 to 380 kWhrs per month for Grid tied system.

    Converter that to Off Grid (more losses)--assume 0.52 derating factor:
    "Station Identification"
    "City:","Minneapolis"
    "State:","Minnesota"
    "Lat (deg N):", 44.88
    "Long (deg W):", 93.22
    "Elev (m): ", 255
    "PV System Specifications"
    "DC Rating:"," 3.0 kW"
    "DC to AC Derate Factor:"," 0.520"
    "AC Rating:"," 1.6 kW"
    "Array Type: Fixed Tilt"
    "Array Tilt:"," 44.9"
    "Array Azimuth:","180.0"

    "Energy Specifications"
    "Cost of Electricity:"," 7.9 cents/kWh"

    "Results"
    "Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh)", "Energy Value ($)"
    1, 3.85, 200, 15.80
    2, 4.72, 215, 16.98
    3, 4.97, 241, 19.04
    4, 4.91, 216, 17.06
    5, 5.74, 251, 19.83
    6, 5.91, 243, 19.20
    7, 5.89, 250, 19.75
    8, 5.64, 240, 18.96
    9, 5.21, 222, 17.54
    10, 4.28, 195, 15.41
    11, 2.95, 133, 10.51
    12, 2.85, 143, 11.30
    "Year", 4.74, 2548, 201.29
    As you can see--an off grid system is much less efficient (batteries, and extra conversion)--and you can see, in winter, you are down to 133-145 kWhrs per month or ~4.5 kWhrs a day--not a lot of power.

    So--you get an idea of what 3kW of solar panels can do for you and your family.

    Note that a Grid Tied / Hybrid system is eligible for some government rebates (like the 30% federal tax credit). Pure off grid systems are not (as far as I know--I am not a tax guy either).
    Damn near everything in my house is electric - which is why we are consuming almost 2000kwh per month. Water heater, double oven, two freezers, one refrigerator, dryer etc.
    Unless you are into spending a whole bunch of money for your solar system--(several $100,000???).... ???
    I am very interested in a "hot water" solution though and will have to research what you mentioned about solar applications for that. Separating out those items you mention (solar oven, water heating, etc) to run on their own solar power makes sense.
    Hot water is a possibility--but for your climate, it may require a closed loop system (antifreeze) to prevent damage. Solar thermal can be a good return on investment. There was a "solar shed" project to provide hot water for radiant floor heat too.

    This is one post from an entire thread that discusses the many ideas/options for solar and conservation... Here is one post:
    BB. wrote: »
    I have trimmed these posts from another thread and intend to put everything together in a Stick FAQ/Thread... Please feel free to add suggestions and update information as you see fit.
    ...
    If you want a do-it-yourself kit... This one appears to be hard to beat:

    www.solarroofs.com

    Solar Guppy has many years experience with a system from them and has been pretty happy. It does require proper maintenance to keep running well and to prevent problems (like freeze damage).

    There have been a few threads here that link back to several extensive home projects--right down to installation photos, and documentation of mistakes and corrections...

    Link 1
    Link 2
    Link 3
    www.arttec.net/Solar/BarnHeat.html (also sells battery based Differential temperature pump controller).

    Follow the off-forum links. The several projects/websites highlighted are very educational.

    And this one is a bit more low tech home made heating system. Also very interesting and informative.

    Between the two above links, they probably give the best detailed explanations of how to do a major home heating/domestic hot water project that I have seen.

    The second one is, by itself, probably not practical for a city home system--but both give great ideas of the scope of such projects.

    By the way, the "solar oven" was more a nod to the insulated box lined with aluminum foil and a glass cover for use in remote areas where fire wood/fuel is scarce and expensive. Not a practical solution for use in a western style home. (sorry).

    In the end, you are probably paying around $0.10-$0.20 per kWhr for electricity. And, realistically, full off-grid solar/generator back power will cost you around $1-$2+ per kWhr (dividing costs over 20 years of power generation).

    To power your existing home from Solar/Generator--you are looking at the equivalent of $2-$4,000 per month power bills (and in California, those bills would be in the $1,000-$1,500 a month range on our grid power now).

    Conservation and alternative fuels are going to be your friend here--both now and in the future.

    Lots of hand waving until we understand your required loads and possible configuration needed for your home (grid tied, hybrid, off grid, what you want/need to power, etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • peterakopeterako Solar Expert Posts: 144 ✭✭
    Re: Hoping you Solar Guru's can help me

    As a standby generator look around for slow speed diesel generators.
    Whit simple care you have a good generator and you can use the water to help heat the house.:D

    If you look around you will find that most of the slow speed diesels can run easy on bio diesel or vegteble oil. that will help in case of a problem like you expect.( it will be difficult to find fuel or spare parts then so prepare and stock.)

    Greetings from Greece8)
  • surefirewizardsurefirewizard Registered Users Posts: 5
    Re: Hoping you Solar Guru's can help me

    Bill,
    Xantrex makes a nice system--the XW Hybrid Inverter. Both Grid Tied and Off Grid capable (i.e., Hybrid). The nice thing is you can generate electric power to offset power during "normal times" -- and it at least provides some return on your "investment". And you connect only those loads that need power in an emergency (freezer, fridge, lights, well pump, possibly a heat pump mini-split Sanyo AC/Heat system for a couple rooms) to the "protected" sub panel.

    Now this is an interesting option but in Minnesota a completely off-grid solar setup would qualifiy for a rebate as well from what I can tell. See link below and see if you agree.

    http://www.dsireusa.org/incentives/incentive.cfm?Incentive_Code=MN09F&State=federal&currentpageid=1&ee=1&re=1

    Are there additonal costs associated with a completely off-grid install (excluding maintainance)? If the install cost is the same then it makes sense to go hybrid as I could offset some eletrical usage until such time the grid goes down.

    Bill
  • mikeomikeo Solar Expert Posts: 386 ✭✭✭
    Re: Hoping you Solar Guru's can help me
    Are there additonal costs associated with a completely off-grid install (excluding maintainance)? If the install cost is the same then it makes sense to go hybrid as I could offset some eletrical usage until such time the grid goes down.
    The cost of off grid vs hybrid should be around the same. The main advantage of a hybrid install is that you can offset 20-50% of your power usage with a smaller solar installation, trade excess generation off to the grid and get it back when you need it under net metering. When power goes out, just trim your load to the Hybrid capacity that you have available.
  • BB.BB. Super Moderators, Administrators Posts: 29,482 admin
    Re: Hoping you Solar Guru's can help me
    Now this is an interesting option but in Minnesota a completely off-grid solar setup would qualifiy for a rebate as well from what I can tell. See link below and see if you agree.

    www.dsireusa.org
    Looks like you are correct. Since it appears that you need a professional installer with 2 system installs in the last 12 months to qualify--they should be able to answer that question for you. Also--there is a fixed amount in the budget--in California, there was a reservation system (money approval before you installed system). In Florida, I understand you had to install the system and hope there would be money allocated the next year.
    Are there additional costs associated with a completely off-grid install (excluding maintenance)? If the install cost is the same then it makes sense to go hybrid as I could offset some electrical usage until such time the grid goes down.
    Hardware wise, if you use a Xantrex XW Hybrid system, an Off-Grid and Grid Tied version of the system will have the same hardware costs.

    With Grid Tied--you may have building permit/inspection costs. And the utility Net Metering programs can be a bureaucrat hell of rules and billing hassles. Although, once you are connected, you are pretty much left alone (although, you may have high monthly connection/billing charges, 2nd meter, etc.).

    If you have grid power, and want to build a nice emergency power system--the Hybrid Grid Tied System is pretty nice. All of the solar power you generate is fed into your homes A/C wiring--and any excess power spins your meter backwards (you may get money or credit for next month/year billing--depends on utility and if they allow GT connected solar systems.).

    Another plus is that your battery bank sits in "float" charge 99% of the time--so you only cycle the battery bank when you actually lose AC power.

    With a pure off-grid system, you can only store ~3 days of useful power and if you don't use the power, you lose it--and if you don't have enough, you have to turn on your generator (or use grid power if available). Plus, you are cycling the battery bank--Which is only 80% efficient and does take life from the bank through cycling loads/charging.

    Sort of depends on what you need and how much you want to pay (utility power with backup genset is usually the cheapest, Grid Tied solar next, Hybrid GT solar is more expensive, and Off-Grid solar the most expensive).

    For most people, Utilty power / Grid Tied is around $0.10-$0.30 per kWhr. Hybrid may be around $0.45-$0.75 per kWhr, and off grid can cost around $1-$2 per kWhr (including battery replacement and fuel costs--not including generator cost).

    Unless you have utility issues (high rates, really poor/non-exitent Net Metering plan, etc.)--A Grid Tied or Hybrid Grid Tied system have the best costs over time.

    A properly designed Hybrid GT/OG system will operate exactly the same as a "pure" OG system (in fact, the XW Hybrid inverter is installed in many pure off grid systems with generator backup--very functional, reliable, and good costs).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • jeffkrusejeffkruse Solar Expert Posts: 205 ✭✭✭
    Re: Hoping you Solar Guru's can help me

    Don’t forget that you need a charge controller $$ and possibly an E panel $$ when you go off grid. Don’t forget the cost of insurance $ each year when your grid tied. +’s and –‘s
  • surefirewizardsurefirewizard Registered Users Posts: 5
    Re: Hoping you Solar Guru's can help me

    I am starting to feel that just buying some land further up north with a small cabin that I can outfit with a much smaller solar system sounds a lot better for a few reasons:

    Lower cost
    Easier to maintain (ground based vs fixed roof)
    Further north and more isolated

    As it turns out my current house is orientated east-west instead of north-south like I thought so strings on the roof would not likely work out very well if at all, at least not in a very cost effective measure.

    Is it fairly straight forward to maintain and keep healthy a system that is off-grid?

    Bill

    EDIT: By lower cost, I mean that we wanted some camping land to begin with so I am not including the cost of the land and any structures.
  • BB.BB. Super Moderators, Administrators Posts: 29,482 admin
    Re: Hoping you Solar Guru's can help me

    An off-grid system has extra costs--primarly the battery bank--that Grid Tied systems don't...

    If you monitor your battery bank, purchase a good brand, and keep it reasonably charged and serviced--they will give you a decade +/- of service...

    The electronics (inverters, chargers, etc.) seem to "start to fail" around 10 years of life and you will pretty much be replacing them after 15+ years. Repairing old electronics (in this age of rapid improvements) is, many times, just not possible... Lighting can be a big cost factor (and safety) if you live out in the wild (either you are near big trees which attract the lightning, or your place is the highest point near a lake an your elevated panels/wind turbine are attractors).

    Good quality solar panels will last 25-40 years without much issues (other than rocks, hail, etc.).

    More or less--if you keep the system small--then the repair/maintenance/oh-heck stuff is not too expensive either.

    Look at Tony/Icarus' sig:
    300 watts Siemens/BP panels,plus a Sun 90,, making ~300. ~30 amps into Rogue MPT-3024 controller,into 450 ah of Trojan T-105, powering a Morningstar ts300 inverter, and monitored with a Tri-Metric meter.a collection of antique generators, plus 2 Honda eu-1000i's (also a BS2512 IX controller) and some assorted other stuff!

    400 watts of solar panels in Canada--computer, internet, etc.... Uses an old gasoline engine powered washer. A couple "newer" small Honda 1,000 watt generators plus lots of old gensets for shop power when needed.

    They also use a propane powered fridge too (although--someday an electric fridge plus more solar panels+battery capacity is a desire of his).

    It does not take much to "have enough power" for a nice day to day life--assuming that life is not very energy intensive.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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