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Design Stage for Off Grid Generator and Battery Shed

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  • MacGyver
    replied
    Originally posted by homer View Post
    Couple of things to consider. 48 volts system. If they improve electric car batteries, and bring the cost down, they could be your next set. Are you sure you need your generator in autostart? I don't think your batteries will freeze, with the solar.
    You don’t need to freeze a battery to kill them.

    People killed batteries the weapon of choice is chronic deficit charging, or not doing battery maintenance. ALL batteries including AGM needs to be recharge to 100% SOC within a day or two before they start to loose Ah’s. The first signs of a problem is filling the generator fuel tank daily not weekly follow by replacing the battery bank $$$$.


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  • Iboondock
    replied
    Originally posted by homer View Post
    Couple of things to consider. 48 volts system. If they improve electric car batteries, and bring the cost down, they could be your next set. Are you sure you need your generator in autostart? I don't think your batteries will freeze, with the solar.
    In my case, I have a steady 50 watt draw for remote monitoring/control/security. It's not unusual in December that 2200 watts of solar won't cover that load during daylight, much less provide any charging. Without that load, solar would probably cover the draw of just the charge controller.

    Leave a comment:


  • ChugiakTinkerer
    replied
    Originally posted by hunter1951 View Post

    from my understanding lithium batteries do not work well in the cold -5 and they stop functioning
    Yep, that's my understanding as well.

    I think I'll stick with the proposed AGM batteries. They have the best performance at low temperatures and are more freeze-resistant. But I'll still be putting the batteries and electronics in an insulated enclosure. With the internal power draw of the equipment and the heat generated when charging the batteries it will be equivalent to having a 60W light bulb on. So it shouldn't be an issue to keep the batteries above freezing. I can add another heat source too, such as the aforementioned light bulb or perhaps a battery blanket, heat mat, etc.

    I am more concerned about the enclosure overheating in the warmer months. So that will be something to plan for. Maybe something as trivial as vents that get plugged with insulation in the fall and removed in the spring. Or a thermostatically controlled vent fan. My goal is to keep the batteries in the recommended range of 32 to 104 F.

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  • hunter1951
    replied
    Originally posted by ChugiakTinkerer View Post
    MacGyver, The system they specced for me is based on my guesstimate of what future energy use will be. The system is 24V, with an inverter capable of 4000 watts. I'll have to look up what the range of daily energy use was, but as I recall it was 4 to 5 kWhr per day. That's pretty substantial, but I envision having remote internet with a continuous weather station and remote monitoring, plus many of the comforts of home. I hadn't considered lithium batteries, I'll have to do some reading up on those. Thanks for the inout, and let me know if I've missed something obvious. CT
    from my understanding lithium batteries do not work well in the cold -5 and they stop functioning

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  • lyuluck
    replied
    1.The real wattage of an off-grid solar system is the total wattage of solar panels X hours of sunshine X 0.6(wire lost) X Sin Light angle, due to the effect of snow or dust it will even lower. Thus you should calculate the real power in conservative calculations.
    2.As the battery is charged and discharged each time, its actual electricity capacitance will decrease. It is important to check the battery condition regularly.
    3.If the battery is over-discharged, the battery may freeze at extremely cold temperatures. In this situation, neither solar system nor diesel generators can generate electricity when connected to frozen batteries, but in your plan, there is a room with a constant temperature, that can prevent the liquid from freezing.
    4.Bluesolar MPPT is a good controller for the solar system, and you can download an APP which can show the voltage, wattage, and more details,that MTTP will prevent the battery from freezing and inform you when and where the problem happens.
    5.It is best to use monocrystalline solar panels in high latitude areas.

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  • MacGyver
    replied
    With out heat .....It’s a hole new ball game when it comes to batteries.



    At the time I suggested using lithium battery the OP was going to be keeping the battery warm. No heat ....no LiFePO4 storage batteries.


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  • homer
    replied
    Couple of things to consider. 48 volts system. If they improve electric car batteries, and bring the cost down, they could be your next set. Are you sure you need your generator in autostart? I don't think your batteries will freeze, with the solar.

    Leave a comment:


  • Iboondock
    replied
    Originally posted by MacGyver View Post


    Hi iboondock: May I ask how long you had the batteries and what batteries are your using?
    You need more panels is it because of your location, weather or snow on the panels?
    I have Rolls S-530 batteries and I've had them for just about 8 years. More panels would help in the shoulder seasons, especially the fall when we can get the long stretches of rain. And it would mainly be to reduce generator time. December will always be generator month, but I think I could get it down to 45 days.

    I'm not going add them now, but if I was building today I could get almost twice the array for the same cost I paid for what I have. I am able to put my panels vertical in the winter so snow isn't an issue.



    I was going to ask where you were located because I didn't think that possible in AK., but I clicked on your "about" page and see that you are in Anchorage. Very impressive! Should I assume you heat with wood?
    Yes we heat with wood. Maybe I should clarify, this isn't our full time residence, this is a cabin in the Matsu.

    Leave a comment:


  • 4merguide
    replied
    Originally posted by Iboondock View Post
    We're 100% solar from mid January thru mid October. November and December are generator months..
    I was going to ask where you were located because I didn't think that possible in AK., but I clicked on your "about" page and see that you are in Anchorage. Very impressive! Should I assume you heat with wood?

    Leave a comment:


  • MacGyver
    replied
    Originally posted by Iboondock View Post

    I have 19.2kw in battery (48 v), 2200 watts of solar,
    If I was doing this today I would double the solar, and leave everything else the same.

    Hi iboondock: May I ask how long you had the batteries and what batteries are your using?
    You need more panels is it because of your location, weather or snow on the panels?

    Leave a comment:


  • ChugiakTinkerer
    replied
    Thanks homer and lboondock, appreciate the details.

    Leave a comment:


  • Iboondock
    replied
    Originally posted by ChugiakTinkerer View Post

    I'd appreciate more details on your solar and generator installations, if you don't mind.
    I have 19.2kw in battery (48 v), 2200 watts of solar, Schneider MPPT 60/150 CC, Magnum inverter, 7 kw Generac generator. I have the Magnum magweb for monitoring and the AGS manages the generator. With the controller that came on that model of generator it was a 5 minute, $5 modification to make it a 2-wire start that draws zero power when it's off. I understand it is much harder or impossible to do this with the new series controllers. If I was doing this today I would double the solar, and leave everything else the same.

    Leave a comment:


  • homer
    replied
    My details: My place is done in the high desert. It gets plenty cold -25* ,but plenty of sun. 2500 watts of panels, outback charge control, outback 3648 inverter. Onan 4kw propane. 8 x 16 insulated power room, in a barn. 8 6volt golf cart batteries. 48 volts system. 10 years so far.

    Leave a comment:


  • ChugiakTinkerer
    replied
    Originally posted by Iboondock View Post
    I opted for a propane generator. It's located outside under a roof to keep the snow off. The coldest I've had to start it was -38, it ran fine for about an hour and then started to starve for fuel, a little heat to the tank fixed that . I added a tank heater that is powered only when the generator is running and haven't had fuel issues again down to -30 so far. I have three 100# bottle manifolded together. I have engine and battery heaters installed on the gen that I use to preheat when temps are below -20.

    Over 7 years we've averaged 65 hrs of annual runtime, and fuel consumption averages about 1 gal/hr. We're 100% solar from mid January thru mid October. November and December are generator months.

    If you're not going to keep the batteries warm, you need to derate the bank accordingly.

    My opinion- If your property is a good solar site, add as much solar as practical, panels are cheap and going to get cheaper. At a minimum max out whatever charge controller you're considering for the system.
    I'd appreciate more details on your solar and generator installations, if you don't mind.

    Leave a comment:


  • Iboondock
    replied

    I opted for a propane generator. It's located outside under a roof to keep the snow off. The coldest I've had to start it was -38, it ran fine for about an hour and then started to starve for fuel, a little heat to the tank fixed that . I added a tank heater that is powered only when the generator is running and haven't had fuel issues again down to -30 so far. I have three 100# bottle manifolded together. I have engine and battery heaters installed on the gen that I use to preheat when temps are below -20.

    Over 7 years we've averaged 65 hrs of annual runtime, and fuel consumption averages about 1 gal/hr. We're 100% solar from mid January thru mid October. November and December are generator months.

    If you're not going to keep the batteries warm, you need to derate the bank accordingly.

    My opinion- If your property is a good solar site, add as much solar as practical, panels are cheap and going to get cheaper. At a minimum max out whatever charge controller you're considering for the system.

    Leave a comment:

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