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  • Advice on off grid solar project

    Hey there new to the fora here but have been doing research and it keeps bringing me back here so I figured I'd ask for some advice. I have 4 100watt panels and I'd like to set them up about 150ft away from my offgrid cabin. So I was thinking of wiring them up in series to get a high voltage and more efficient/cheaper wire run up to the cabin into an mppt cc. This would then charge my batteries I have two 80ah gla deep cycles from autozone I only use one right now because I have a 1500watt inverter for 12v. However I bought all this and didn't plan so it's going to change my question is should I make it 24v or 48v and then buy a new inverter. My whole goal is to run a mini fridge 80watt at 120v. So what do you think would be the best bet thanks for any advice.

  • #2
    Originally posted by Mr sunspot View Post
    Hey there new to the fora here but have been doing research and it keeps bringing me back here so I figured I'd ask for some advice. I have 4 100watt panels and I'd like to set them up about 150ft away from my offgrid cabin. So I was thinking of wiring them up in series to get a high voltage and more efficient/cheaper wire run up to the cabin into an mppt cc. This would then charge my batteries I have two 80ah gla deep cycles from autozone I only use one right now because I have a 1500watt inverter for 12v. However I bought all this and didn't plan so it's going to change my question is should I make it 24v or 48v and then buy a new inverter. My whole goal is to run a mini fridge 80watt at 120v. So what do you think would be the best bet thanks for any advice.
    Higher the better, but either will work if you find a deal on the right inverter, do not buy the first one you see, running a a/c fridge of any kind is not easy unless it is just a weekend here and there in the summer with full sun somewhere, then you still need a good inverter usually pure sine if you want the fridge to last. Most standard mini fridge use near 600wh per day, your panels should be up to that if it is summer only and not much shading (full sun, most of day), lots of losses throughout the system to account for and high startup current on the fridge, one of the more difficult loads a person can attempt to run off of a basic solar setup. 24v is going to be cheaper to come up with a battery bank. Your location, sun hours, and full time, or part time on running the fridge will factor in, 48v probably not quite worth it at this stage for you?
    Last edited by LETitROLL; 06-27-2017, 11:42 PM.

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    • #3
      Originally posted by Mr sunspot View Post
      I have 4 100watt panels and I'd like to set them up about 150ft away from my off grid cabin. My whole goal is to run a mini fridge 80watt at 120v. So what do you think would be the best bet thanks for any advice.
      You had better tap the breaks because 400 watt is not near enough to run that fridge. Anyway the best way to do this is located the panels, batteries and Inverter all at the sam elocation so you can transport the higher 120 VAC over the distance. You also need to get out of that 12 volt box you are stuck in.

      MSEE, PE

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      • #4
        First off thanks for replying guys..Really don't feel stuck just need to figure it all out and buy accordingly. I may have messed up on my fridge purchase do you know of any more efficient ways to have off grid refrigeration? Ill sell it if I need to barly used because I can't run it haha. I also need to figure out a good charge controller any advice on that was thinking victron 75/15 or 100/15 or mayb the midnight the kid seems like I could expand with more panels that way. Also I looked for bigger panels for cheap on ebay but couldn't find any do you know where to get them reasonably..100 watt panels were85$ so I will add more if I need to. I guess if it were you and you needed refrigeration what would your setup be I you only had off grid solar, I also have a 1700watt Wind turbine at 12volts so is there a way to use that to my advantage or did I buy that wrong too now that I want to go higher voltage. The hope here is too run the fridge all day(when the sun is shining) off surplus solar (batteries are full) and only need battery for night and cloudy days.. Hopefully the wind turbine will work or mayb I can exchange it for a higher voltage one. Thanks again I'm just starting down this road of making my own power already very conservative on power but with enough panels and wind( we love on open fields channeling up a hill) and some advice I'm hoping to pull this off. Thanks again this is just for summer when we have sun winter is not a problem as long as it's cold out haha

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        • #5
          Most "mini-fridges" use as much power as a full size, standard fridge. Over 1Kwh per day. Most energy star fridges are around 1Kwh or less per day. Mini-fridge is not an energy saver.
          400w of panels may run a fridge in the summer with long days, but will fall short in the winter,

          and planning on 48V system is the better/more robust way to go.
          Powerfab top of pole PV mount (2) | 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

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          • #6
            Originally posted by Mr sunspot View Post
            First off thanks for replying guys..Really don't feel stuck just need to figure it all out and buy accordingly. I may have messed up on my fridge purchase do you know of any more efficient ways to have off grid refrigeration? Ill sell it if I need to barly used because I can't run it haha. I also need to figure out a good charge controller any advice on that was thinking victron 75/15 or 100/15 or mayb the midnight the kid seems like I could expand with more panels that way. Also I looked for bigger panels for cheap on ebay but couldn't find any do you know where to get them reasonably..100 watt panels were85$ so I will add more if I need to. I guess if it were you and you needed refrigeration what would your setup be I you only had off grid solar, I also have a 1700watt Wind turbine at 12volts so is there a way to use that to my advantage or did I buy that wrong too now that I want to go higher voltage. The hope here is too run the fridge all day(when the sun is shining) off surplus solar (batteries are full) and only need battery for night and cloudy days.. Hopefully the wind turbine will work or mayb I can exchange it for a higher voltage one. Thanks again I'm just starting down this road of making my own power already very conservative on power but with enough panels and wind( we love on open fields channeling up a hill) and some advice I'm hoping to pull this off. Thanks again this is just for summer when we have sun winter is not a problem as long as it's cold out haha
            I have a Victron 75/15 and love it for the money. Often you can pick up an panel or 2 from leftovers of bigger jobs, i have found a few good deals in my area just by keeping an eye on classified ads, leftover new 200-300 watt panels for about .50 to.65 per watt. Best options for off -grid refrigeration, if it is a full time system then best to go to a DC compressor type refrigerator, the savings in less system losses, more efficient, and not needing a large high quality inverter allow you to get away with somewhat smaller solar array, and somewhat smaller battery bank, which end up being huge over time, they are a little pricey, but so is a large high quality pure sine inverter, which you pretty much need with any AC unit, plus the more expensive solar setup. (battery banks are a BIG loser, so the smaller you can keep that the better, no matter what else) If you do go AC the only real way to get by with a "not very large" battery bank is to get one of the small ac chest freezers and make things colder (and/or extra ice) during the day when sunny, and then power down, or raise thermostat and coast during the night, if your in an area that might get 3 days in a row or more of mostly cloudy, then you would need a generator to save your batteries.(and keep your beer cold)
            Last edited by LETitROLL; 06-28-2017, 10:42 PM.

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