randp
Solar Newcomer
Posts: 5
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Post by randp on Feb 10, 2019 18:35:52 GMT
The 3 panels will be 60 to 80 feet from the batteries. 12 volt system. Would it be better to run the 3 panels in Series, (36 to 50 volts approx) to the 40 amp MPPT controller (80 feet away), which would then step it down to 12 volt at the battery?
Or do you hook three panels parallel, and run the 12-17 volt to the 40 Amp MPPT controller? Just thinking about line loss, voltage drop, etc when running longer distances.
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Post by tattoo on Feb 10, 2019 18:46:39 GMT
You will have loss either way that far away.... It will come out about the same either way...
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Post by tattoo on Feb 10, 2019 18:49:27 GMT
By the way what kind of panels do you have??? They should have a max of around 18v ea parallel or series on a good day not just 12v...
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Post by bupkis on Feb 10, 2019 19:01:46 GMT
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Post by Admin on Feb 11, 2019 1:19:18 GMT
The 3 panels will be 60 to 80 feet from the batteries. 12 volt system. Would it be better to run the 3 panels in Series, (36 to 50 volts approx) to the 40 amp MPPT controller (80 feet away), which would then step it down to 12 volt at the battery? Or do you hook three panels parallel, and run the 12-17 volt to the 40 Amp MPPT controller? Just thinking about line loss, voltage drop, etc when running longer distances. Would agree that series is probably the way to go if shading is not an issue. In addition, increasing your gauge, if you have the means, should help. Our adaptor kits, the wires that go from solar panels to charge controller are limited to 10Awg unfortunately. -Renogy Team |
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randp
Solar Newcomer
Posts: 5
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Post by randp on Feb 13, 2019 14:21:52 GMT
I am using three RNG-100D panels. Mounted on my Green House (NO Shade), about 40 feet away from my home. All power in the greenhouse is 12 volt (water pump, lights, etc) and when i built my house, all lighting inside (except Ceiling fans) is 12 volt (mostly standard Can Lights with 12 volt LED floods instead of 120 volt, and lots of low voltage under cabinet type LED lighting)
so I need 12 volt in the green house, and 12 volt in my house. I can Run 8 ga wire, (I have a 60 foot roll) but it would be tough. I would prefer to run 10 ga.
I plan on a Rover 40 A MPPT controller in the greenhouse to change batteries there, and another 40 amp MPPT controller in the house, to charge the batteries in the house. Obviously I may add more panels some day... (doesn't everyone?)
Looking at the voltage calculator:
80 foot wire run
240 watts at 12 volt (20 amp) with 10 ga wire= 27% loss, or 8.7 volts output... (WOW!)
Same thing with 8 ga wire , 17% loss, or 9.9 volts...
But step it to 240 watts at 48 volts (5 amp), 10 ga wire, and it is only 2% loss (47 volts out)
same 240 watts at 48 volts with 8 ga wire, it drops to 1% loss, or a 1/2 volt drop.
I am not sure what the exact system voltage will be but it sounds like running the higher voltage series connections will be the better way to go.
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Post by tattoo on Feb 13, 2019 15:33:20 GMT
I am not sure what the exact system voltage will be but it sounds like running the higher voltage series connections will be the better way to go. It's always a better way to go....
Is there a reason your not wanting to run your system on AC? Just a question? |
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randp
Solar Newcomer
Posts: 5
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Post by randp on Feb 18, 2019 13:19:51 GMT
I am out in the country, and prone to power failures. Sometimes for a few minutes to a hour, sometimes days. When the power goes out, all my lights inside still work. (I have woke up at night, and did not realize the power was out til I noticed the clock was off). So that sort of makes the power failures "not a big deal". If the power stays off, I start up the generator. It is a rope start 6500 watt Honda, but since all my lights still work, I am not working in the dark. Right now I have a float charger keeping the batteries in the house charged. I am installing solar just because... and the Green house is a good spot for the panels.
The green house has a solar powered water pump, and 1000 gallon water storage. When the sun shines, the pump runs, and circulates the water through 200 feet of black pipe up next to the peak, warming the water to keep the green house warmer at night. A second 12 volt pump pumps runs off a battery, to water the plants. (two solar panels, one for the heat,connected directly to the circulation pump, and one to charge the battery.) At the time, it was fun, and easier that trenching in a 120 volt line.
Since the Greenhouse was built, i have "expanded" my solar (and will be trenching in electric wires). When I built the green house, I had room for 4 solar panels on the panel"frame" on the roof (16 feet long, 2 feet high). I am just now getting to installing more panels.
BTW, I am building a 3000 watt, 240 volt grid tie system too. I plan to mount the panels on a 20 foot trailer. I can then move them if I need too. Plan to connect it much like I would connect a Generator to my house.
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