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ICT

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Apr 9, 2020
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I need help and plenty of it. Most not related to this forum. I am adding solar to a camper and bought three used 315 watt panels. Panels are rated at 37.2 volts each and 8.48 amps. Now when I bought them I checked voltage and all three read about 46 volts. Now I think I know why as I live in the frozen north and it was around 35 degrees when checked. My research showed that to be correct based on temp? It also gets at least 55 degrees colder here. Yes 20 below and sometimes worse. Based on these temps I am going with lead acid batteries. So now for the questions. Series or parallel? Why? What size mppt and brand? Why? Inventor charger? Why? Here is what I will be running. A few lights, USB ports and a water pump all 12 volts. The main reason for the solar is to run a 5,000 btu window A.C, a microwave in short bursts and a dorm fridge/freezer. I am also not opposed to 24 volts if that is the answer. I also have a 2000 watt and a 1000 watt gas portable generators when needed. Okay folks open to any and all ideas.
 

Supervstech

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5KBTUH window unit depending on the weather can run your batteries down fast.
900Wx5hours average is 4500Wh generation on a good day of sun. Figure you will get 1/2 that average days... so 2300Wh of production. Size the battery bank at double your daily load, x days of autonomy... but the load needs to be supplemented with generator use, or spend days recharging without USING energy until full...
series is good if you have a quality MPPT controller that can handle the volts, and you don’t get shade... if you get shade, parallel is a wiser choice, but that will limit you to 24V battery bank with those panels.
 

ICT

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Thanks for your response. Hard to know how much the A.C. would actually run each day but will cycle off and on. Like many will chase 70 degrees. Any recommendations on MPPT?
 

Supervstech

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Thanks for your response. Hard to know how much the A.C. would actually run each day but will cycle off and on. Like many will chase 70 degrees. Any recommendations on MPPT?
Victron is great.
 

ICT

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Thanks again. What size for series or parallel? Might be a big part of how I wire.
 
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