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Mike G.
Mike G., Master Electrician
Category: Electrical
Satisfied Customers: 7244
Experience:  Proven Professional 48 years Experience
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Solar Electrical Wiring Question: I'm designing a solar set

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Solar Electrical Wiring Question: I'm designing a solar set up for our RV. 3 160W 9.4A, 12V nominal, panels on roof. Panels in parallel to a combiner box on roof. Then wire from combiner box to solar charge controller. Then from solar charge controller to house batteries (2 x Group 24 Deep Cycle). I want to select wire size to minimize voltage loss - less than 1% would be ideal. Wire from Panels to combiner box is #10. Furthest panel to combiner box approx 12-15 feet. My guess from combiner box to solar charge controller would be 12-14 feet. Then approx 4 feet from charge controller to battery.
If I keep the #10 wire from the panels to the combiner box - what guage wire should I use from Combiner box to Charge Controller and to battery? I think 2 AWG... but then the solar charge controller I want to use (Bogart Engineering SC2030) says the biggest wire it can accept is a 6AWG. I would really like to wire bigger than 6AWG to and from the charge controller... but I don't know how to connect a 2 AWG wire appropriately to something that will only hold 6AWG. Some people say just remove a few strands from big wire, but that doesn't sound like a good idea.
Also, I would like to get some type of on/off switch between the Combiner box and solar charge controller.
Could I run 2AWG from combiner box to the on-off switch that would be right next to the charge controller. Then run 6 AWG from the on-off to the charge controller?

Hi, I'm Mike and I'll be assisting you. Please stand by while I review your question.

Customer: replied 4 months ago.
Thank you Mike :)

To reduce the wire size splice a #6 copper to the #2 at the termination. The voltage drop will not be affected. It is based on the length of the circuit and not for a splice at the end.

Customer: replied 4 months ago.
Silly question - what do I need to do a splice? Is this where a butt connector comes in? LOL! I'm still learning quite a bit. I won't be the one doing the actual install but I want to understand it myself too.
Customer: replied 4 months ago.
Can you tell me the voltage drop for my proposed system?

A split bolt connector with tape would be suggested. Your voltage drop will be under 1 volt.

Customer: replied 4 months ago.
Can you recommend a youtube video or a picture showing a split bolt connector with tape? I'm looking at the pictures online and I don't quite see how that connection would work. Forgive me, definitely new to this. And again, I won't be doing the installing but want to understand
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