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 > Setting up my solar system

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GravelRider

Pennsylvania

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Posted: 08/13/20 09:05am Link  |  Quote  |  Print  |  Notify Moderator

Okay, so now that I'm thinking about it, if I just use a solar parallel connector rated for 30 amps, I could put a waterproof inline fuse on each of the positive leads, then only run one set of wires down, and if I use about ten feet of 10 AWG wire from the parallel connection (48 V, 20 amp), I'll get a 0.87% drop in voltage, which sounds okay to me.

In other words:

Solar panels --> 10 AWG 48 V, 10 amp (maybe 5 feet?) --> parallel connection --> 10 AWG 48 V, 20 amp (10 feet) --> controller --> 2 AWG 14 V, 50ish amps, likely less due to real world numbers (5-7 feet)

This calculator from Renogy recommends 10 AWG if 12 feet or less in the 20 amp run of wire. I think this is very doable and would make my life a lot easier.

https://www.renogy.com/calculators#tab_solar-cable

* This post was edited 08/13/20 09:17am by GravelRider *

GravelRider

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Posted: 08/13/20 09:06am Link  |  Quote  |  Print  |  Notify Moderator

By the way, thank you everyone for all of your help. I'm definitely learning as I go.

CA Traveler

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Posted: 08/13/20 09:51am Link  |  Quote  |  Print  |  Notify Moderator

I used this on the CC output. https://www.waytekwire.com/item/46691/80A-Bussmann-Circuit-Breaker/

Be aware that generally panels should be connected/disconnected with the CC on. So you would need to pull/insert fuses.


2009 Holiday Rambler 42' Scepter with ISL 400 Cummins
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Bob


CA Traveler

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Posted: 08/13/20 09:58am Link  |  Quote  |  Print  |  Notify Moderator

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GravelRider

Pennsylvania

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Posted: 08/13/20 10:07am Link  |  Quote  |  Print  |  Notify Moderator

CA Traveler wrote:

I used this on the CC output. https://www.waytekwire.com/item/46691/80A-Bussmann-Circuit-Breaker/

Be aware that generally panels should be connected/disconnected with the CC on. So you would need to pull/insert fuses.


I'll be using a circuit breaker (same one you linked, just different amperage) between the parallel connection and the CC, so I'll be able to switch that off without pulling the fuses.

GravelRider

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Posted: 08/14/20 06:58am Link  |  Quote  |  Print  |  Notify Moderator

I picked up my panels yesterday. Wow are they big! I'm glad I measured first. Otherwise I'd be nervous about them fitting. I am going to have a hell of a time getting these up on the roof and maneuvered around...

[image]

(They completely cover the door behind it)

I ordered an Epever 60 amp MPPT controller. The reason I went with this one was that it had good reviews on Amazon and, more importantly, output wire size is 2 AWG. I was amazed at how hard it is to find output maximum wire size with the vast majority of these controllers. I had to mostly search reviews and Q&A where I could usually only find vague answers from someone who said they "used 8 AWG, and maybe it could fit 6, but I'm not sure," etc. I really appreciated that the Epever does accept 2 AWG and that they clearly state it on their information sheet. As it turns out, I have about 50' of 2 gauge from a prior project, so that'll definitely be what goes from the controller to the battery bank.

Everything else needed for the install is now ordered, and scheduled to arrive today and tomorrow. I've got the weekend off, and it would be a great time to install... Except that it's supposed to rain all weekend!

JKJavelin

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Posted: 08/14/20 07:04am Link  |  Quote  |  Print  |  Notify Moderator

I like your periodic table.
Oh, nice panels!


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570 watts of Solar

2017- 21 Nights
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CA Traveler

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Posted: 08/14/20 08:00am Link  |  Quote  |  Print  |  Notify Moderator

You'll have a nice setup.

GravelRider

Pennsylvania

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Posted: 08/14/20 10:29am Link  |  Quote  |  Print  |  Notify Moderator

CA Traveler wrote:

For 2 parallel panels no breaker required. For 3 it's a good idea. Usually fuses are used in the combiner box on the roof, not likely they will ever blow. Use 15A as 10A is to close to the panel or whatever the panel specs say. There are effects such as cloud edge that can cause max current.


I was doing some more reading and came across this article: https://www.windynation.com/jzv/inf/how-properly-fuse-solar-pv-system#:~:text=Commercially%20made%20solar%20panels%20over,30%20amps%20of%20current%20flow.&text=In%20the%20case%20of%20panels,20%20amp%20fuses%20are%20required.

"Commercially made solar panels over 50 watts have 10 gauge wires capable of handling up to 30 amps of current flow. If you connect these panels in series, there will be no increase in current flow so fusing is not required for this string. This is not the case when you have panels connected in parallel, as when connected in parallel the system current is additive. For instance if you have 4 panels each capable of up to 15 amps, then a short in one panel can draw all 60 amps towards that short-circuited panel. This will cause the wires leading to that panel to far exceed 30 amps causing that wire-pair to potentially catch fire. In the case of panels in parallel, a 30-amp fuse is required for each panel. If your panels are smaller than 50 watts, and use only 12 gauge wires, and 20 amp fuses are required."

So really I probably don't need fuses at all, since if all the current flowed through just one wire, I'd still be fine. But, after reading this, I think I'll just go with 20 amp fuses.

GravelRider

Pennsylvania

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Posted: 08/14/20 10:30am Link  |  Quote  |  Print  |  Notify Moderator

JKJavelin wrote:

I like your periodic table.
Oh, nice panels!


LOL. Thanks. My garage brewery is off to the left of the picture.

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