600W System Series / Parallel Decisions Also Fusing

[rawtoxic]

So I've been reading all afternoon and getting more and more confused as to series / parallel wiring my panels and how to fuse.

Here is what I have:
6x x 100w renogy panels (4x 100 watt panels from this kit https://www.renogy.com/400-watt-12-volt-solar-rv-kit/ - upgraded to better controller below - 1x 100w new matching panel and re-using 1x 100w renogy panel that is 3 years old from existing setup)
renogy 40a li rover mppt controller (I know it may be limiting when we rarely get a full 600w)
210 ah 12v agm battery from old system I'm upgrading from (will replace with 200-300ah lithium self heating at some point - i think - seeing if prices come down)
50 amp breaker for between controller and battery

All to be flat mounted on roof of our small Provan Tiger CX RV. Off grid RV use. Want to charge e-bike batteries and run RV systems mainly fridge, lights and heater. We camp year around in shaded areas sometimes and do travel in winter regularly - usually trying to stay in areas above 20f overnight lows and above freezing daytime (Rv only 3-season built). We live on continental divide in Colorado store RV outdoors in colder temps probably as low as -10f - usually I keep panels on maintaining battery charge....

I get all the wiring past charge controller etc but I am perplexed as to the best approach to wire up and fuse the panels in series or parallel that will best service our needs.

Main questions I have:
1) What would be the best wiring layout for the panels - originally I thought 6 in parallel would be best but after reviewing fuse posts I became aware it maybe 2s3p or 3s2p similar layout ? Some posts I read indicate I may overload the charge controller with a 6p config?
2) What fuses/breakers to use, I'm a bit confused about this also?
3) When laying out a series of panels should I do nearby ones linked that are likely to also be shaded together or kind of spread the series out randomly so only parts are shaded? Trying to understand layout strategy....

Thanks for helping with my newbie questions.
Mike

 

[Rednecktek]

1) What would be the best wiring layout for the panels - originally I thought 6 in parallel would be best but after reviewing fuse posts I became aware it maybe 2s3p or 3s2p similar layout ? Some posts I read indicate I may overload the charge controller with a 6p config?

Well, going 2s3p means fuses on each string or a combiner box of some kind but good shading protection. 3s2p gives you a little better low light charging. Plus going 6p would be honkin huge wire (8AWG most likely) and you're right that your SCC may not be able to handle it.

2) What fuses/breakers to use, I'm a bit confused about this also?

If you go with 3p you'll need at least 3 in-line 15a fuses which is 6 more points of failure. Going with the 2p means 0 fuses. 15a DC breakers are also a viable option, just spend the little extra on a name brand like BlueSea or Eaton and avoid the automotive tube-style breakers. That gives you a handy disconnect for working on the panels in the future.

3) When laying out a series of panels should I do nearby ones linked that are likely to also be shaded together or kind of spread the series out randomly so only parts are shaded? Trying to understand layout strategy....

If you think part of a string is going to be shaded, keep those panels close together so you're not shading parts of multiple strings. Shading part of 1 panel nerfs the whole string so you don't want a tree branch covering parts of multiple strings if you can avoid it.

Your AGM batteries are going to handle the cold better than LFP, and usable watt per usable watt are about the same cost as a LFP battery, it's just lighter and takes up less space.

 

[rawtoxic]

OK that helped a lot. I think I will work towards 3s2p layout with panels series adjacent each other. Just to confirm I don't need any fuse between panels and SCC with this config? Another follow up question is with 3s2p I'm at 24v right? But I think I understand my SCC will convert this to a usable 12v for my battery - correct? I will want to add a simple shut off so I can easily work on panels - maybe like this https://www.amazon.com/gp/product/B0C73LST6B/ ? Should the simple shut be on the + or -?

My battery is a single large 210ah AGM mounted in the spare tire bay of the truck chassis. From my understanding - the breaker from controller to battery should be close to the battery as possible. Would the Blue Sea 7183 285 series be a good choice for this type of exposure? We have heavy magnesium chloride usage on snow and dirt roads in this area it reigns hell on metals and wires. Or should I consider mounting indoors closer to controller or a different style breaker close to battery? I can probably mount it somewhat protected near the battery.

The breakers I want to avoid are this style correct? https://www.amazon.com/gp/product/B08BWM7YH9/ I will say I have one that came with the rig between battery and 750W inverter 60A size. Should I get it replaced? It's never tripped but I do use it to shutoff inverter from accidental usage (it's an area it could be bumped on unknowingly)

Good to hear my AGM might be more suitable for my needs. I would really like to get a better DOD with a lithium but the cold weather usage/charging scares me. Also most self-heating batteries I researched won't take a charge below 10A which also seems wasteful to me along with the heating of the battery aspect does seem like a waste. I do have room underneath the truck to add another AGM but given the one is 3+ years old I probably want to wait until it's life cycle is over and 2 new at once. Any insights into my battery situation would be appreciated.

Thanks again!

 

[Rednecktek]

OK that helped a lot. I think I will work towards 3s2p layout with panels series adjacent each other. Just to confirm I don't need any fuse between panels and SCC with this config? Another follow up question is with 3s2p I'm at 24v right? But I think I understand my SCC will convert this to a usable 12v for my battery - correct? I will want to add a simple shut off so I can easily work on panels - maybe like this https://www.amazon.com/gp/product/B0C73LST6B/ ? Should the simple shut be on the + or -?

Close, your VoC in 3s2p will probably be around 66v. Go for a double pole DC rated breaker that's rated for 25% more than what you need.

My battery is a single large 210ah AGM mounted in the spare tire bay of the truck chassis. From my understanding - the breaker from controller to battery should be close to the battery as possible. Would the Blue Sea 7183 285 series be a good choice for this type of exposure? We have heavy magnesium chloride usage on snow and dirt roads in this area it reigns hell on metals and wires. Or should I consider mounting indoors closer to controller or a different style breaker close to battery? I can probably mount it somewhat protected near the battery.

You always want to place the breakers and fuses as close to the source as possible so it can protect the wire between it and the loads. For a SCC that means close to the SCC, for an inverter that means close to the battery. Mount as much as you can indoors to help with the salt and temperature control.

The breakers I want to avoid are this style correct? https://www.amazon.com/gp/product/B08BWM7YH9/ I will say I have one that came with the rig between battery and 750W inverter 60A size. Should I get it replaced? It's never tripped but I do use it to shutoff inverter from accidental usage (it's an area it could be bumped on unknowingly)

Yes, those are notoriously bad and unsafe. Grab a BlueSea or Eaton or I've even been happy with my T-Tocas brands.

Good to hear my AGM might be more suitable for my needs. I would really like to get a better DOD with a lithium but the cold weather usage/charging scares me. Also most self-heating batteries I researched won't take a charge below 10A which also seems wasteful to me along with the heating of the battery aspect does seem like a waste. I do have room underneath the truck to add another AGM but given the one is 3+ years old I probably want to wait until it's life cycle is over and 2 new at once. Any insights into my battery situation would be appreciated.

Cold weather is the biggest reason to go with lead acid flavors unfortunately. Some self heated batteries switch incoming power from the battery to the heaters and back based on temperature, and some feed the heaters from the battery. You'll have to dig deep into the specifics of each brand to figure out which does which. I'm not that familiar with the inner workings of each make & model, that's more of a @Will Prowse question as he's torn so many apart.

Thanks again!

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