Series-Parallel Experts!

[Tyboo]

My 2022 GD Reflection 28bh came with a Grape Solar 370 Watt panel from the factory and as im looking to expand the system it is proving to be a bear to add additional panels, efficiently. I'd like to avoid replacing the existing 10awg from the roof to the controller up front so expanding in series made the most sense at first, however I don't have room for 3 of those 370w beasts and we camp in the woods often so the shading effect of all panels in series makes me nervous. So here's where im at, SERIES-PARALLEL, please let me know what you think. There's lots of theoretical information out there to consider in a setup like this so please double check my work! If you think it's a good idea, then I got lots of inspiration from folks on these forums and Nate over at Explorist.life (Check them out if you haven't, TONS of great info). If it sucks, then it was my idea, i'm the only one to blame.




The 370w Grape is what I already have. They won't ship a panel to me, said the packing for freight would cost 500 bucks before the price of the panel! I found this Furrion 370W gen 2 from Lippert and while it's expensive, shipping is free. The Newpowa 200W panels I found from BattleBorn with free shipping. These panels were designed to expand 24v systems which makes them look to be a better match to expand my system. Anyways, let the darts fly where needed!

[Yoda]

While I am not an expert I was told never to mix panels into one controller - something about a mixed load imbalance. I would tie the two matching 370W panels into one MPPT controller and the two 200W into another.

I am sure the experts will be along shortly
Keith

[Tyboo]

Yoda I always heard that too but as I dug deeper into the specifics I was told that it was the the likely inefficiencies caused by mixing and matching that warranted the caution. But im not an expert either.

[Tyboo]

These were to very helpful resources that led me to believe this was possible, I called the folks over at battle born and Victron and they, too, said the concept would work.

https://www.explorist.life/using-mis...r-panel-sizes/

https://www.explorist.life/how-serie...mps-and-volts/

[Yoda]

These were to very helpful resources that led me to believe this was possible, I called the folks over at battle born and Victron and they, too, said the concept would work.

https://www.explorist.life/using-mis...r-panel-sizes/

https://www.explorist.life/how-serie...mps-and-volts/

Check out Will Prowse https://www.youtube.com/@WillProwse He has a lot on setting up solar panels. I like a lot of what he has to say.

[howson]

Tyboo

Only issue I see is the diagram's label has the Impp and Vmpp backwards (the sum above the solar controller where everything comes together).

Yes, what you have should work fine. Remarkable that the two completely different panels have such a close Vmpp even after being combined in series. Since those two series combinations are in parallel, the amperage is additive (as you've done).

It will be interesting to read how this works in the real world. Please post some numbers once the system is operational.

Howard

[Country Campers]

Tyboo

Have a read of this thread Solar Install, Reflection 29RS Fifth Wheel - Grand Design Owners Forums (gdrvowners.com). You could leave the factory 10 ga and solar controller set up in place and add another solar wire chase down behind the hutch similar to what I did. ncitro did this as well in his 28BH, that is where I got the idea for my solar chase. Just adding on to your "thinking". Plenty of different ways to get this done.

Brian

[Tyboo]

Tyboo

Only issue I see is the diagram's label has the Impp and Vmpp backwards (the sum above the solar controller where everything comes together).

Yes, what you have should work fine. Remarkable that the two completely different panels have such a close Vmpp even after being combined in series. Since those two series combinations are in parallel, the amperage is additive (as you've done).

It will be interesting to read how this works in the real world. Please post some numbers once the system is operational.

Howard

Good catch, totally missed that. Ya I was very surprised to find these, almost seems too serendipitous that the math would work out, very curious to see how it does. Before buying and trying I just wanted to make sure there wasn't an obvious reason that I was missing as to why it wouldn't work, I don't read about many rigs wired series parallel. Anyways, I figure I'll try it first. If it doesn't perform then I'll pivot and run two systems like Country Campers and Yoda advised.