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miguel-d asked

Poly vs Mono Panels and MPPT Controller on a camper van

Hello,

I have a camper van with a 12V system powered by a single 150W Poly Panel (not from Victron) controlled by a MPPT 75/15. Now I want to upgrade and I'm thinking about selling the current panel and controller and get two 175W Victron solar panels (in parallel).

My first question is regarding the cell technology that I should go for. The 175W Mono and Poly Victron solar panels have the same size and the price is very similar too. I can't find anything on the datasheet regarding the efficiency but I read that the mono panels tend to work better on low light situations while poly work better in shaded conditions (scattered rays).

Should I go for one of each to have the best of both worlds? Or should I go for 2 Mono since it will give me the best performance in full sun and low light conditions (the conditions that I will have maybe 98% of the time).

My second question is regarding the new controller. The MPPT Calculator gives me the 100/20 option, but its datasheet says that the Nominal PV power at 12V is 290W and the new system would give me 350W at the peak. Is the 100/20 controller a good option? Will I be able to take full advantage of the system with it?

Thanks for the help!

MPPT ControllersSolar Panel
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spirou avatar image spirou commented ·

Realistically, the panels will rarely if ever produce enough to reach the 20A limit unless you're chasing sun all the time. But if you want to play it safe then get the 100/30 model (what I have with 2x160W). Poly or mono is largely irrelevant IMO. There might be a bigger difference between two panels of the same type than between different types. I know mine are terrible in winter low light when I need them most. On the previous van I also had a poly panel (1x120W) and it seemed to handle itself quite a bit better than these two now.

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miguel-d avatar image miguel-d spirou commented ·

I live in Portugal so, specially during the summer, sunny days are a constant. If I get more than the 290W with the 100/20 what happens? Does the fuse burn or it caps out the charging power at 290W? I cannot understand why the calculator suggests the 100/20 controller to a system capable of doing 350W. Am I thinking something wrong or should the calculator suggest the 100/30 instead?

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neoneddy answered ·

Don't do two different types. The MPPT will track to sweet spot of the lowest performing panel. So you'll effectively have two Poly panels in performance if you do split.


I've got a larger array on my bus at 1950 watts. I find myself having partial shade quite a bit. It doesn't take much to put them in shade mode (like a grapefruit sized shadow). I'd go with whatever option lets you buy the most wattage of panel. Even adding more. You can never have too many IMHO.

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