Can I add 400W panel in series with existing 2P 100W's?

[the.vandersons]

Hi,

I'm upgrading my van's electrical to lipo batteries. 12V 400Ah Lipo in total.

So I'd like to also upgrade our 200W of solar.

I was thinking to replace the two 100W panels, with two 200W panels, but I was wondering:

Can I keep the 200W I already have in parallel, and after them put in series a new 400W panel? I thought it might not matter that they're different panels if they're in series and the combined voltage is within the range the solar charge controller can accept.

Then I'd need to upgrade the solar charge controller, but I'm okay with that.

Otherwise I'll just go ahead and ditch the old two 100W panels, which have been great! (from the Renogy Solar 200W Kit)

Thanks,
Danny

 

[400bird]

Without knowing the specs, no. Not unless you're ok with the 400 watt panel being limited to what the 100 watt panels are doing.

You could add another charge controller to run both the 100 watt panels and the 400 watt panels separately.

 

[Hedges]

You can put things in series if they are of similar current. Make sure total Voc doesn't exceed equipment limits, even in cold weather.

A problem with two in parallel, then one in series, is if one of the parallel panels gets disconnected and other one gets shaded, the higher amperage panel will push 2x the current lower amperage panel's diode can handle, might burn that up and break the panel.

So while you might get away with it, I'd advice against.

PV panels can be cheap, we've bought some in the $0.10/W to $0.20/W range. Shop for what fits the application best, repurpose the old ones for battery maintenance or something.