Adding 2S to existing 2S2P array?

[dixonge]

So I have an existing array of 100W panels in 2S2P configuration. An additional couple of panels might be in my future. I would likely wire them in serial, but it is possible they will not be on the roof with the other panels, but will, instead, be portable on the ground. In this case I would be connecting them in the battery bay, not on the roof with the others.

Does this change the configuration and fusing requirements? Wouldn't this be a mismatch of volts/amps coming off the roof in comparison to the ground panels? Is this even doable? If so, is it recommended? Would it be better to just connect them through a separate SCC? If so, I have an additional PWM - can that be combined w/ my existing MPPT unit?

Apologies for so many questions all in one post....

 

[FilterGuy]

Does this change the configuration and fusing requirements? Wouldn't this be a mismatch of volts/amps coming off the roof in comparison to the ground panels? Is this even doable? If so, is it recommended? Would it be better to just connect them through a separate SCC? If so, I have an additional PWM - can that be combined w/ my existing MPPT unit?

It is doable with proper blocking diodes.... but you have to assume that because of the differences, only one set of the panels will be contributing at any given time. The voltages will be different enough that the old and new panels will not produce at the same time... and depending on how the new ones are set up, they may never contribute to any significant amount.

Where I have heard of different sets of panels on the same controller being usefull is situations where you have a set facing east and a set facing west....In the morning the east panels are producing and in the afternoon the west panels are producing. You may want to take a look at this video from @Will Prowse:

Sooooo.... the best would be a separate controller. As far as I know, mixing a PWM and an MPPT on the same battery will work, but I have never really studied that let alone tried it.