Adding panels

[N1UB]

I have a system that uses a Classic 150 and a pair of Trina 255 panels. I have found a good price on a pair of Solarworld 260's. Would this be a problem to add into the system with a slight miss match of panels in a separate string ? My panel wiring is <10' and goes directly to the E panel.

Thanks, Bart

[ClassicCrazy]

I added some panels of a different type to a friends system and had the same question. You need to keep the voltage Vmp  of each string within a certain percentage of each other ( I forget what percent that is now) . Otherwise the MPPT won't work correctly.

Here is a discussion that someone asked about adding panels.

http://www.midniteforum.com/index.php?topic=793.5%3bwap2

[Westbranch]

keep the voltage Vmp  of each string within a certain percentage of each other

the rule of thumb used for percentage is  +- 10%....
In parallel connections it is the Vmp that makes the difference.
In serial connections the important number is the Imp .

hth