Adding panels to an existing array

[Kerry]

I hope this is not too simple, but I can't fins the answer with google...

I have 24 Aleo s-18 225 watt panels hooked to a SMA SB 7000 in 3 8 panel strings. I would like to add more panels, but the original supplier/installer is not an option. The question is: If I buy 225 watt panels from a different manufacturer, are they going to be compatible if they have there own string? Are they going to drag down the rest of the system because of voltage differences?

I understand that I can add more panels if I add a new inverter, but the inverter that I have has alot of capacity to spare. And I would rather not spend the money on a separate one if I can get away with it.

Thanks for reading

[Mike90250]

Depends. If the inverter has SEPERATE MPPT controllers, then you can hook any compatible string to the other input. If there is only a single MPPT controller, then all the strings should be matched, or performance will suffer as the inverter hunts for a sweet spot that does not exist.
The closer you can match the string voltages, then the less loss you will have.

[solar_geoff]

If you can find modules with a very similar I-V curve it would work OK... But if not its pretty much its not going to work even if you have an entire string of the new mod. By having a different type of module you will be outputting a completely different voltage which will not allow the invereter to find a consistent max power point. Production would suffer heavily.