East/West array inverter setup
I am doing an East/West Array. Do I need two separate inverters or an inverter with at least two MPPs? How does production stack up between these options?
We are continuing to see an increasing number of East/West arrays because of the drop in module pricing and more Time-of-Use (TOU) rate designs. Grid operators may prefer E/W arrays since the power produced is more even throughout the day versus Southern Orientations. Fronius recently completed a study that shows that it is NOT necessary to have two inverters or two MPPTs in E/W arrays.
It was expected that because of module mismatch two inverters, or at least two MPPTs, was necessary for E/W arrays. Fronius’ study found that while the current differed between the East and West Arrays, the voltage was almost identical. This resulted in annual energy loss of less than 1%, but the inverter will operate in a higher efficiency range for a longer period. You will still want to follow basic installation rules--even strings, same inclination angle, no shading, etc., but there should be no disadvantage to having one inverter and MPPT.
Its worth noting that most modern string TLs are now equiped with at least two MPPTs.
Don't forget to make sure that strings have all the modules facing East or West. Don't mix the modules in the string. During install and commissioning it's not uncommon to find strings mixed.