There are guidelines to estimate output, but as Jason says everyone will use different figures. It’s nothing to do with more down time, more to do with different assumptions. There are so many figures to calculate output, starting with solar irradiance, and assumed derating, the actual panel and inverter derating are a very small part of that equation. I would say Everything Solar are probably just being more conservative.
Is this the Melbourne based Everything Solar? I thought they were wholesalers, and their retail arm was called Solar Sunworx. Has that changed? They’re a pretty good mob if it is them.
See more details on Florida solar power in this post:
Marty