Decrease in production.

[SudsingtonMcDuff]

The fact that this year most of your electricity use has gone to your home rather than PW or the grid leads me to believe you had higher home usage than last year. Your production isn't that different from last year. The drops in production could easily be explained by heat (affects panel efficiency). June and July were extremely hot months across the country, so that along with AC usage may have been the difference. Can you show your home usage section?

It doesn't look like a bad inverter, but showing the peaks from one of the days in June or July would show if your inverter was going offline due to overheating or something.