Where I live we don't get much rain, have a lot of dust, and I have a pine tree next to my house that sheds sap onto the panels. That means they get pretty filt

Where I live we don't get much rain, have a lot of dust, and I have a pine tree next to my house that sheds sap onto the panels. That means they get pretty filthy over a year. I pay a guy $150 once a year to come clean them off. The gains are marginal, I'd have to do more research than I feel like doing to get hard numbers weighted against weather conditions, but I'd guesstimate around 300-400kWh more output per month. SDGE gives me $0.3-0.5 per kWh during solar peak, so I'm breaking even after one month, and it makes the house look nicer, so I'd call that a win.