At $150 per cleaning, you have to be hustling a lot to sell enough jobs to make a profit, especially when the upfront equipment costs of a van rigged up to power water and the drone are factored in! How is a crew of 4 working together on each job able to make $50-$70 per hour?
If you are doing roof and solar panel inspections, your only overhead is your time and the drone, and you can outsource the panel cleaning to these guys for a referral fee, if needed.