Here's the ash that we're trying to clean up. Enough collected on our solar panels for me to collect some as a souvenir. A lite dusting looks whitish grey, but a pile of it shows its true color -- moderate ashy grey.
First of all, "W" directed us to a pressure washer that he thought would work with our marine pump.
By using a different hose than we normally use ........we hooked up the pressure washer using a 25' hose, 1" diameter hose.....the washer works just fine. A standard 100' 5/8" garden hose couldn't deliver enough water fast enough. This is a small pressure washer but it is doing a good job for our needs. We were able to clean the solar panels fairly well.
It blasted the black ohia tree gunk off, and it appeared to take the ash off too. But when the panels dried, they still had a light covering of ash. That ash is really persistent. So we moved on to the next suggestions. Many people suggested hardwood floor mops. And one friend actually presented us with a gift of a mop this past weekend. It's a flip mop for hardwood floors. We gave it a try......
Worked super!!!!! Having blasted off 99% of the ash, the mop was able to clean the panels the rest of the way.
Thanks everyone for your suggestions!