I thought about this but decided against offering the service just at the moment:
1. Many I have looked at are on roofs where I would need a much bigger pole than the SLX25 I have now. That's gonna cost and the potential customer base is still a bit small, but granted is growing.
2. Many of the houses i've seen them on I wouldn't be able to reach no matter how big a pole I have - I wouldn't be able to walk back far enough to enable the brush to make contact with the panel. This further reduces the customer base.
3. I've worried about damaging them, or at least being held responsible if they fail in some way post-clean. Insurance for such claims should there be any would be an additional expense, increasing further the length of time to break even.
I'd be interested to read on how others are finding cleaning them as i'm not ruling it out in the future.