Also posted as a question on Sustainability.SE – EnergyNumbers Jun 8 at 19:28

If they are installed on a tilt, or do not live in an arrid zone you shouldn't have an issue. Standard rain will clean them off as often as they need to be cleaned. If they're flat, the lip on the frame will keep water on them which, when it evaporates, leaves dust - in that case, honestly, all you need to do is hose them down. – Meeka Jun 13 at 13:03

@Meeka this isn't the place for answers - these are just example questions to scope the site. Vote up the questions that you'd like to see the site address. Vote down questions that you think should be out of scope. If you want to answer this question, please do come over to Sustainability and answer it there – EnergyNumbers 21 hours ago

This is a global forum, members can come from the Southern Hemisphere or the equator. :) – Szilágyi Donát Jan 16 at 22:01

There are many, many monitoring services available. And many state incentives require monitoring on PV projects in order to award grants. Check out locusenergy.com – Meeka Jun 13 at 13:05

This would need to be specific to a particular jurisdiction at a particular time. – EnergyNumbers Jun 8 at 19:29

(Data could be about no. of people opting for/interested in getting powered from renewable energy source, demographics, Tariffs, etc.) – steadyfish Apr 5 at 19:11

You should add to the end of the question: in UK. – Szilágyi Donát Jan 16 at 20:13