I’ll pass this along as a public service, since EVERY website I visited asking this question got it wrong. Nearly every website I visited on whether or not it’s worthwhile to have solar panels professionally cleaned said it wasn’t necessary.
The solar panels on my roof would get dirty over time – dust, pollen and the like. Usually I’d just wait for a rainstorm to clean ’em off and return them to their shiny dark blue reflective look, instead of a dusty car finish look. Sometimes I’d hose them off early in the morning after morning dew had loosened the dust and they weren’t heated up yet. After I’d clean them, I’d notice an uptick in performance when reading the numbers on the inverter.
Recently, I noticed my system had dipped in performance, and the panels were pretty dirty – and hosing them myself didn’t really make much difference. Never mind that my hose added hard water marks.
So I hired a local dude to climb up on my roof and clean them with ionized water and a soft mop. Not very expensive, and it only took him an hour or so. He also tightened the clamps and zip ties on the panels, as well as the added bonus of replacing a cracked roof tile for me I had NO idea about, all gratis!
That’d be enough for me to recommend the guy to locals, but the big news is that cleaning the panels did the trick – they’re back to producing the amount of energy they’re supposed to.
The weather has been identical, and the cleaning made a 15+% difference in the efficiency of the system.
So THE WEBSITES TELLING YOU OTHERWISE ARE CRAP. Your mileage may vary, but cleaning the panels will definitely restore the normal efficiency of your system if you see it significantly dipping due to the dirt.
For real numbers – the total kwh/day varies with time of year, but peak production @noontime- 1pm or so is a good metric. My system, on a clear day, will peak anywhere from 3 to 3.2 kwh. It had dipped to 2.6 – 2.7 with the dirt. Now it’s back to 3 to 3.2 with the cleaning.
Battery backup is also on the way. I do not enjoy sweating whether or not those scumbuckets at the electric utility will turn off my power during wind events to cover their ass for fire starting lawsuits.
I’ll practically be off the grid! Here’s a recent picture, too!