Typically how many times a year does an array need to be cleaned? I realize each area is different. How much snow, leaves, dirt and bird droppings would keep a module working at one hundred percent?
Cover glass coatings that repel the adhesion of dirt are something I seem to recall seeing touted here and there. The idea is that rain or wind washes or blows it all away because it doesn't really stick. Whether 'most modules' have such coatings nowadays is not something I can't speak to though.How is that? Cleaned by rain is not the same as "self cleaning", and how would more recent manufacturing methods make a difference?
How is that? Cleaned by rain is not the same as "self cleaning", and how would more recent manufacturing methods make a difference?
Hydrophobic nano-coatings are specific to water, and I don't know that they would be transparent enough to UV not to detract from the module's performance. At any rate, I know of no module manufacturers who are using it.It all has to do with coatings that they apply to the modules, the best right now would be a hydrophobic nano-coating. you can google it and read about it. there is a lot out there on it. it does not really clean the module but makes it so that items do not stick to it.
They do. See http://www.solarpowerworldonline.com/2015/01/411-frameless-solar-modules/If they could make panels with no metal frame, like frameless glass... they would clean better in all cases!
That may or may not be worth the trouble; tilting at latitude may be nearly as good, and adjustable tilt racking is more expensive and more vulnerable to wind loading. Make a few PVWatts runs to show the differences.If I did it again I’d make the vertical angle adjustable so I could go steeper in winter and lower in summer... better production.
This is done quite often; more modules is usually cheaper than a tracking system.The other thing I’d do is add maybe 15% of panel area looking direct east and the same direct west so that in the morning, when the main array was at low angle and low production, these extras would give an early boost and same in evening. I would not overpower the inverter because at mid day, when main array is at peak these morning and evening additions would be virtually shut down due to angle. Sort of like a tracker but with no moving parts.