Covers simply will not work. They will reduce light throughput significantly.

Consider a 100 Megawatt electric net output (average per day, 24 hour rated) power plant (not large by today's standards). Assuming 300 watts per square meter peak power after all losses (resistance, transformation, storage, etc) are taken into account, and a load factor of 1/3. It cannot be higher than 1/3 because of the fact that even if it is completely cloudless, night knocks out 50% of the 24 hours, and low azimuth will reduce input when the Sun is not high in the sky.

Under these assumptions each square meter produces an average of 100 watts of power on a 24 hour basis. For 100 megawatts, one would therefore need one million square meters of photovoltaic area. No "few workers" are going to keep that large an area clean.

It will take motorized wipers with detergent sprayers operating frequently. Assuming that each wiper takes care of ten square meters, then 100,000 wipers will be required. Each cleaning cycle for each wiper will require at least one liter of water. If each wiper runs only once per day, that is 100,000 liters of water per day. That is not a great deal, but it must be trucked out to the desert or sent by pipeline. To that at least 1% detergent must be added to get the job done properly. Periodically, the wiper blades must themselves be rubbed down with a mild abrasive to keep them effective. They must be replaced one every year or two.

Finally, one decent sandstorm and the PV surfaces need to be polished to remove the "frost" (actually pitting) caused by the sand. This is not going to be a trivial operation. Each polishing operation removes material and eventually, the entire surface is removed down to the bare PV material, and then beyond.

Are you beginning to see the scale of operation that is required to keep the PV surfaces working at peak efficiency?

David F Mayer