Guest post by Roy Van Cleef, New England Clean Energy Technical Sales
I generally tell customers that regular rain showers in New England keep solar panels clear of dust and pollen. But after a recent, particularly heavy accumulation of pollen on every exposed outdoor surface, I was curious as to the specific effect of the pollen on my daily solar production. I have micro-inverters, so I can monitor the production of each individual panel in my 18-panel array.
Early in the morning recently, I went out and hosed down six of my panels, which had a dramatic visual effect (see photo at left). But what was the actual effect on production? At the end of that sunny day, I looked at how the clean panels had performed relative to the unwashed panels. The clean panels produced on average 0.7% more than the pollen-coated panels.
To put this in perspective, a 5-kW array may produce about 30 kilowatt-hours (kWh) on a sunny day. A 0.7% increase in production would be an additional 0.21 kWh per sunny day (.007 x 30 hours). That may have been enough energy to offset the electricity required to run my well pump for a few minutes while I ran the water to clean my panels. But then again, maybe not.
How many days a year do we actually have pollen on the panels? Being generous, we’ll go with 10% of the year, or 36 days. If all those days happen to be sunny, the total production loss over the year is 7.56 kWh (36 “pollen days” x 0.21 kWh per day), out of the 6,000 or so kWh the system will produce.
Let nature take its course.
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