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Attached is a graph that I produced to document the effect of various ratios between the PV array size and the inverter size. I extracted output power data for a 1020-watt system located in NE Oregon that is on the Sunny Portal. The data are publicly accessible so feel free to run your own analysis. Better yet, analyze the data for a system near you. Using 2009 data, I looked at how much energy would have been lost if the output was clipped at 800W, 810W, .... 1020W. I used 2009 data because there was a period in 2010 when the Sunny Webbox didn't have internet access. At 800 watts, power clipping would have happened on about 25% of the days. Yet the energy that would have been lost was only 0.38% of the annual total. The results shown on this graph aren't universal, results would be a little different in 2010, it would be different in some other climate, it would have been different at another elevation, it would be different with a different array angle, ..., and the module tolerance and inverter efficiency also effect the results. Modules in this system are Suntech 170-watt +/-3%. The inverter is Sunnyboy 1800 that should be operating at close to 93% efficiency. Kent Osterberg Blue Mountain Solar. Inc. |
ClippingDataAnalysis.pdf
Description: Adobe PDF document
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