Solar PV capacity factors in the US – the EIA data

Solar PV capacity factors in the US – the EIA data | Energy Matters



A post I wrote a little over two years ago concluded that solar PV capacity factors in the US ranged between 13% and 19% with an average of around 16%. Recently, however, the US Energy Information Agency published a table showing an average capacity factor of around 28% for utility-sized PV plants in the US in 2015. This post looks into the reasons for this large difference and also addresses the question of whether the EIA estimates can be used to predict future US solar PV output.

It concludes that the EIA estimate for utility-scale plants is probably overstated by several percent and that the overall capacity factor is further overstated because the EIA does not take smaller (mostly rooftop) arrays, which have a significantly lower capacity factor, into consideration. Assuming that future PV plant construction in the US is evenly split between utility-scale and “distributed” installations, and that large plant construction takes place all over the country and not just in California, an overall capacity factor of around 20% would be a reasonable assumption for planning purposes.



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