By ADAM KANKIEWICZ March 19, 2014
The PV Power Map is a report of national solar resource availability as illustrated by the monthly energy output of a nominal 1-kilowatt (kW) photovoltaic (PV) system by location. This issue features a map of the average monthly PV power output in 2013, and a figure that illustrates monthly PV power output variances from the typically expected monthly production. As can be seen in the figure, annual averaging tends to smooth out significant monthly variability.
Overall, 2013 energy production reached expected potential at most locations across the United States. Most of the desert Southwest saw near-to above-average PV production due to the extended drought that is affecting the region. The Midwest saw near-normal PV production, while the Southeast experienced less-than-average PV production in 2013.
Month-on-month variance in PV energy production can be significant with respect to long-term monthly average production. This figure compares actual monthly production in 2013 to SolarAnywhere Typical GHI (Global Horizontal Irradiance) Year (TGY), which is calculated using data from 1998-2012. As shown in the figure, while monthly production swings as high as 10 to 25 percent occurred throughout 2013 at four U.S. locations, the annual variance in PV energy production was significantly reduced. This is generally the case, with annual variance rarely exceeding five percent.
The PV Power Map can be used by anyone to quickly gauge the generation potential of a new PV system, or benchmark the performance of an installed system, in a given location. Simply multiply the power output indicated on the map by a project’s capacity, in kilowatts, to calculate the total estimated power output for the month.
To gain an understanding of the production of a particular system over a period of time, you can view the most recent PV Power Maps.
The PV Power Map is created with power output estimates generated by SolarAnywhere services from Clean Power Research; these include simulation capabilities and hourly satellite-derived irradiance data with spatial resolutions from 1 to 10 kilometers. The calculations are based on a PV system with a total 1-kW nameplate rating that is configured as five 200-watt PV panels with a 1.5-kW inverter; fixed, south-facing panels with 30 degree tilt; no shading; panel PVUSA Test Conditions rating of 178 watts; and inverter efficiency of 95.5 percent. Access free historical irradiance data at solaranywhere.com.
Adam Kankiewicz (askcpr@cleanpower.com) is a research specialist at Clean Power Research.