PV Generation Potential for August 2014

By Adam Kankiewicz

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. In addition to the monthly PV Power Map, this issue also includes a PV Power Variance Map, which highlights how energy production in August 2014 compared to the typically expected August energy-production profile.

The PV Power Variance Map was created using PV simulations based on 10-kilometer SolarAnywhere typical global horizontal irradiance (GHI) year (TGY) data, which is composed of average month satellite-derived solar resource data from 1998 through 2013. The PV Power Variance Map shows the percent difference between PV energy production in August 2014, and August TGY data.

As illustrated by the August PV Power Variance Map, above-average PV energy production was realized across the southeastern and northeastern United States due to dry conditions over the regions. Above-average PV energy conditions also dominated western regions of Oregon and Washington, while wetter and cloudier weather resulted in below-average PV energy production over the interior Northwest and into the upper Midwest.


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.

For example, a 4-kW system in Portland, Oregon, would have produced approximately 600 kilowatt-hours during August (150 kWh x 4 kW = 600 kWh), which was approximately 17 percent above typically expected August production.

To gain an understanding of the production of a particular system over a period of time, you can view historical PV Power Maps from 2012, 2013, and 2014 at solartoday.org/pvpowermap.

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.

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