It's not always cloudy in the Pacific Northwest: Characterizing the solar resource and solar irradiance variability

The frequent cloud cover and high latitude of the Pacific Northwest often cause it to be disregarded in discussions of solar power generation. However, climatology across the region varies substantially: for example, some otherwise cloudy areas typically experience long summer days with up to 16 hours of daylight. This poster presents results from our study of five-minute solar irradiance data over twelve years and five sites. The sites spread from western Oregon to southwestern Montana, with elevations from 150 m to 1500 m and climate zones ranging from wet lowland coastal to semiarid high plains to intermountain valley. The monthly and yearly solar resource availability is discussed and compared to national and international locations with existing solar power plant infrastructure. Short-term clear-sky index variability on time scales ranging from 5 to 60 minutes is analyzed, with clear-sky index values estimated using the Long-Ackerman technique (JGR, 2000). Observed differences in overall resource and clear-sky index variability across sites and timescales are discussed in the climatological and meteorological context of each region. The potential output of a system of solar plants in the Pacific Northwest is calculated by averaging the observed clear-sky index data, resulting in smoothing of the overall variability.

Data provided courtesy of the University of Oregon Solar Radiation Monitoring Laboratory.

Long and Ackerman (2000), J. Geophys. Res., doi:10.1029/2000JD900077