The researchers in this project, at UC Merced and UC Davis, have set up two experimental solar stations, one on each campus, that are equipped with highly sensitive instruments that can independently measure direct normal solar irradiance (DNI), global solar irradiance (GSI), and the total combination of the two (called local global irradiance). The solar data collected at those ground stations are being correlated with several kinds of satellite image data—on weather, aerosol and ozone content in the atmosphere, and other variables—as well as ground radar information about local atmospheric conditions. Armed with the ability to forecast accurately, utility companies and policy makers will be able to invest confidently in California’s abundant solar energy opportunities.

Merced professors Carlos Coimbra’s and Qinghua Guo’s Solar Irradiance Mapping Initiative is an important and successful project put into motion with the help of seed funding from CITRIS. This was launched with a $75K award from CITRIS and is now funded for with $1M from the CEC and more than $560K from the NSF.

The Solar Irradiance Mapping Initiative (SIMI), a collaboration between Professor Carlos Coimbra and Professor Qinghua Guo of UC Merced and Professor Jean-Pierre Delplanque of UC Davis, is attempting to provide that predictability. Professor Coimbra deployed solar observatories at the UC Merced and at the UC Davis campuses equipped with high-grade instruments to measure local global, diffuse, and direct normal irradiation redundantly, as well as other relevant weather quantities. He correlates data from the ground stations with radar, geo-stationary and hyper-spectral satellite data. The resulting model incorporates features of the specific atmospheric conditions (aerosols, vapor content, cloudiness index) that are characteristic of the region.

Coimbra and his colleagues are finding novel ways to combine satellite and ground data about irradiance, and to hybridize them into predictive models. Based on neural networks and algorithms, the likely global solar irradiance at any given time, on any given day, in any given season will be predicted. The project won a seed grant from CITRIS in 2007, which, Coimbra says, “allowed us to move from just talking about this to actually doing it.”

Today, three years later, Coimbra’s research is supported by the California Energy Commission and the National Science Foundation, among other sources.  Moreover, he is using his improved forecasting results to help manage energy loads on the UC Merced Campus. Ultimately, this research could influence the state’s ability to make solar-workable scales that could improve California’s energy picture. Accomplishing that will lessen citizens’ and businesses’ reliance on expensive oil, and reduce the emission of CO2 and other greenhouse gases.

Storage of renewable energy poses another significant challenge as the share of renewable energy sources feeding in to the electricity grid increases. To be practical, energy sources such as solar energy, which is only generated during the day, must be stored in a way that is both efficient and itself environmentally sustainable. At UC Santa Cruz, CenSEPS is exploring the social impact of new renewable energy technologies and helping a new generation of engineers to address the challenge of more efficient energy use with a minimal carbon footprint. The CenSEPS project: Engineering and Societal Investigations to Initiate Renewable Energy for the Santa Cruz Municipal Wharf has recently been awarded a CITRIS seed grant. The goal of this project is to make the Santa Cruz Wharf “smart-grid ready” and to create a sustainable power system that would serve as a prototype for other coastal communities.

Picture of the Day, February 25, 2011
Carlos Coimbra working at his solar research facility at UC Merced as part of the Solar Irradiance Mapping Initiative project.