This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).
This project, building and testing an Affordable System for Solar Irradiance Sensing and Tracking (ASSIST), proposes a tiered-architecture where a small number of expensive and highly calibrated observatories get complimented by a larger number of inexpensive, but uncalibrated, ASSIST nodes. Integrating economic stand alone wireless global irradiance sensors with a new dome sensor that avoids having costly moving parts and automatic solar trackers (ASTs), ASSIST nodes should adapt to the vagaries of wireless communication channel, as well as possible failures of many nodes in the ensemble. The work responds to a major obstacle in developing policies that promote and take advantage of existing solar technologies, that of lack of reliable data for ground solar irradiance (direct normal and global irradiance). Despite well-defined and easily calculated radiation reaching outer layers of the atmosphere, solar irradiance reaching ground level (where thermal and photovoltaic solar collectors operate) depends strongly on localized and complex atmospheric conditions. Hence, distributed, embedded environmental sensor systems now enable scientists and engineers to observe environmental systems with previously unattainable spatio-temporal resolution. The vision of sensor systems coupled with 'smart' networking, integrated with visualization tools by an overarching cyberinfrastructure is shared by disciplines actively engaged in solar irradiance monitoring all over the world, and is likely to be realized when such systems are developed ahead of the observatory efforts. The system, developed and tested in the heart of California's Central Valley, is coupled with well-characterized infrastructure-rich solar observatories already deployed. ASSIST aims to serve as a model sensor and information technology system for directly and quantitatively observing the effects of cloud cover, aerosol content, and the presence of participating gases in the lower atmosphere (water vapor, carbon dioxide) and in the stratosphere (ozone), all of which can reduce the availability of direct isolation at ground level to a small fraction of the solar irradiance that reaches the upper atmosphere. From the operational standpoint, the balancing of supply and demand peaks in the electrical grid requires detailed consideration of the availability of solar power as US embraces a more renewable profile of energy utilization. Thus, forecasting the available insolation enables information technology for the success of any policy to include power to the power grid. Engaging students and researchers, this end-to-end sensor system supporting the observatory scale science in solar systems science provides a well-characterized, science-driven design test-bed in a minority-serving university
Broader Impacts: This project enables engineers and scientists to quantify DNI data at spatial and temporal scales currently unavailable. The work develops distributed instruments that are self-configurable, without the need of expensive and difficult-to-maintain mobile parts, and significantly less expensive than current instruments in solar observation technology. The system will be utilized for student experiences; it provides access to important data; and its findings may be adopted by other observatories. In addition to an expected major impact on environmental, CS, electrical, and mechanical research and education directives, the project services student in a minority-serving institution.
