National Semi Solar Retrofit Of Housing Project Increases Energy Harvest By 22.6%

July 14, 2009 by Jeff Shepard

National Semiconductor Corp. announced the retrofit of an affordable housing project in Oakland with its SolarMagic™ power optimizers, boosting the electricity production by 22.6%. The 30kW solar system sits atop the Oak Street Terrace, a 39-unit affordable housing development specifically designed for low-income seniors.

Completed in 2005, the multi-story apartment building was initially designed to be as energy efficient and eco-conscious as possible, and is constructed out of recycled and natural building materials. Jigar Shah, founder of SunEdison, installed the solar system and is providing the power generated through a power purchase agreement, where residents lock into a low, fixed-rate for electricity.

"For over four years, our Oak Street installation has been helping residents pay less for electricity, and the addition of SolarMagic has dramatically boosted system performance," said Jigar Shah. "SolarMagic is helping us get 22.6% more power out of the same panels, making the system even more productive and cost-effective."

Due to environmental and system efficiency factors, all solar installations provide less energy than the maximum rated output of the solar modules. This difference is called the "performance ratio." The industry average performance ratio is 75 to 80%. After a period of monitoring and evaluation, National Semiconductor found the performance ratio of the Oak Street site had degraded since installation from 77 to 67%.

While the site was equipped with a state-of-the art monitoring system, National Semiconductor found that there was an unrealized gain of 20,000 kilowatt hours. In March 2009, National optimized the system performance and retrofitted approximately one-third of the 204-panel system with SolarMagic power optimizers. Subsequently, the performance ratio of the site improved to 82%, an overall improvement in power output of 22.6% – well in excess of its forecast production rate.

"Real world conditions such as shade, aging and panel mismatch can significantly degrade the performance of a photovoltaic system," said Ralf Muenster, Director of National Semiconductor’s Renewable Energy Segment. "With National’s SolarMagic power optimizers, the true potential of these systems can be realized."