Monday, February 23, 2009

New Product Can Mitigate Shade, Making More Roofs Available to Solar

SANTA CLARA, Calif., Feb. 23 /PRNewswire-FirstCall/ -- Most installers of solar photovoltaic (PV) systems (54 percent) believe no amount of shading is acceptable on residential and commercial rooftop solar installations, a new survey shows. National Semiconductor Corp. (NYSE: NSM) commissioned the study to better understand installers' views on the impact of partial or temporary shading.

Due to the characteristics of solar arrays, small amounts of shade (for example, shading of less than 10 percent of the surface area of a PV system) can lead to disproportionate power losses of more than 50 percent. National will introduce a technology later this spring which will allow installers and homeowners to embrace shade and recoup up to 50 percent of power losses associated with partial shading.

Causes of shade include structural objects such as trees, chimneys and dormers, and intermittent debris including falling leaves, bird droppings and dust. In the case of structural shade, even correctly installed solar systems can be partially blocked from the sun at certain times of the day or during certain days of the year.

The survey, conducted by Greenberg Quinlan Rosner Research, found:

* 41 percent of solar installers encounter shade when selling or installing a PV system;
* Of those, 87 percent "frequently" or "always" design around shade;
* Another 28 percent "frequently" or "always" tell the owner that solar cannot be installed

The study also revealed that installers often place smaller solar arrays in order to avoid shady sections of customers' roofs. Roughly one third of installers said designing around shading increases system costs, and many said they lose time doing so. Additionally, nearly half of all installers have seen solar arrays whose performance has been impaired by shading.

"Shade happens, and customers and solar installers are picking up the tab," said Ralf Muenster, director of National Semiconductor's Renewable Energy Key Market Segment. "There is a real need to educate the market that shade does not mean 'lights out' for solar. Shade can be mitigated."

Shade need not be terminal for solar power. While solar cell manufacturers have poured millions of dollars into research and development to improve conversion efficiencies by a fraction of one percent, solving power mismatches from different panels within a single solar array, whether caused by shade or other problems, can yield improvements in system performance of more than 30 percent.

Later this spring, National Semiconductor will introduce its SolarMagic(TM) power optimizer, a new energy management product that will mark National's strategic entry into the photovoltaic market. The power optimizer will enable installers to embrace shade, placing PV systems on roofs previously regarded as receiving inadequate levels of sunlight to justify a solar array.

According to the study, solar installers and integrators appear to be the principal victims of shade as they frequently absorb the costs of shade rather than pass them on to the consumer. Issues for installers include increased installation time and costs, and losing many customers altogether after discovering during time-consuming site visits that their roofs are too shady.

"Many customers are seeing impaired performance from the solar systems in which they have invested thousands of dollars," added Muenster. "Lessening the impact of partial or temporary shading by retrofitting power optimizers will help owners of existing solar systems. But SolarMagic technology will also contribute to the growth of the PV market, allowing the installation of solar arrays on roofs previously regarded as unsuitable."

Muenster added: "Power optimizers will make life easier for installers by giving them more flexibility in where they install solar systems. SolarMagic technology will allow installers to live with shade in a way that previously has been impossible. It will dramatically increase the reliability and maximize the energy harvest of photovoltaic panels in imperfect real world conditions."

The survey of photovoltaic solar system installers was carried out by telephone in January 2009. Greenberg Quinlan Rosner Research spoke to a total of 150 installers across the United States.