National Semiconductor plans to improve the efficiency of solar panels
Solar electric panels convert sunlight into electricity, but unfortunately their efficiency can fall rapidly at lower light levels. In practice, if only a part of a solar panel is shaded, the entire array's output can be considerably reduced. Analogue IC specialist National Semiconductor says it has come up with a new technology that will help.
The problem has to do with the way panels are arranged in a string. Whether on a building or in a field, a row of panels is connected to a single inverter that converts the direct current generated by the cells, into alternating current. If part of that string of panels is shaded and therefore only produces little electricity, the entire output of the string is reduced accordingly; the weakest panel determines the efficiency of the process. In some cases, the inverter does not even get the minimum amount of electricity it needs to operate. Then, all of electricity produced by the unshaded panels in that string is completely lost .
Researchers have therefore been looking for ways to equip each solar panel with its own micro-inverter. The problem is that any design changes made to the panels have to withstand heat, cold, rain, and snow for decades. Now, National Semiconductor says it has come up with a technology called SolarMagic that can withstand the elements. Each individual solar panel in a chain is fitted with a SolarMagic module to compensate for fluctuations in voltage from shading caused by, for example, dirt on the panel, or dead leaves. 40 per cent of the energy that used to be lost due to such shading is expected to be recovered. National says these micro-inverters will make panels 10 per cent more expensive. SolarMagic is currently being tested and is expected to hit shelves in the first quarter of 2009.