Edison was once heard to say he would ‘put his money on energy from the sun’. An interesting insight circa 1931. And it should come as no surprise to anyone in the engineering community that solar power is the “focus” of a lot of semiconductor, electronics and mechatronic attention. This could be for a number of very good reasons. Such as;
1) Solar cell manufacturing was using so much silicon in 2008 that there was actually enough pressure in the marketplace to cause price increases for silicon wafer. Of course, as with all things electronic, the industry has responded and sufficient supplies have levelled pricing. But the market is expected to reach $22B by 2012, which isn’t too far away, so silicon will continue to have high value.
2) For semiconductor manufacturing machinery makers, Applied Materials especially, markets with double digit growth opportunities attract a lot of attention. So much attention, in fact, that solar manufacturing processes and machinery are the top focus of everyone’s list of things to do.
3) Billions of dollars of funding are being invested to increase the efficiency of solar panel technology from the dismal 8% – 11% range for low quality panels to 12% – 14% for high performance cells and potentially higher efficiency for Copper Indium solar cells. Large scale solar concentrators have achieved efficiencies of 33% but the systems are not suitable for residental or local use.
4) Emergence of many new applications in the “balance of system” products that are necessary when putting a system together. Inverter technology is necessary to convert the dc output of the solar to 120Vac for residential use, or 3 phase 480V for commercial use. Since the inverter is based on transistor technology, this is another huge market application for semiconductors that ends up competing for the silicon itself.
The major mechatronic challenge is keeping the solar cells, and solar concentrators pointed at the sun. Which turns out to be no small task. Solar tracking is particularly important because keeping the solar panel perpendicular to the sun increases the output energy harvest by 25% to 35% depending on the type of system used. This increase is far more valuable than anything happening in the physics lab to increase the efficiency of solar energy.
The nice part of solar tracking for conventional photovoltaics is that the accuracy requirement is not very precise. And since the PV panel is following the sun in it’s patch, the speed is slow, position updates can be done every few minutes, and it’s only on during daylight hours. For concentrating systems it’s a lot more complicated since the sun’s energy is being reflected to a target. Very slight misalignments can have catastrophic results, so accuracy and speed of updates are much more critical.
The geometry problem is pretty complex too. Each location on the Earth’s curve have different ranges of motion. So there are two axes of motion, azimuth which is the daily motion from sunrise to sunset, and elevation angle which varies over 365 days as the Earth’s orbit changes it’s orientation to the sun.