Thanks to funding from the Shanghai City government, Shanghai Import Export Trading Company, and Shanghai Flower Port, we have designed and fabricated in pilot production the first 3-sun 180 W (STC) mirror panels. Three of these panels were first tested in the US showing calibrated PTC ratings of 150 W. Then 24 panels were installed on two 2-axis trackers at the Flower Port in Shanghai. Then 672 panels were installed on a horizontal beam tracker on a building rooftop at the Flower Port. Test results are presented here. These systems performed as expected.
3-SUN MIRROR MODULE CONCEPT
The cost of high purity silicon feedstock today is well over $50 / kg whereas the cost of aluminum is only about $2 / kg. Crystal growth adds more cost to the silicon solar cells. Therefore, substituting aluminum mirrors for single crystal cell area can dramatically reduce the cost of a module. This reasoning leads us to the 3-sun module concept shown in figure 1.
Our concentrator module design uses existing planar cells. As shown in figure 2, we simply cut standard 125mm x 125mm SunPower A300 cells into thirds. In addition, our module design uses standard circuit lamination procedures and equipment. However, as shown in figure 3, we add a thin aluminum sheet at the back of the laminated circuit for heat spreading. While a standard planar module contains rows of 125mm x 125mm cells, our low concentration modules consist of rows of third-cells with each row now 41.7 mm wide. We then locate linear mirrors with triangular cross sections between the cell rows (figure 1). The mirror facets deflect the sun's rays down to the cell rows.
Start-up of first 100 kw system in Shanghai with 3-sun PV Mirror modules