Low Resistance Solar Cells for the First Spanish Concentrating Photovoltaic Array

Summary

We have developed a two-axis photovoltaic tracking array of 20.80 m² aperture equipped with monocrystalline silicon solar cells and hybrid silicone-glass Fresnel lenses, capable of yielding 1.5 KW peak under AM1 conditions. The effective concentration ratio is 55X. We have found that the use of certain two-level metallization grids reduces the series resistance and improves the performances of concentration solar cells. We have made n p silicon solar cells of 5 cm diameter with an efficiency of 16.6% at AM1 and 28°C and we measured series resistance values comprised between 40 and 200 mΩcm. These cells have been encapsulated over metal plates to achieve good thermal and electrical contacts. We measured 6°C thermal drop between the cell and the cooling element for AM1 irradiance. The maximum temperature between the cell and the ambient under the same conditions in a windless day has been 35°C.