How efficient are they?

They are very efficient when placed at a southern exposure to the sun. They should receive full sun between the hours of 10 to 3 for best efficiency, and should not be shaded. Even the shade from a small branch can lessen the efficiency. Our UNI-SOLAR panels, however have Bypass diodes connected across each cell, enabling the modules to produce power even when partially shaded.

Our UNI-SOLAR products are based on a sophisticated multi-layer amorphous silicon thin-film solar cell developed originally by Energy Conversion Devices, Inc. This spectrum-splitting cell is constructed of three separate p-i-n type, amorphous semiconductor solar sub-cells, each with a different spectral response characteristic. This allows the cell to convert the different visible and near infrared wavelengths of sunlight with optimal efficiency. The United Solar spectrum-splitting multijunction design now holds all the world's records for amorphous silicon solar cell efficiency, including the highest stable efficiency measured by the National Renewable Energy Laboratory (NREL) for a small-area amorphous silicon solar cell -- 13 percent.