striking contrast to the data of similar tests performed on zns coated silicon pv cells in the latter case the zns coating was damaged or destroyed and pv cells efficiency decreased by 30 a longer term stability study was conducted for the dlc coated si samples in a stringent damp heat test 85 u00b0 c 85 rh which is being used to qualify thin film modules by the pv industry for 762 hours results from the reflectance measurements indicate that the dlc on si thin films show negligible or no change additionally both microhardness and reflectivity did not change after heating at 350 u00b0 c for 2 hours a slight change in reflectivity but not in microhardness was observed if heated at 380 u00b0 c for 2 hours intense oxidative degradation of the films was observed however when heated to 410 u00b0 c or higher for less than 1 hour it was found that uv proton and electron irradiation do not affect the properties of dlc films and dlc encapsulated pv cells for uv irradiation tests a high pressure xenon lamp was used with the spectra similar to that of the sun but with higher intensity of uv silicon pv cells with various coatings dlc zns sio 2 were exposed to the light of the xe lamp with a uv power density of u02dc 0 5 w u00b7 cm u2212 2 for u02dc 400 hours no effects on the dlc coated pv cell efficiency were found on the other hand for a zns coated cell a u02dc 15.