Research

Long term testing and evaluation of PV modules with and without Sunarc antireflective coating of the cover glass

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Abstract

Two Photovoltaic (PV) modules have been manufactured by Swemodule. One with Sunarc antireflective coated glass and one without glass surface treatment. The modules have been tested at DTU during 16 months under realistic outdoor conditions. Exactly the same polycrystalline cells were used in the modules. No cleaning of the glass has been made except for removal of bird droppings and leaves on single cells that could give a very wrong comparison. The PV modules were mounted due south at 45 degree tilt angle. They were connected to the electric grid with small 250W module inverters from Involar that also realized the MPP tracking to give the maximum output of each module. The electric power output was measured both on the AC and DC side and with different measurement equipment to be sure about the accuracy in improvement. The results indicate a potential long term improvement in a system from 3% up to 6%. The improvement is best in facade and off south tilted orientations, where the better incidence angle modifier, has a larger influence. In the PV application only one side of the glass treatment is active. This reduces the possible improvement compared to solar thermal and greenhouse applications. In PV applications the slightly higher cell temperature, due to the higher transmittance of the glass for all solar wavelengths, reduces the potential electrical performance improvement.