Abstract
The efficiency enhancement of photovoltaic (PV) is one of the most important issues in solar cells. This research proposed an optical design, polymer micro-lens array (MLA) with high transmission, to enhance the optical absorption of PV. MLA decreases the reflection of light at oblique angles and increases the second reflection at the interface between MLA and PV. MLA will enhance the efficiency of PV at any oblique angle. The surface profile of MLA was designed and metal mold was fabricated using bulk micro-machining followed by electroplating. A high transmission polymer was spun on the metal mold to replicate a MLA thin film. Finally, thin film MLA was attached on PV surface. The efficiency of PV with MLA film at any incident angle was measured to be better than that without MLA film. The enhancement is more significant at lager oblique angle. Neglect the diffuse irradiation, annual energy of sunny day was estimated to increase from 7.78kW-hr to 7.92kW-hr, i.e. a 1.8% increase. The annual energy of cloudy day was estimated to have a 2.3% increase, from 2.83kW-hr to 2.90kW-hr. It shows that the higher potential of MLA reeals on a cloudy ady. Considering the diffuse irradiation on actual case, out door situation, an increase rate will be higher than the above numbers can be expected.