Application of optical film with micro-lens array on a solar concentrator

A plastic solar concentrating optical film with horizontal cylinder micro-lens array (HCMA) is presented in this study. The solar concentrator (SC) is in the form of optical film with HCMA and it is attached on the surface of a solar cell. This film is a polymethylmethacrylate (PMMA)-based optical layer. Compared with a plain solar collecting optical film without HCMA, the solar collecting optical film with HCMA can reduce the opportunity of reflection as light arrives at the surface and therefore can increase the refraction coefficient. As a result, the gain of photovoltaic power can be improved with the SC. Light is efficiently refracted by the HCMA and absorbed by the solar cell without the need of a solar tracking mechanism. Optimization of geometrical parameters of HCMA such as contact angle and gap (interspace) between each horizontal cylinder micro-lens is designed by simulation. The procedures of fabrication include reflow process, nickel-cobalt (Ni-Co) electroplating, and molding process. The measurement equipment of NEWPORT Oriel 91160+MODEL 6285 is utilized to measure the parameters such as open-circuit voltage V_oc, short-circuit current I_sc, and fill factor F.F., relating to the efficiency of the complete system. The experimental results show that a gain of photovoltaic power of about 3.30% is obtained with a contact angle of 62° and a gap of 15 μm.