Measuring Primary Lens Efficiency: A Proposal for Standardization

This article describes the procedure proposed by IES-UPM to measure the optical efficiency and the irradiance of the focused spot of a primary optic for concentrator PV (CPV). The method using a broadband source (solar simulator) with a solar cell as the sensor and analysis of the focused spot recorded by a camera is described in detail here to convey the details of the optical characterization in the emerging IEC 62989 technical specification. Special emphasis is placed in noting the main sources of error and the accuracy of the measurement method. As an example, the main outcomes attained in the characterization of a set of Fresnel lenses are reported.