A system for the evaluation of solar cell samples

Abstract

The system described is a solar cell test vehicle intended primarily for education and research applications. Because of the many advantages to be derived from testing cells under real sky conditions, the sun is utilized as the system's energy source. Provisions are made for the collimation of the incident energy to simulate space conditions when desired, and also to provide a known angle of incidence when testing cells for either terrestrial or space applications. The mobile equipment console, complete with necessary instrumentation and power supplies, facilitates positioning the apparatus in an open area remote from the laboratory. The system design provides for the measurement of open circuit voltage, short circuit current, internal impedance, and output power, each as a function of incident energy. A means for the accurate angular positioning of the solar cell provides for the determination of cosine response. A specially-designed, direct read ng pyrheliometer featuring fast response provides normal incident radiation data, allowing for the accurate determination of conversion efficiency. Spectral response measurements are made by comparing the output of the cell under test, both with and without accessory band-pass filters. The temperatures of both the solar cell and the ambient air can be monitored for future data correlation. A clock drive provides for the continuous alignment of the sample holder with the sun, allowing for measurements over extended periods of time. Samples as large as 4·3 in. in diameter can be accommodated.