A compact AAA-compatible multispectral solar simulator based on spherical cap chamber

Abstract

Rapidly developing thin-film solar cells prompts the demand for artificial narrow-band spectral illumination. Here, an LED-based compact spherical cap solar simulator is proposed to provide multiple independent color channels, while compatible with the traditional broadband IEC60904-9 standard in terms of illumination non-uniformity, stability and solar-like spectrum. Firstly, a one-dimensional model is established and then validated to analyze locations of maximum power point which may degenerate the spatial homogeneity. Secondly, the LED layout is optimized by Monte Carlo ray tracing, and it is found that a good illumination uniformity can be achieved if they are rotational symmetrically distributed. Thirdly, another two structural parameters, including output slot size and cavity height, are simulated to balance the output uniformity and output power. Finally, an instance simulator based on the structure is developed for performance verification. In the implementation, heat dissipation strategies are introduced to stabilize the system, including the use of heat sinks and flip-connected printed circuit boards to keep heat sources away from the optical chamber, thereby ensuring 0.052% short-term and 1.13% long-term stability. In addition, seven types of LEDs are adopted to simulate the solar spectrum, and its maximum deviation between the AM 1.5G is −8.82%. A control system consisting of a graphical user interface, STM32 microprocessor and constant current sources is developed to configure the current of different color channels. As a result, in predominant area of the entire output slot, six narrow-band and broadband illuminations can achieve 2% non-uniform, which is of interest for testing thin film solar cells.