A report discusses the development of a Mars surface, laboratory-based solar simulator to create solar cells that can function better on Mars. The Mars Optimized Solar cell Technology (MOST) required defining the surface incident spectrum, developing an appropriate laboratory solar simulator measurement capability, and developing and testing commercial cells modified for the Mars surface spectrum.
Based on analysis and measurements of the Mars surface spectrum, a standard spectrum has been developed for testing by modifying the output spectrum of standard xenon commercial space solar simulators with light filtered to reproduce a Mars surface spectral distribution suitable for measuring existing solar cells. An external filter wheel has been fabricated that holds a number of filter elements. The appropriate filters are determined by analysis and filter availability, and are tested to verify the spectrum for solar-cell testing. The filter assembly is adjustable to changes in the simulator output due to specific light bulbs or bulb aging.
Prior to the advent of the MOST program, the estimated Mars surface solar array performance was based on its AM0 output at the distance of Mars, modified by a factor to account for the atmosphere. With the continuing success of the Mars exploration rovers (MERs), it is clear that the use of multijunction photovoltaics on the surface is a realistic option for high-power, long-life operation. The MOST program has resulted in development of a solar simulator that can provide the appropriate spectrum of sunlight on the Martian surface. The MOST program is in the process of demonstrating that AM0-optimized high efficiency solar cells can be tailored to operate more optimally under Mars surface conditions, and to generate higher power and predictability over a range of conditions.