Micro-Concentrator Photovoltaics for Deep Space Missions: Overcoming LILT Challenges with High-Specific-Power Solar Arrays

Exploration of the outer solar system is one of the European Space Agency (ESA) top scientific priorities, as defined in the Voyage 2050 program. Micro-concentrator photovoltaics (micro-CPV) are gaining attention as a viable approach to power spacecrafts operating in deep space, where conventional solar arrays may suffer severe drops in performance due to low-intensity, low-temperature (LILT) conditions. This study reports on the design, development, and testing of two novel micro-CPV solar panel architectures optimized for maximizing specific power beyond Mars orbit and for being compatible with the standard 5° angular accuracy of spacecraft attitude control: first, a silicone-on-glass (SoG) Fresnel microlens array and, second, a catadioptric concentrator that combines refraction with total internal reflection (TIR). Optical simulations indicate that the Fresnel concept delivers higher efficiency and lower mass, while the catadioptric design offers superior angular tolerance and alignment stability. Initial Fresnel prototypes were fabricated and characterized, achieving 83–85% optical efficiency, +/-5° acceptance angle, +/-1.5 mm focal distance tolerance and excellent uniformity across the 72 lenses in the array. These findings confirm both the feasibility and manufacturability of micro-CPV technology, which is expected to surpass the specific power of conventional cell-interconnected-cover (CIC) arrays for the next large scientific missions of ESA to the outer solar system.