Next Generation Radiation Hard IMM Space Solar Cells

High efficiency space solar cells based on the GaInP 2 /InGaAs/Ge triple junction lattice matched device with 1 sun, AM0 efficiencies of approximately 30% are commercially available from several companies. Multiple approaches have been suggested for significantly surpassing the 30% efficiency level, but achieving this in a commercially viable cell has not been easy. We review those approaches, pointing out the advantages and challenges of each. SolAero has been focused on developing the inverted metamorphic multi-junction (IMM) solar cell, and has recently demonstrated a radiation hard version. We present the most recent performance data, including the response to particle radiation. The IMM cell can be used in a number of rigid or flexible configurations, and considerable effort has been focused on cell packaging and panel integration. The IMM device is ready to start qualification to the ECSS and AIAA standards.