The Naval Postgraduate School offers a Back-surface, Alternating Contacts (BAC) solar cell featuring p-or-n type GaAs with alternating p-n junction regions on the back-surface of the cell, producing an improved, lighter-weight solar cell. The layers of p-or-n type GaAs are interfaced together to collect charge carriers, and a thin layer of AlGaAs is applied to the front and back surfaces to prevent recombination of charge carriers. Layer properties (thickness, material, doping, etc.) are optimized to improve overall conversion efficiency. The performance of the BAC solar cell is significantly improved by the arrangement of a GaAs-based emitter layer, heterojunction layer, and emitter-contact layer to facilitate a conduction band and valance band arrangement at layer interfaces that leads to dramatic improvements in BAC solar cell performance. Additionally, due to the very thin absorption layer, minority carriers have a much higher probability of reaching the electrical contacts and contributing to load current. The highly-reflective, back-surface, metal contacts improve solar cell efficiency by reflecting transiting or emitted photons back into the absorption layer. Additionally, a window layer and anti-reflective coating minimizes the escape cone at the front of the solar cell, effectively trapping photons and increasing the probability that they will create an electron-hole pair. These attributes provide better long-term performance in high-radiation environments; higher conversion efficiency at elevated temperatures; and a lighter, more flexible structure for mobile applications.