Advanced Cooling Technologies, Inc. (ACT) proposes to develop a TRAP (Thermo-Radiative Assisted Photovoltaic) Cell technology to simultaneously harvest the incoming solar and outgoing thermal radiation in a single integrated device, with goals to achieve total efficiency >35% in the near-term (~2 years) and > 45% in the mid- to far-term (5-10 years). ACT’s TRAP Cell leverages the “dark” photovoltaic (i.e., thermo-radiative (TR) cell) technology that ACT has developed in two previous successful NASA SBIR programs. A TR cell can be viewed as the reverse mode of a PV cell. In a PV cell, the electrical power generation can be viewed as a result of the imbalance of incoming radiation from the sun and outgoing radiation from the PV cell. Conversely, the electrical power generation in the TR cell is a result of imbalance of the outgoing thermal radiation and negligible incoming radiation (from deep space), which creates a charge carrier motion resulting in electric power generation. Our proposed TRAP Cell will consist of three layers: a conventional space photovoltaic cell as the top layer, a mid-infrared transparent solar absorber as the middle layer, and a “dark” photovoltaic cell as the bottom layer. When producing electrical power, the conventional PV cell needs to face the sun, while the “dark” photovoltaic cell needs to face the ultra-cold deep space. To address the challenges when combining them together, we introduce a mid-infrared transparent solar absorber layer (e.g., undoped germanium layer) between the solar cell and the “dark” photovoltaic cell. Due to the mid-infrared transparent nature of the solar cell (top layer) and solar absorber (middle layer), the bottom thermo-radiative cell layer is only radiatively coupled to the ultra-cold deep space, while the top and middle layers will utilize the entire solar spectrum by either generating electricity directly or converting unused solar radiation into heat to provide thermal energy for the bottom layer
One application is to produce more electrical power during the lunar day due to the enhanced system efficiency, while also continuously generate electrical power by the thermo-radiative cell part using the waste heat during the lunar night. This enhances and extends the performance for lunar missions. Another potential application is attaching TR cells to the radiators of RPS to significantly increase the electrical power output and boost the overall system efficiency of many deep space missions
Our TRAP Cell technology could be used as the residential solar panels in the future. In the daytime, the panel could produce much more electrical power than that produced by conventional solar panel alone. In the nighttime, the bottom TR cell layer can still produce electrical power. Therefore, our system could continuously generate electricity for residential use throughout the day and night