Harvesting sunlight with semiconductor-based solar cells is without a doubt one of the most important technologies to tackle energy generation as an alternative to or in the absence of fossil fuels. As such, energy-conversion devices such as photovoltaics are critical for generating electricity both to achieve the energy transition on earth as well as for space applications. While electromagnetic radiation from the sun constitutes the major source of convertible radiative energy, other types of radiation can potentially be harvested as well. This includes proton radiation from the sun, radiation from nuclear waste or other types of ionizing radiation. Likewise, conventional solar cells can be substituted or supplemented by alternative energy conversion devices like organic or perovskite solar cells, betavoltaic cells or other advanced materials that interact with ionizing radiation in a predictable and usable way.