This article discusses a DIY solar panel voltage converter project that can be used to power small indoor IoT devices. The project, published in 2015, utilizes an LTC3129 integrated circuit and a CR2032 backup battery to efficiently harness energy from a low-cost mini solar panel. The circuit is designed to operate with an input source as small as 7.5 μW, making it a practical and cost-effective solution for powering indoor IoT devices with renewable energy sources.