Abstract: Uninterruptible power supplies, solar power kits for uninterruptible power supplies and related methods are described. According to one aspect, an uninterruptible power supply includes a power bus, mains circuitry configured to rectify electrical energy received from a mains supply system into rectified electrical energy and to provide the rectified electrical energy to a power bus of the uninterruptible power supply, photovoltaic circuitry configured to convert solar energy into converted electrical energy and to provide the converted electrical energy to the power bus, a battery system configured to receive electrical energy from the power bus to charge a battery of the battery system and to discharge electrical energy to the power bus, an inverter configured to provide electrical energy from the power bus to the load, and a controller configured to monitor the photovoltaic circuitry and to implement at least one operation of the uninterruptible power supply using the monitoring.