Power supply apparatus and method

An electrical power supply apparatus for a building 10 comprises electricity generator 26 supplying appliances at the building and an electrical energy store 30 storing energy generated by the electricity generator. A charger 32 charges an electric vehicle battery using energy from an electricity supply grid when charger criteria are satisfied, using energy from the electricity generator when operational criteria are satisfied, and using energy from the energy store when energy store criteria are satisfied. The charger charges the electric vehicle battery with energy from the energy store at the same time as using energy from the electricity generator or the grid, to provide a boost charge current. A heat transfer system and heat exchanger 24 may cool the electricity generator and provide heat energy to a building heating system. The charger may supply electricity to the appliances and to the supply grid from the electric vehicle battery when battery discharge criteria are satisfied. The energy store may be an electrochemical energy store and may store energy from the supply grid. The electricity generator and the energy store may supply energy to the supply grid. A corresponding method is also claimed.