► We design a simple solar-powered water pump to supply water in developing countries. ► A linear actuator is used to provide the lifting force. ► An optimization method matches PV panel characteristics to pump hydraulics. ► Geometrical/electrical options are compared by FE analysis and analytic expressions. ► Model predictions achieved close comparison with measured results from a prototype. A need has been identified for a simply constructed, photovoltaic-powered, water pump to improve the water supply in rural areas of developing countries. The use of a linear actuator to provide the lifting force was investigated as part of a way to meet this need. Substantial challenge was presented in optimizing the system to suit the power characteristic of a photovoltaic panel and the hydraulic requirements of the application. An iterative process combining finite element analysis and analytic expressions was devised to allow comparisons to be made between many geometrical and electrical configurations of the linear actuator. Model predictions achieved close comparison with measured results from an existing water pump. The modelling technique was used to generate an actuator design that will utilize the available power more efficiently in a next generation pumping device.