Testing of a small-scale stand-alone power system based on solar energy and hydrogen

Abstract

Abstract An experimental small-scale stand-alone power system based on hydrogen and solar energy has been tested. The system performance and operational experience are reported. Future expansion of the test-facility is taken into consideration using solutions with wide working ranges. The test-facility is designed for testing of individual components, for subsystems, and for complete power system operation. The complete power system in this study consists of a 4.8 kW programmable power supply, 1.5 kW electrolyser, a hydrogen purification unit (99.999% H2 quality), a 14 Nm3 H2 metal hydride storage, a 0.5 kW fuel cell, a 300 Ah lead-acid battery, and a 0.6 kW programmable load. Possible applications for such small-scale power systems are mountain cabins, remote islands, and telecommunication stations, among others. The basic idea in this particular power system configuration was to make it as simple as possible; the fuel cell and the metal hydride unit were air-cooled, and the components were connected in parallel without DC/DC converters. The only control action possible in the power system (presented in this study) was to switch the components either ON or OFF. However, connecting the components electrically in parallel without DC/DC converters gives no degrees of freedom regarding the ability to regulate power and voltage levels of the different components. Air-cooled metal hydrides might fail to deliver hydrogen due to poor heat transfer.