The energy-saving Tempra Plus is a tankless electric water heaters and the Accelera 300 is a heat pump water heater. Tempra Plus tankless electric water heaters feature advanced flow control to automatically keep output temperature constant and provide an unlimited stream of hot water. Units are ideal backups for solar thermal systems. Accelera 300 heat pump water heaters have a large capacity (80 gal), low power input (500 watts in heat pump mode; 2.2 kW including back-up element), and low power consumption (1,391 kWh/year).