Among heat pump water heaters, the Stiebel Eltron Accelera 300 has the largest capacity (80 gal.), highest energy factor (2.51), lowest power input (2.2 kW) and lowest power consumption (1,739 kWh/hr.) as determined by U.S. Department of Energy testing. The low-power consumption (500-watt heat pump only; 2,200-watt including backup element) makes the Accelera 300 a viable option for connecting to a photovoltaic system. The Accelera 300 is Energy Star-certified and eligible for any available state or local tax credits or rebate incentives. It carries a 10-year warranty.

Stiebel Eltron.