The Stiebel Eltron Accelera 300 Heat Pump Water Heater can extract up to 80% of its energy requirements from the energy in the air around it. Compressor and fan consume only one kilowatt-hour (kWh) of electricity to generate the heat equivalent of 3 kWh to 5 kWh. Among heat pump water heaters, the Accelera 300 has the largest capacity (80 gal), highest energy factor (2.51), lowest power input (2.2 kW), and lowest power consumption (1739 kWh/year) as determined by DOE testing. The low-power consumption (500 W heat pump only, 2200 W including back-up element) makes the Accelera 300 a viable option for connecting to a PV system. The Accelera 300 is Energy Star certified, and eligible for any available tax credits or rebate incentives. There is also a 10-year warranty.