Facts & figures:
Building: Two-family house with 240 square metres of living space
Residents: Five adults, one child
Year of construction: Before 1980
Living space: 240 square metres split over two homes
Photovoltaics: Self-consumption system with 17.6 kilowatt peak. East-west
Inverters: Two PLENTICOREs in a device network – known at KOSTAL as dual power for short – with 10 kW and 5.5 kW
Energy storage unit: BYD, 12.8 kilowatt hours
*KOSTAL dual power: The energy of the second PLENTICORE inverter can also be stored as AC using the "smart AC link" function. This means that all the PV generator output is available to charge the battery during transitional seasons. Nevertheless, all inverters supply the house grid. Only when the energy from the photovoltaic system is no longer sufficient does the inverter connected to the energy storage unit draw energy from this unit – and it draws exactly the amount required, so that no energy has to be drawn from the public grid. Domestic consumers such as heat pumps can be easily integrated into the KOSTAL dual power system. All the customer needs to do is install the KOSTAL Smart Energy Meter so that it can "see" (measure) the demand of all consumers – including the heat pump.
Energy management: KOSTAL Smart Energy Meter (KSEM) in combination with two PLENTICORE plus inverters
Work cascade: 1. Cover domestic consumption; 2. Charge energy storage unit; 3. Feed into the grid
Heat pump: WPL 20 A air-water heat pump from Stiebel Eltron with a rated output of 9.54 kW. The calculated annual performance factor (APF) for heating and hot water was 3.6. The value actually observed from July to December 2021 was 3.57. Panel radiators are used in the building. The residents describe the heating performance in the winter months as very good.