Domestic hot water heating with direct electricity from PV panels and the grid

A solar domestic hot water tank with direct electrical heating is investigated experimentally. The investigations are carried out from January to June 2024 under Danish weather conditions. The tank has five electrical heating foils on the outside vertical tank surface. The tank is well insulated, and thermal bridges are avoided by having all the pipe connections at the bottom. The different electrical foils are supplied with electricity from PV panels or the grid. A semi-smart controller allows the tank to be heated with electricity from the grid at night to establish the energy needed to cover the demand the following day. The investigations show that the domestic hot water system can supply all the energy needed for domestic hot water at a levelized cost of heat of 0.28 €/kWh. The levelized cost of heat can be directly compared to the electricity price users pay for purchasing electricity from the grid.