Benchmark of grid connected battery systems for buildings

In this project, methods are developed and validated that enable a qualitative comparison of different network-connected battery systems for buildings.

Because of decreasing prices for solar cells and batteries, a vast increase of the number of battery systems and battery-solar hybrid-systems are expected in Danish buildings. A PV-system with battery increases the selfconsumption of energy from the sun significantly. Ener-ginet.dk estimates an increase in production capacity from solar cells to 10-double over the next 25 years to 7.5 GW, out of which about 50% of the systems will be combined systems with batteries with an estimated storage capacity of 3.5 GWh. Denmark is therefore facing a potential boom in a new, not yet regulated technology, with associated new opportunities and risks.

In this project, methods to determine key parameters is developed and validated by testing 3-5 systems. Some key parameters can be derived from data sheets, but battery lifetime, energy capacity and average system efficiency are some of the most important parameters, which are highly affected by the load pattern, standby consumption, energy losses in power electronics and battery. Standardized tests to determine comparable values for different battery systems is therefore required.