Nyhet | 2016-09-26 | 13:11

Optimization of a household battery storage – the value of load shift

Thesis (30 hp) by Christoffer Boström at Uppsala University.

Supervisors at Vattenfall: Elin Dahlborg and Tobias Rehnholm.

Summary

Sweden’s energy system is facing major changes in the near future in order to reduce carbon emissions and to switch to sustainable energy sources. PV systems have become a sensible alternative for homeowners that want to be a part of this change and at the same time reduce the cost of their electricity bill. To further improve the utilization of their PV system and to handle the intermittent nature of solar power, battery storages have become an interesting system complement.

This thesis investigates how batteries can provide smart services; load shift and peak price energy utilization to a household. This is done by developing an optimized battery algorithm model that can provide these smart services which is compared to a simple battery algorithm. The results show that the developed battery optimization model works as intended. It performs both load shift and peak price energy utilization. The economic analysis shows that the most profitable PV system and battery configuration is a 20 kW PV system with a 5 kWh battery. The system has an internal rate of return, IRR, of 2.3% which does not reach Vattenfall’s weighted average cost of capital, WACC, at 7%.

The results also show that the battery cost is an important factor for a system's profitability. A larger battery system is more expensive and the increased yield does not cover the increased cost. Further research is needed to implement the optimized battery as a functional application since the model has access to a perfect forecast and thus a method for forecasting PV production and load profile of the household are crucial to get similar results.