Economic assessment and grid impact of different sharing keys in collective self-consumption

Collective self-consumption (CSC) is a way to increase the profitability of distributed renewable energy. In CSC schemes, a sharing key is used to virtually distribute the renewable energy production. This key impacts the cost reduction for each household, and if households are flexible, it will also impact the physical grid exchange. The aim of this article is to investigate how the new CSC scheme in Norway impacts the cost reduction for energy community members and the physical exchange with the grid, by investigating equal and yearly consumption-based sharing keys. We find that the largest cost reductions are obtained for the yearly consumption-based key, especially when households are flexible. Flexibility, however, increases the maximum import at the point of common coupling by 9.6%, due to each household individually optimising against spot price variations. Comparing the grid impact and grid related costs in the different cases, we conclude that the CSC scheme is likely to shift costs over to other end-users in the grid.