On October 31, Danish households and companies for the first time delivered ancillary services to the national power grid through the Swedish energy services company CheckWatt, contributing to a more stable, efficient, and renewable energy system.

The batteries are delivering so-called ancillary services to the national grid operator Energinet. Ancillary services are vital grid support. They rapidly adjust the flow of electricity, adding power when needed or reducing it when there is too much, to keep the electrical system stable. This prevents disturbances, while allowing for more cheap wind and solar power in the energy system, as batteries can quickly compensate for changes in their variable output.

Through pooling — or “aggregation” — CheckWatt connects many individual battery systems into a virtual power plant. This enables smaller assets that would otherwise be unable to participate in these markets to help balance the grid and generate additional income from their battery investments.

“Batteries are becoming a significant asset for the energy systems of Denmark and Europe, and Danish households and companies can now directly participate in supporting the system. Batteries offer valuable flexibility that helps manage power grid costs while simultaneously facilitating society’s transition to renewable energy sources,” says CheckWatt CEO Dan-Eric Archer.

In addition to providing grid services, batteries also create value for their owners by helping to reduce their own energy costs, for example by charging when electricity and grid prices are low or when solar panels generate surplus electricity, in order to use that electricity when prices are higher.

Besides ancillary services, CheckWatt also sees a growing market for local flexibility, where local grid operators buy flexibility to relieve the grid when it is most constrained. This is a fast and cheap way to decrease the need for costly grid expansion.