Centrica is to absorb thousands of residential hot water tanks into its virtual power plant (VPP) to provide flexibility to the grid.

The energy giant has secured approval from National Grid to use the tanks for firm frequency response (FFR) as part of a 2.5GW VPP it is establishing in the UK.

The tanks will be provided through a partnership with Mixergy, a spin-off company from the University of Oxford which has previously received investment from Centrica Innovations.

The first batch of 100 tanks have already been installed and will be capable of storing energy at times of high renewables, responding at times of stress whilst maintaining efficiency, cost and comfort.

The tanks are set to help balance the grid through storing excess load on the grid and time-shifting demand.

Charles Cameron, chairman of Centrica Innovations, said: “The first batch of 100 hot water tanks, which are now in homes in the UK will, at times of stress, be capable of capturing energy at low market prices on sunny or windy days when there is an abundance of renewables on the network, all whilst maintaining efficiency, cost and comfort for our customers.

It is the first instance of a pool of residential devices being aggregated into a VPP comprising of larger individual industrial assets and used to deliver services to automatically balance the system, Centrica said.

The tanks are also set to reduce heat losses, water and energy usage by up to 40% a year, through a combination of sensory and Internet of Things (IoT) technologies. The hot water levels in the tank are monitored and the household usage habits learned in order to personalise water volumes and heat only what is needed.

Pete Armstrong of Mixergy said the firm is “very excited to be at the heart of Centrica’s mission” to add additional flexibility to the energy system.

“Together with Centrica, we are paving the way for smart tariffs which will reduce energy consumption and carbon emissions by storing excess renewable energy on the grid,” Armstrong added.

The use of the tanks for FFR has similarities to a trial conducted by Tesco and the University of Lincoln, whereby fridges provided the grid with frequency response services.

Centrica Business Solutions is working with a variety of global residential appliance manufacturers to explore opportunities for providing flexibility services using its demand response technology platform, Flexpond.

In June, Centrica announced its partnership with the Tokyo Electric Power Company for the use of Flexpond in providing demand response services for Japan’s grid.