EQUINOX: learning from developing and trialling the capability to procure flexibility from a portfolio of domestic heat pumps

This paper summarises key learnings from the second heat pump flexibility trial held by the Equitable Novel Flexibility Exchange (EQUINOX) project, which enrolled over 1,000 UK households to participate during winter 2023-4. It provides an overview of the design and results of EQUINOX trial two, which were included in full within the main trial two report [1]. EQUINOX aims to assess whether flexibility from domestic heat pumps can mitigate their impact on the distribution network, as peak heating demand typically overlaps with peak electricity demand—potentially triggering costly network reinforcement. EQUINOX has demonstrated that domestic heat pump flexibility can help to mitigate this challenge. Across 36 two-hour flexibility ‘events’ organised between 4-8pm over the winter of 2023-4, on average 47% of trial participants regularly provided turndown on request, each achieving 0.61kW of demand response (DR) for an aggregated 6.5MWh of DR over the trial. Network analysis found that if heat pump homes provide DR in line with trial two’s results, they could address 19% of the forecasted capacity exceedance at a constrained distribution network zone. Heat pumps are well placed to provide “baseload” advance dispatch flexibility that, when combined with other assets, can help alleviate capacity constraints and defer network reinforcement. The third trial in 2024-5 will consider the potential for heat pump homes to provide simultaneous flexibility to distribution and transmission networks.