An exploration of load-shifting potential in real in-situ heat-pump/gas-boiler hybrid systems

Abstract

Monitoring data from two hybrid air-source heat-pump/gas-boiler systems were used to explore the systems’ potential for energy flexibility, i.e. the potential for shifting electrical load in response to grid requirements while maintaining acceptable performance in the overall hybrid system. In both cases, a significant proportion of the heat-pump load could potentially be shifted to the gas boiler with only a modest increase in the overall energy consumption, provided certain operational conditions were met. Furthermore, under these operational conditions, it is possible to estimate this additional energy consumption for a given system from simple heat output, and gas and electricity consumption data. This provides a potential basis for groups of similar systems equipped with smart technology to offer flexibility to the grid, while minimising the resulting energy penalty by choosing to use the most appropriate systems at any given time with respect to their operating conditions at that time. In addition, this type of flexibility means that the thermal comfort within the dwelling remains unaffected since overall heating requirement is met at all times by one of the two heating sub-systems.

Practical application : The ability to shift or shed electrical load in response to grid requirements is likely to become a significant, commercially incentivised aspect of building energy systems in the future, to mitigate the stress on electrical grids at times of peak consumption. For domestic systems, aggregation will be a key factor, requiring ‘smart’ systems to provide real-time information to potential aggregators or grid operators. This article explores what type of system information may be necessary in the case of hybrid heat-pump/gas-boiler systems if loads are to be shifted from the heat-pump to the gas-boiler element, while minimising the resulting energy penalties.