Should I get solar panels and a battery with my heat pump?

The combination is not a way to leave the grid. Solar generation peaks in summer, while a heat pump is needed most in winter, so in winter the heat pump is likely to be mostly powered by imported electricity³. What solar and storage change is the share of that electricity a household buys, and when it buys it.

What each part contributes: panels, battery and heat pump together

Each element does a different job, and the value comes from how they overlap. Solar panels generate electricity that can help power a heat pump⁷, and where a household already has them, using the free energy they generate to power the heat pump saves more⁸. The Energy Saving Trust estimate cited in consumer guidance is that solar cells can provide 40% of a home's energy, especially when used alongside a solar battery⁴.

The battery's role is timing. Combining solar panels with a home battery lets a household store free, renewable electricity to power the heat pump, making it less reliant on grid electricity⁹. A solar battery can increase savings further by storing the sun's energy to power the heat pump later in the day⁸. Official guidance goes further: installing solar PV and battery storage alongside a heat pump can significantly lower bills in all cases⁶.

The heat pump itself is the largest new electrical load in most of these homes, and it is a steady one. A heat pump uses roughly the same amount of electricity every hour of the day if it is set up to deliver steady warmth¹⁰. That steadiness is what makes a battery useful: there is a predictable demand to cover, rather than a spiky one.

There is a second, separate option in the same family. A solar assisted heat pump heats water by absorbing heat from direct sunlight and from the air, and can work without direct sunlight¹¹. The amount it saves on fuel bills depends on how much hot water is used and what system currently heats it¹¹. That is a different product from a standard air source or ground source heat pump with solar PV, and it is covered further below.

Running the heat pump at night and during peak rates from a battery

The mismatch between when solar generates and when heating is needed is the central practical problem. Solar PV produces most in summer while the heat pump is needed most in winter, so the heat pump is likely to be mostly powered by imported electricity in winter³. A battery cannot close a seasonal gap; it closes an hourly one.

That hourly role is real. A heat pump uses roughly the same amount of electricity every hour of the day when set up for steady warmth¹⁰, so a battery charged during the day or on a cheap overnight rate can cover the expensive evening period. Independent guidance on tariffs points to a heat pump tariff that includes a peak rate, using the battery to power the heat pump during expensive periods¹². The same guidance notes that where a good export tariff is not available from a supplier with a good import tariff, a solar panel and battery tariff may suit, especially with a larger than average solar system or a smaller than average heat pump¹².

Standard operating advice cuts across this. Guidance on running a heat pump efficiently is to avoid heating hot water or the house overnight when outside air temperatures are significantly lower, unless the household is on a time of use tariff⁹. A battery changes the economics of overnight running without changing the physics: the heat pump still works harder in colder air.

Some hybrid systems automate the decision. Controls on some hybrid heat pumps choose when and how the heat pump runs based on electricity costs, fossil fuel supply costs, time of day, and whether solar panels are generating or exporting¹³. A heat battery trial took a different route, charging renewable heat into large capacity time-shifting thermal storage that delivers space heating and hot water on demand¹⁴.

Solar thermal panels alongside a heat pump: a different option

Solar thermal collectors are not the same product as solar PV, and they interact with a heat pump differently. Solar thermal panels can be installed alongside other renewable or traditional heating systems, though they are not so easy to combine with a combi boiler¹⁶. Coupling a solar collector with a heat pump is an established system design¹⁷.

The official position on the heat pump side is permissive. Guidance states that ground source heat pumps can be used to augment existing heating systems in the same way as solar panels¹⁸, and the same wording applies to water source heat pumps¹⁹. That describes heat pumps augmenting a system, not solar thermal feeding a heat pump, and the two should not be conflated.

A third route combines both functions in one panel. Hybrid PV-T panels combine photovoltaic cells with solar thermal panels, so that the same panel can generate heat and electricity⁵. For a household with limited roof area, that is the only way to get both outputs from one mounting.

On the electrical side, solar panels can also power a dry electric underfloor heating system, and a battery to store excess solar electricity would make this more efficient²⁰. Heat pumps themselves can work with radiators or underfloor heating, though some types can work without either⁷.

Sizing and compatibility: what your system needs to support

Sizing rules for the heat pump are set by building regulations, and they are strict. A primary heating system containing heat pumps should be selected to meet the full space heating requirement at the design condition chosen for heat loss calculations, and it should not be assumed that any heat will be supplied by additional secondary heaters²¹. The earlier English approved document uses the same principle: heat pumps should be selected to meet the full space heating requirement at the design condition chosen for heat loss calculations²². Approved Document L also states that heat pump systems have been sized appropriately²³.

Grant schemes apply their own tests. Heat pumps that integrate with solar photovoltaic systems are eligible under the Boiler Upgrade Scheme²⁴. Under the Warm Homes: Local Grant, the heat pump is sized to provide a minimum of 55% of the calculated heat load for retrofit and packaged hybrids²⁵. Older scheme guidance required the heat pump or biomass boiler to provide both space and hot water heating and to be capable of meeting the full space heating and hot water heating demands of the property²⁶.

On the solar side, there is no agreed minimum array for a heat pump. Powering a 7kW heat pump in addition to a home's other demand needs a large array³. An average domestic system is around 4kWp, which requires at least 20 square metres of roof space⁵. Guidance on the minimum system size for a heat pump is not settled: figures of at least 5kW and at least 5.6kW are both in circulation.

In Northern Ireland the connection process is separate. Installing solar panels or wind turbines, or adding a new battery, is a different process from the heat pump and EV charger connection route²⁷.

What the combination means for household energy independence

The combination moves a home part of the way towards self-sufficiency, and the remaining dependence is worth stating plainly. A heat pump uses electricity, and in winter most of that electricity is likely to be imported³. The grid connection, and a supplier, remain. What solar and a battery change is the volume and timing of imports, not their existence.

The direction of travel in UK housing is towards this combination. A documented case study household installed an air source heat pump with radiators, a 3kWp solar PV array and a 10kWh battery²⁸. A monitored integrated electric home runs an air source heat pump, solar panels and a battery together²⁹. Guidance on the energy efficient house of the future lists solar panels, a heat pump, battery storage, underfloor heating and larger radiators, an EV charger, full insulation, double or triple glazing, a high standard of draught-proofing, a ventilation system and smart heating controls³⁰.

There is a tax treatment point that reflects how these parts are treated as one installation. Official guidance describes solar panels and batteries that stored power produced by the solar panels forming a single supply of the installation of energy-saving materials in residential accommodation³¹.

The dependence that remains is not only the grid. It is also the tariff, the supplier and the control system. A battery only earns its keep against a tariff structure that rewards shifting load, and the guidance on which tariff suits depends on the relative size of the array and the heat pump¹². For a household weighing the decision, the honest summary is that solar and a battery reduce how much energy is bought and when it is bought, while the heat pump keeps the home on the electricity system.