Solar and heat pumps for business — why electrifying your heat changes the solar case

Solar and heat pumps are usually treated as two separate decisions. They shouldn't be. Electrifying your heat fundamentally changes the economics of solar — and often for the better — because it converts a chunk of your energy use from gas into exactly the kind of daytime electrical demand that solar is best at feeding. This guide explains the link, and where it holds up for a commercial building.

The connection most people miss

The thing that makes commercial solar pay is self-consumption — using your generation on site rather than exporting it cheaply (we explain why that's the whole game in our self-consumption guide). The more daytime electrical demand you have, the more of your solar you soak up at full value.

A heat pump is, from the grid's point of view, a new daytime electrical load. If you currently heat with gas and switch to a heat pump, you've moved energy demand out of the gas bill and into the electricity bill — and a large part of that new electrical demand falls in daytime hours when your panels are generating.

So the two technologies are complementary in a specific, measurable way: the heat pump creates demand; the solar supplies it cheaply. Each makes the other's business case stronger.

How a heat pump actually changes the numbers

Two effects work in your favour:

1. More self-consumption. New daytime load means a higher share of your solar is used on site at the full retail-offset value (25–35p/kWh) rather than exported at the Smart Export Guarantee rate (~8.5–15p/kWh). That can lift the return on the solar investment.
2. Cheaper heat. A heat pump delivers heat at an efficiency (its "coefficient of performance") of roughly 3–4 units of heat per unit of electricity. When that electricity is partly free solar, your effective cost of heat drops further still.

There's a counterweight to be honest about: heat demand is highest in winter, when solar generation is lowest. The seasonal mismatch means solar won't cover much of your heating in January. The pairing works best where you also have year-round daytime demand — hot water, process heat, cooling that runs in summer — so the solar has somewhere useful to go when it's not feeding the heat pump.

Where the pairing stacks up well

• Buildings with significant year-round heat or hot-water demand — hospitality, care, leisure, food and process businesses.
• Sites already running daytime cooling/AC, where summer solar feeds the cooling and winter solar offsets the heat pump's shoulder-season running.
• Premises planning a gas exit for cost, carbon-reporting or MEES/EPC reasons — doing solar and heat-pump planning together avoids two disruptive projects.
• New builds and major refurbishments, where electrifying heat from the start is far cheaper than retrofitting later, and the roof solar can be specified to match.

Where to be cautious

• Poorly insulated buildings. Heat pumps work best with lower-temperature, well-retained heat. Drop one into a leaky building expecting gas-boiler flow temperatures and you'll get poor efficiency and high bills — solar or no solar. Fabric first, then heat pump, then solar to feed it.
• Pure winter-peak heat demand with no summer load. If your only new electrical demand is January heating, the solar-to-heat-pump synergy is weak — the panels are generating least when the heat pump needs most. The solar may still pay on your other daytime loads, but don't oversell the heating link.
• Grid connection limits. Adding a heat pump and solar and perhaps EV charging can push you toward your supply capacity. A bigger electrical load may need a DNO conversation — the same connection gatekeeper that governs larger solar arrays (see planning permission and grid connection).

Think of it as one electrification plan

The smartest way to approach this is to stop seeing solar, heat pumps and EV charging as three projects and start seeing them as one electrification roadmap for the building:

• Heat pumps and EV charging add controllable daytime demand.
• Solar supplies that demand cheaply.
• A battery (sometimes) shifts surplus generation to cover the gaps — worth modelling, not assuming (see battery storage).

Designed together, they reinforce each other: every kW of new daytime load is another kW of solar you can self-consume at full value. Designed separately, you risk sizing the solar wrong, hitting a grid limit unexpectedly, or paying for two rounds of disruption.

A sensible sequence

1. Fabric first — insulation and controls, so the heat pump runs efficiently.
2. Right-size the heat pump to the improved building, not the old gas demand.
3. Pull your half-hourly data and model the combined electrical demand profile — existing load plus heat pump plus any EV charging.
4. Size the solar to that combined daytime profile, not to the roof or to today's bare consumption.
5. Check the grid connection can take the total before you commit.

Sanity-check, in one line each

1. A heat pump turns gas demand into daytime electrical demand — solar's favourite kind.
2. More daytime load means more solar self-consumed at full value.
3. Heat demand peaks in winter when solar is lowest — the link is strongest with year-round daytime load.
4. Insulate first; a heat pump in a leaky building disappoints regardless.
5. Plan solar, heat pump and EV charging as one electrification roadmap.
6. Watch your grid-connection capacity as combined load grows.

The bottom line

Electrifying your heat isn't just a heating decision — it reshapes your solar case by giving the panels somewhere valuable to send their power. Where you have year-round daytime demand and a building that's fit for a heat pump, the two technologies make each other pay harder. Plan them together, model the combined demand from real data, and size the solar to match.

To model the combined demand and savings, run the calculator and read our self-consumption guide. For the EV side of electrification, see EV charging and solar for business. For monthly plain-English guidance, subscribe to the Brief.

General information, not financial or engineering advice.