Solar Panels vs Heat Pump: Which Should You Get First?

Both solar panels and heat pumps are key technologies for decarbonising UK homes. If you can only afford one right now, which should you install first? The answer depends on your current heating system, insulation, and electricity usage.

The Cost Comparison

*Heat pump savings compared to gas; can be negative if replacing a modern efficient gas boiler at current gas prices.

The Boiler Upgrade Scheme (BUS) grant of £7,500 dramatically improves heat pump economics, reducing the effective cost to £3,000–£8,000. This changes the calculation significantly.

When to Choose Solar First

Your Gas Boiler Is Still Working

If your boiler is under 10 years old and functioning well, there's no urgency to replace it. Solar panels start saving money from day one with no disruption to your heating.

You Want the Simplest Installation

Solar installation takes 1–2 days with minimal disruption. A heat pump installation can take 3–5 days and may require new radiators, pipework changes, and a hot water cylinder.

Your Electricity Usage Is High

If you already use significant electricity (working from home, EV charging, electric cooking), solar panels offset expensive grid electricity at 26p/kWh. The savings are immediate and predictable.

Your Home Isn't Well Insulated

Heat pumps work best in well-insulated homes with large radiators or underfloor heating. If your home has poor insulation, the heat pump will struggle and run inefficiently. Solar works regardless of insulation level.

When to Choose a Heat Pump First

Your Boiler Needs Replacing

If your gas boiler is failing or due for replacement, a heat pump replaces it entirely. You'd be spending money on a new heating system anyway — the incremental cost of a heat pump (after the BUS grant) over a new gas boiler can be as little as £1,000–£3,000.

You're Off the Gas Grid

Homes using oil, LPG, or electric heating have much higher heating costs. A heat pump offers dramatic savings compared to these fuels — often £800–£1,500/year. The payback is much faster than for homes switching from mains gas.

Your Home Is Already Well-Insulated

A modern, well-insulated home with decent-sized radiators or underfloor heating is ideal for a heat pump. The efficiency (COP of 3–4) means you get 3–4 kWh of heat for every 1 kWh of electricity.

You Can Get the BUS Grant

The £7,500 BUS grant makes heat pumps far more affordable. If you're eligible and your home is suitable, the grant-subsidised heat pump may offer better value than unsubsidised solar.

The Ideal Order of Investment

For most UK homes, the optimal sequence is:

1. Insulation first — loft, cavity walls, draught-proofing (£500–£3,000)
2. Solar panels second — start generating savings immediately (£6,000–£8,000)
3. Heat pump third — when your boiler needs replacing (£3,000–£8,000 after BUS grant)
4. Battery storage fourth — to optimise the solar + heat pump combination

This sequence works because each step improves the economics of the next. Insulation reduces the heat pump's workload. Solar reduces the electricity cost of running the heat pump. A battery lets you run the heat pump on stored solar electricity.

The Combined Case

When you have both solar and a heat pump, the synergy is powerful:

• Summer: Solar generates surplus electricity. The heat pump uses a fraction of this for hot water. Export the rest.
• Winter: Solar generation is lower but the heat pump's electricity demand is highest. Solar offsets some of this demand, reducing bills.
• With a battery: Store daytime solar, run the heat pump in the evening on stored electricity instead of expensive grid power.

A 4kW solar system + 8kW heat pump + 5kWh battery in a well-insulated 3-bed semi could achieve annual energy costs of just £300–£600 — compared to £1,500–£2,000 for gas heating + grid electricity alone.

Solar iBoost+ Immersion Heater Controller

£150

max power w

3000

modes

auto_divert,manual_boost

outputs

1

buddy unit available

true

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EPC Impact Comparison

Both technologies significantly improve your EPC:

A heat pump typically has a bigger EPC impact than solar because heating is a larger component of the SAP calculation. But solar's improvement is still substantial, especially when combined.

myenergi Eddi Solar Diverter

£185

max power w

3000

modes

power_divert,timed_boost

outputs

2

priority

configurable

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What the Installers Won't Tell You

Heat Pump Disruption Is Real

A heat pump installation often requires new pipework, a hot water cylinder (if you don't have one), potentially larger radiators, and external space for the outdoor unit. This can be disruptive and expensive beyond the unit itself. Solar installation is comparatively simple.

Heat Pump Running Costs Can Be Higher Than Gas

At current UK energy prices (gas ~7p/kWh, electricity ~26p/kWh), a heat pump with a COP of 3 produces heat at ~8.7p/kWh — slightly more than gas. The heat pump saves money overall because it's more efficient, but the margin is thinner than marketing materials suggest when compared to a modern condensing gas boiler.

Solar Savings Are More Predictable

Solar generation varies by weather but is reasonably predictable year to year. Heat pump performance depends on how well the system was designed, installed, and set up — there's more variability in outcomes.

The Decision Framework

For details on running solar and a heat pump together, see our solar + heat pump combination guide.

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