Solar Panels vs Heat Pump
Solar Panels vs Heat Pump: Which Should You Install First?
This is one of the most common questions people ask when they're trying to decarbonise their home — and it's a good one, because the order actually matters. Both are excellent investments. But if you can only do one right now, here's how to think about it.
Short answer: it depends on your boiler. If your boiler needs replacing soon, do the heat pump first. If your boiler has years left in it, do solar first. And if you can do both together, that's the sweet spot.
The Numbers
| Feature | Solar Panels | Heat Pump |
|---|---|---|
| Upfront cost | £5,000–£7,000 (4–5kWp system) | £8,000–£14,000 |
| Grant available | None (but 0% VAT) | £7,500 BUS grant |
| Net cost after grant | £5,000–£7,000 | £500–£6,500 |
| Annual savings | £1,000–£1,800 | £200–£400 vs gas (more vs oil) |
| Payback period | 4–6 years | 8–15 years |
| Disruption to install | 1–2 days, minimal | 2–5 days, potentially significant |
| Maintenance | Very low | Annual service |
| Lifespan | 25–30 years | 20 years |
Solar Has the Better ROI
On pure financial terms, solar panels win. The payback period of 4–6 years is hard to beat for any home improvement. You put in £5,000–£7,000 and you're saving £1,000–£1,800 every year for 25+ years. That's a genuinely excellent return.
The savings come from two places: electricity you don't have to buy from the grid, and payments from the Smart Export Guarantee (SEG) for excess power you export. With electricity prices staying high, those savings are substantial.
A heat pump does save you money on heating bills — but the savings compared to gas are more modest than people expect. You're switching from gas at roughly 5–7p/kWh to electricity at 24–25p/kWh, but using 3–4 times less of it due to the heat pump's efficiency. The maths roughly works out, but it's not a dramatic saving over a modern efficient gas boiler. Over oil it's a different story — we'll get to that.
Heat Pump First If Your Boiler Is on Its Way Out
Here's the thing about heat pumps: the right time to install one is when your boiler needs replacing anyway. If you're staring down the barrel of a £2,000–£3,000 boiler replacement, that changes the calculation entirely. You're going to spend money on heating equipment regardless — you might as well spend it on something that gets you off gas permanently and qualifies for the £7,500 BUS grant.
Don't wait for your boiler to die and then scramble to install a heat pump. Heat pump installations take time to plan properly — you may need radiator upgrades, a new hot water cylinder, and a decent commissioning process. If you know your boiler is 15+ years old, start planning now.
The Combination Is the Best Answer
This is where the real magic happens. A heat pump running on solar electricity is one of the most cost-effective heating solutions available in the UK. During the day in spring, summer, and autumn, your solar panels can directly power your heat pump — meaning you're heating your home essentially for free during daylight hours.
A well-designed system with both solar and a heat pump can cut your heating and electricity bills by 70–80% compared to a gas boiler with no solar. Add a battery, and you're capturing that solar generation to use overnight too.
The ideal setup if budget allows: install the heat pump and solar together. You'll often get a better deal from an installer who does both, and the systems can be optimised to work together from day one. Some installers and energy companies will offer combined packages.
What If You Have Oil Heating?
If you're on oil, skip this comparison and go straight to a heat pump. The savings from switching off oil are much larger than from switching off gas, and there's no grant for an oil boiler replacement. The heat pump pays back much faster for oil homes. See our heat pump vs oil boiler comparison for the full breakdown.
The Verdict
- Boiler working fine? Install solar first. Better ROI, faster payback, no disruption.
- Boiler needs replacing? Install the heat pump now. Use the £7,500 grant, don't waste money on another gas boiler.
- Can you do both? Yes — do both. It's the best investment you can make in your home's energy future.
For more on the costs involved, see our heat pump costs guide and solar panel costs guide.