Solar panels and heat pumps: why they are the perfect energy pair
Heat pumps raise electricity use, solar cuts the expensive part. Understand the seasonal mismatch, simple load-shifting strategies, and when a battery helps.
Solar panels and heat pumps: why they are the perfect energy pair
A heat pump changes your home’s energy maths.
Want to see what solar could look like for your area? Find your postcode.
Instead of buying most of your heating energy as gas, you buy it as electricity. That usually pushes your electricity use up a lot, which is exactly what solar likes. More demand means more opportunities to use your own generation rather than exporting it.
The catch is timing: UK solar peaks in summer, while heating demand peaks in winter. That mismatch is real, but it is not a deal-breaker. With a few simple strategies (and an optional battery), solar and heat pumps can work together extremely well.
This guide explains the trade-off in plain English, with practical sizing and usage tips.
Quick answer: why solar + heat pump works
- A heat pump typically increases the electricity you buy, often by roughly 40–60% on the meter (varies by home, insulation and previous heating).
- Solar helps most when you can use your generation directly, because import electricity is usually worth far more than export.
- Even though winter heating demand and winter solar do not align, the overlap in spring and autumn can be very valuable.
- Simple load shifting (hot water at midday, gentle pre-heat on sunny days) can lift self-use without buying anything new.
- A battery can help move solar into the evening, but it cannot “fix winter”. Treat it as an optional bridge, not a requirement.
If you want the practical next step: run your postcode through the SolarByPostcode calculator and compare outcomes with and without a battery assumption.
Assumptions and variability
- The “40–60% higher electricity use” rule of thumb is a planning shortcut. Real homes can land outside that band depending on insulation, flow temperatures, hot water demand, and how much gas you used before.
- Solar value here is driven more by when you use electricity than by any UK-average annual output. Occupant routines and controls can shift results a lot.
- Your roof and location matter. Postcode-level sunshine, roof orientation, shading, and usable roof space can change annual generation meaningfully.
- Tariffs matter. Import rates, export rates, and any time-of-use pricing can move the economics even if the panels and heat pump are identical.
- We keep examples illustrative and focus on decision logic. For how SBP estimates postcode-specific output and savings, see Data sources and methodology.
Why a heat pump changes the solar ROI story
A heat pump does not create energy. It moves heat from outside to inside, using electricity to do it.
That means:
- Your gas use drops (often dramatically).
- Your electricity use rises (sometimes a lot).
How much it rises depends on your home, your heat loss, your hot water needs, and the heat pump’s seasonal efficiency. But as a planning rule of thumb, many households find their annual electricity consumption ends up roughly 40–60% higher than before.
That matters for solar because solar economics in the UK is mostly about one thing:
How many of your generated kilowatt-hours you use yourself (self-use), instead of exporting.
More demand makes high self-use easier.
The seasonal mismatch (and where the value really is)
UK solar generation peaks in late spring and summer. Heat pump demand peaks in winter.
That sounds like a mismatch (it is), but notice what happens in the shoulders: spring and autumn often have useful solar and meaningful heating demand at the same time.
So yes, the mismatch exists. But the overlap season is big enough that it can materially improve payback, especially if you use the right control habits.
Three simple load-balancing strategies that work
You do not need fancy kit to increase self-use in a heat pump home. Start with these.
1) Heat hot water when the sun is strongest
If you have a hot water cylinder (common with heat pumps), it is an obvious thermal store.
A simple and effective approach:
- Schedule hot water heating around late morning to mid-afternoon on days with reasonable solar.
- Keep temperatures sensible (your installer will set safe minimums and legionella cycles).
This captures solar without overheating the house, and it works even in summer when space heating is low.
2) Gentle pre-heat on sunny shoulder-season days
In spring and autumn, solar and heating demand overlap more often. On a sunny day, a small shift can help:
- Let the home drift slightly warmer in the early afternoon.
- Then your heating needs are lower in the evening, when solar drops.
This works best in homes with reasonable insulation and some thermal mass. Keep it modest. You are trying to move a bit of load, not turn your home into a sauna.
3) Align “other electric” with your solar window
A heat pump adds a lot of electricity usage, but your other usage still matters.
The usual winners are:
- Washing machine, tumble dryer (if you must), dishwasher
- Cooking and pre-cooking
- EV charging, if relevant
Even small shifts add up because they increase the amount of solar you use directly, which is generally the most valuable kilowatt-hour.
Do batteries help with heat pumps?
Sometimes. Often. Not always.
A battery is good at one thing: moving solar from midday into the evening.
That can be useful in a heat pump home because evenings can be heating-heavy (and electricity-price heavy on some tariffs). But there are two important limits:
- A battery cannot create winter solar. In December, there is not much surplus to store.
- Heat pumps can drain batteries quickly. Space heating loads can be larger than most domestic batteries, especially on cold evenings.
So think of a battery as an optional bridge for daily timing, not a seasonal solution.
If you are considering a battery, it is worth comparing scenarios using your own postcode assumptions in the SolarByPostcode calculator.
Sizing solar for a heat pump: the rule that saves people money
The biggest mistake people make is sizing solar for winter heating.
In the UK, that pushes you towards over-sizing, which usually means:
- you export a lot in summer (often at a low rate), and
- you still import heavily in winter anyway.
A more realistic approach:
- Estimate your post-heat-pump annual electricity use (kWh; see Glossary).
- Choose a solar size that covers a meaningful share annually, without pretending it will cover winter heating.
- Use load shifting first, and treat a battery as a second-order optimisation.
If you are unsure how to think about kilowatt-peak (kWp; see Glossary) versus kilowatt-hours (kWh; see Glossary) (and why your app never hits brochure numbers), read:
- Why your solar panels will never hit their rated output
And if you want a direct sizing framework, see:
- Solar system sizing in the UK: choosing the right kWp without wasting money
Two related performance guides that help you sanity-check what “normal” output looks like in Britain:
- Temperature losses in UK solar panels: how heat quietly eats your kWh
- Cloud cover vs solar output: what actually happens on overcast UK days
A simple example: why postcode matters even more with heat pumps
A heat pump increases electricity consumption everywhere, but solar yield is still postcode-sensitive.
Imagine two similar homes that both add a heat pump and see their electricity use rise. One is in Truro (TR1), the other in Aberdeen (AB10).
TR1 typically has stronger solar yield than AB10. That difference does not just change annual kWh. It changes how much of the new heat pump load can realistically be covered by solar across the year.
The right sizing choice is not a UK average. It is a postcode question.
Seasonal load balancing: what “good” looks like
If you want an intuitive target, aim for this behaviour:
- Winter: accept that you will import. Optimise the heat pump for efficiency, not for chasing solar.
- Spring and autumn: maximise overlap through hot water timing and gentle pre-heat on sunny days.
- Summer: use solar for hot water, and if you have reversible cooling, that can line up very well with solar peaks.
That is the real pairing. Not winter magic, but year-round optimisation.
Installing both at once: the order that avoids expensive mistakes
If you are planning solar and a heat pump together, the best sequencing is usually:
- Reduce heat demand first (insulation, draught-proofing, sensible controls).
- Size the heat pump based on the improved heat loss.
- Then size solar based on your new electricity demand and your roof.
This avoids oversized heat pumps and oversized solar arrays built on the wrong assumptions.
Frequently asked questions
Will solar run my heat pump in winter?
Not in any meaningful “self-sufficient” way for most UK homes. Winter solar is low and heating demand is high. Solar can still contribute, but treat winter as an import season.
Does a heat pump make solar more worthwhile?
Often, yes. Higher electricity consumption can increase self-use, which typically improves solar economics, especially in spring and autumn.
Is a battery required with a heat pump?
No. Many homes do well with smart timing (hot water midday, sensible pre-heat) and no battery. A battery can help shift evening usage, but it is optional.
How big should my solar system be if I have a heat pump?
Start from annual electricity use (after the heat pump), then size for annual value, not for winter heating. For a practical framework, use our solar system sizing guide and then sanity-check with your postcode in the calculator.
What is the easiest “win” without buying anything?
Move hot water heating into the solar window when possible. It is simple, it is usually safe, and it often gives a noticeable self-use boost.
Bottom line
Solar and heat pumps are not a “perfect match” because solar runs winter heating. They are a perfect match because a heat pump increases electricity demand, and solar is most valuable when you can use your generation directly.
Get the mindset right:
- accept the seasonal mismatch,
- focus on spring and autumn overlap,
- shift hot water and a bit of heating into the solar window,
- treat a battery as an optional bridge.
Next reads
- How much electricity does the average UK home actually use?
- Daytime vs evening electricity use: why timing matters more than totals
- Solar system sizing in the UK: choosing the right kWp without wasting money
- Can solar cover 100% of a UK home’s electricity? The honest answer
- Solar payback periods in the UK: what actually drives the number
Ready to model your area? Run your postcode through the SolarByPostcode calculator.