Solar panels and heat pumps work well together. The panels make electricity and the heat pump uses it to heat and cool the building. But they do not follow the same pattern through the year, and good design starts with understanding why.

Solar through the year

Solar panels produce the most electricity in summer. The days are long and the sun is high in the sky. In winter the days are short, the sun is low and there is more cloud, so production is much lower.

The pattern within each day matters too. Output rises from sunrise, peaks around the middle of the day and falls towards sunset. East- and west-facing panels spread this out across the morning and afternoon.

Heat pumps through the year

A heat pump used for heating does the opposite. It uses the most electricity in winter, when the building needs the most heat. It also has to work a little harder then, because the outside air is colder, so each unit of electricity gives less heat than it would in mild weather.

In summer, a heat pump that can cool will use some electricity on hot, sunny days. In spring and autumn it often needs very little.

Where they match and where they do not

Summer: plenty of solar and modest demand. Cooling needs line up well with sunny afternoons. There is often spare power.
Spring and autumn: a good balance. Moderate solar, moderate heating, and a heat pump working efficiently in mild weather.
Winter: the hardest season. Low solar and the highest heating demand.

How a good design handles the mismatch

There is no single fix, but several things work together.

Design for winter days, not just annual totals. We aim to capture the most useful energy each day, not only the biggest yearly number. East-west layouts help here by spreading output across short winter days.
Batteries for day and night. Batteries move energy from the afternoon to the evening and overnight. They are not designed to save summer sunshine for winter.
Store heat as well as electricity. Surplus solar can heat water in insulated tanks, sometimes called water batteries, ready for later use.
Reduce the winter demand. Better insulation means less heat is needed in the first place.
Plan for top-up. In winter most buildings will still draw some power from the grid. Off-grid sites use a generator to top up the batteries, ideally capturing its waste heat too.

Measure it

Energy monitoring shows exactly what the panels produce and what the heat pump uses, hour by hour and season by season. That makes it possible to adjust controls, spot problems early and plan improvements based on real numbers rather than guesses.

The short version

Solar is strongest in summer and heat pumps work hardest in winter. A system designed with that in mind, using batteries, heat storage, good insulation and sensible top-up, makes the most of free energy all year round.