With the rising costs of energy and the push for sustainable living, many homeowners are exploring whether they can run a heat pump using solar power. On paper, it seems like the perfect combination: solar panels generate free electricity, and heat pumps offer highly efficient heating. However, in the UK, there are some key challenges that make this setup less straightforward than it appears.

In this guide, we’ll explore how heat pumps and solar panels work together, the limitations of this combination, and alternative solutions to maximise efficiency.

How Heat Pumps Work:

A heat pump extracts heat from the air, ground, or water and transfers it into your home. This process is incredibly efficient, often providing 3-4 times more heat energy than the electricity it consumes. However, a heat pump still requires electricity to operate, which is where solar PV comes in.

How Solar PV Works:

Solar panels convert sunlight into electricity. This power can be used directly in your home, stored in a battery, or exported to the grid. However, solar energy production is highly dependent on sunlight availability, which creates a challenge for heating in the UK.

The Seasonal Mismatch Problem:

One of the biggest drawbacks of relying on solar power to run a heat pump is the seasonal energy mismatch. In the UK:

• Solar panels generate the most energy in summer, when heating demand is lowest.
• Heating demand peaks in winter, when solar generation is significantly lower.

This means that during the months when you need heating the most, solar PV will not be producing enough power to support the heat pump.

Competing Energy Demands:

Another key issue is that solar power isn’t just used for your heat pump—it also powers your entire home, including:

• Lights
• Kitchen appliances
• TVs, computers, and other electronics
• Electric vehicle chargers (if applicable)

Since heat pumps require a considerable amount of electricity, most households will find that their solar generation is insufficient to fully power both the heat pump and their daily energy needs.

How Much Solar PV Do You Need to Run a Heat Pump?

A typical air-source heat pump requires around 2,500 to 5,000 kWh per year, depending on the size of your home and insulation levels. Meanwhile, a 4kW solar panel system in the UK produces around 3,500 kWh per year, but most of this energy is generated in spring and summer, when heating is not needed.

To fully run a heat pump on solar power in winter, you would need a significantly oversized solar PV system—which is often impractical due to space and cost constraints.

Possible Solutions to Improve Efficiency:

1. Pairing Solar with Battery Storage

Batteries allow you to store excess solar energy from the daytime to use at night. However, batteries are not a perfect solution for seasonal energy storage—they typically store power for hours or days, not months. This means they can help with short-term energy needs but won’t solve the winter solar shortfall.

2. Using an Off-Peak Electricity Tariff

Since solar alone won’t be enough to power your heat pump year-round, consider using an off-peak electricity tariff (such as Economy 7 or Agile Octopus). This allows you to run your heat pump at night when electricity prices are lower, reducing costs while still using grid electricity.

3. Combining Solar PV with Other Renewable Energy Sources

Some homeowners integrate solar PV with wind power or thermal solar systems to provide more consistent energy generation throughout the year. However, this requires additional investment and planning.

Is It Worth Running a Heat Pump on Solar Power in the UK?

While solar power can help reduce the running costs of a heat pump, it is not a standalone solution for heating in the UK. Due to the seasonal mismatch and competing energy demands, most homes will still need to rely on grid electricity—especially in winter.

Pros:

✅ Solar can offset some electricity costs, reducing reliance on fossil fuels.

✅ Works well in conjunction with battery storage and off-peak tariffs.

✅ More sustainable than gas or oil heating.

Cons:

❌ Solar generation is highest in summer, but heating is needed in winter.

❌ Heat pumps require a lot of electricity, and solar must also power other appliances.

❌ A large solar system would be required to make a significant impact, which is expensive and space-consuming.