Solar Assisted Heat Pumps | SAHP Cost & Benefits UK

A solar assisted heat pump (SAHP) is a smart system that uses both sunlight and air to heat your home’s water efficiently. It works by drawing in heat from direct sunlight and the surrounding air via a large, flat panel known as an evaporator.

This panel contains a special fluid that absorbs the captured heat and transfers it to the heat pump through a heat exchanger. The heat pump then raises the temperature further and stores the hot water in a cylinder, ready for you to use whenever you need it.

In essence, you’re combining the benefits of solar energy and heat pump technology in one setup.

If you want to cut energy costs and make your home more eco-friendly, a solar assisted heat pump is an appealing option. In this article, we’ll explore exactly how a solar assisted heat pump works, the benefits it offers, what it costs and whether it could be the right choice for you.

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What is a Solar Assisted Heat Pump?

A solar assisted heat pump, also known as a SAHP, is a renewable heating system that combines solar technology with a heat pump to produce energy-efficient hot water. Instead of relying solely on sunlight or outdoor temperatures, the heat pump uses both, capturing warmth from the sun and the air to heat your home’s water supply.

The system includes a solar panel, known as an evaporator, which collects sunlight as well as heat from the surrounding air. This captured energy is absorbed by a refrigerant fluid inside the panel. The fluid then passes through the heat pump, where the temperature is increased and the heat is transferred into a hot water cylinder, ready for use in the household.

Since it's powered by natural, renewable energy, a solar assisted heat pump uses far less electricity than a traditional water heater. It can also still provide hot water on cooler or cloudy days, making it an efficient year-round solution for homes in the UK.

How Does a Solar Assisted Heat Pump Work?

A SAHP works by combining solar energy and heat pump technology to heat your water in an efficient and sustainable way.

The system uses a large, flat panel known as an evaporator, which absorbs warmth from both the sun and the surrounding air. Inside this panel is a special heat transfer fluid that captures the collected energy and carries it through to the heat pump. Once inside the heat pump, the temperature is increased further through a heat exchanger, and the heat is then transferred into your hot water cylinder, ready for everyday use.

Depending on how your system is set up, the solar energy can come from two different sources, either solar thermal collectors or solar photovoltaic (PV) panels. In solar thermal setups, the heat from the sun and air is directly absorbed by the panel to warm the transfer liquid before it reaches the heat pump. Since the liquid enters the system already warm, the pump needs less energy to bring your water up to temperature.

If your SAHP uses solar PV panels instead, these panels turn sunlight into electricity, which powers the heat pump. The heat pump then draws heat from the air to produce hot water, while using significantly less grid electricity.

It’s worth noting that a solar assisted heat pump provides a steady supply of efficiently heated water rather than producing large volumes all at once. This means that after using a full tank of hot water, it may take a little time for the system to reheat the cylinder. Even so, the overall energy use remains low, giving you reliable hot water while reducing your carbon footprint and running costs.

Types of Solar Assisted Heat Pumps

There are two main types of SAHPs, solar thermal-assisted and solar photovoltaic-assisted systems. Both use renewable energy from the sun, but they work in different ways to help heat your home’s water more efficiently.

Solar Thermal Assisted Heat Pumps

In a solar thermal-assisted system, heat is collected directly from the sun and the surrounding air through flat thermodynamic panels or solar collectors. These panels contain a special fluid that absorbs the captured heat and carries it into the heat pump. The pump then boosts the temperature and transfers that heat into your hot water cylinder. Since the water entering the system is already warm, the heat pump doesn’t need to work as hard, which helps lower your energy bills and reduce wear on the system.

Solar Photovoltaic Assisted Heat Pumps

A solar PV-assisted system, on the other hand, uses solar panels to generate electricity from sunlight. This electricity is then used to power the heat pump, allowing it to extract heat from the air without drawing as much from the national grid. It’s an ideal choice if you already have or plan to install solar PV panels, as the electricity they produce can directly support your home’s heating and hot water needs.

Ultimately, both system types aim to maximise the free, renewable energy available from the environment. The main difference is how they use solar power, either capturing heat directly from sunlight or converting it into electricity to help the heat pump do its job.

Recommended Reading: Can Solar Panels Power A Heat Pump?

Benefits of Solar Assisted Heat Pumps

Investing in a solar assisted heat pump comes with a range of practical and environmental advantages that make it an appealing choice for many:

You can significantly cut your energy bills

One of the biggest advantages of a solar assisted heat pump is the reduction in running costs. By using free energy from the sun and the air around your home, you rely far less on electricity from the grid.

This means your monthly energy bills can potentially drop noticeably compared to conventional electric or gas water heating systems. Over time, these savings can make a big difference, especially as energy prices continue to fluctuate in the UK.

You’ll reduce your carbon footprint

Since a solar assisted heat pump uses renewable energy sources, it produces much lower carbon emissions than traditional heating systems. You’re essentially using nature’s free resources, sunlight and air, to heat your water instead of burning fossil fuels. It’s a simple, effective way to make your home more sustainable and contribute to a cleaner environment.

You’ll have reliable hot water all year round

A common misconception is that solar systems only work when it’s sunny, but solar assisted heat pumps perform efficiently even on cloudy or cooler days. That’s because the system also draws heat from the surrounding air, not just direct sunlight. This combination allows you to enjoy a consistent supply of hot water throughout the year, no matter the season.

You can benefit from low-maintenance technology

Once installed, a solar assisted heat pump requires very little upkeep. The system is designed to operate automatically, and most units are built to be durable and weather-resistant. Annual servicing by a certified technician is usually all that’s needed to keep everything performing efficiently for many years.

Recommended Reading: Air Source Heat Pump Maintenance

You could access government incentives and boost your home’s value

In the UK, installing a renewable heating system like a solar assisted heat pump may make you eligible for heat pump grants or tax advantages. Also, energy-efficient homes are becoming more attractive to buyers. By installing a SAHP, you not only lower your running costs but could also potentially increase your property’s overall value and appeal.

Drawbacks of Solar Assisted Heat Pumps

As we've mentioned above, installing a solar assisted heat pump offers many benefits, but it’s also important to understand the potential drawbacks before deciding if it’s right for your home:

You may face higher upfront costs

Solar assisted heat pumps typically cost more to install compared to standard heat pumps, as you’re combining two systems. While these costs can be offset over time through energy savings and incentives, the initial investment can be a barrier for some.

Recommended Reading: Heat Pump Costs

You need suitable space for installation

For the system to work efficiently, you’ll need enough space to fit the evaporator panel or solar collectors, as well as the heat pump and hot water cylinder. Homes with limited roof or ground space may find it difficult to accommodate the setup. In some cases, property layout or shading from buildings and trees can reduce solar performance.

Recommended Reading: Is My Home Suitable for a Heat Pump?

You may experience slower recovery times for hot water

Since a solar assisted heat pump heats water gradually and in lower volumes, it can take longer to reheat your hot water cylinder after heavy use. If your household has high hot water demands, you may need a larger cylinder or tailored system design to avoid running out.

You depend on both sun and air conditions

While SAHPs can operate in cooler and cloudier weather, their efficiency is still affected by how much solar energy and ambient heat they can collect. In colder months or heavily overcast areas, the solar contribution will be lower, which could slightly increase reliance on grid electricity.

You may require professional maintenance

Although SAHPs are generally low-maintenance, they do include multiple components. To keep everything working at its best, you’ll need occasional professional servicing, which can add to long-term upkeep costs.

How Efficient Are Solar Assisted Heat Pumps?

By combining solar energy with heat pump technology, SAHPs use less electricity than traditional water heating methods because they capture free renewable heat from the sun and the air around your home. This makes them highly efficient.

Though, the efficiency of a solar assisted heat pump depends on several key factors. When the solar panels receive direct sunlight, the surrounding air temperature is fairly warm and you’re heating water to a moderate temperature, the system performs very well. Under these ideal conditions, the heat pump can deliver plenty of hot water while using minimal electricity.

However, if any of these conditions change, such as reduced sunlight during cloudy days or lower air temperatures in the winter, the system’s efficiency can decline. For example, at night or in colder months, there’s less sunlight and the ambient temperature drops, making it harder for the heat pump to extract heat. As a result, the amount of heat produced may be lower, requiring more energy input.

The system also works best when the water temperature you need isn’t set too high, since the heat pump uses less energy to warm water to moderate temperatures.

How Much Do Solar Assisted Heat Pumps Cost?

The price of a solar assisted heat pump can vary quite a bit depending on the size of your home, the type of system you choose and how much hot water you need (among other factors). According to Energy Saving Trust, you could typically pay around £6,000.

When comparing prices, remember that a solar assisted heat pump combines two systems, the heat pump itself and the solar thermal or PV panels. This means the upfront cost is usually higher than for a standard heat pump or conventional boiler, but you’re also getting improved efficiency and the potential for bigger savings on your energy bills over time.

There are also government grants and incentives available in the UK that can help reduce your initial costs. For example, schemes like the Boiler Upgrade Scheme (BUS) may provide funding towards the cost of a qualifying renewable heating system, including SAHPs. Taking advantage of these grants can make installation much more affordable and help you see a return on your investment sooner.

You should also consider the running costs and savings you’ll see each month. Since a solar assisted heat pump uses free solar energy and relies less on electricity from the grid, your energy bills will likely decline, making the system more cost-effective in the long term.

Recommended Reading: How Much Does an Air Source Heat Pump Cost?

What affects the cost of a solar assisted heat pump?

Several key factors will determine how much you’ll pay for a solar assisted heat pump system:

• The size and hot water needs of your home.

• The type of system (solar thermal-assisted or solar PV-assisted).

• The number and quality of solar panels or evaporator panels required.

• Complexity and scale of installation work.

• Existing heating and plumbing setup in your property.

• Whether you need a new hot water cylinder.

• Amount of available roof or ground space for panels.

• Access to government grants or local incentives.

• The installer’s experience and reputation.

Is a Solar Assisted Heat Pump the Best Fit for My Home?

Whether a solar assisted heat pump is the best fit for your home comes down to how you plan to use your heating system and the space you have available. If your main concern is heating both your home and your hot water, it’s worth exploring traditional air source or ground source heat pumps, which are designed to handle both space heating and hot water needs efficiently.

However, if you’re mainly interested in an energy-efficient way to produce hot water and want to lower your running costs, a SAHP could be a strong option.

You’ll also need a roof or suitable wall space to mount the evaporator panel (this panel works best in a sunny spot). Bear in mind, most homes only need one or two panels for typical water heating requirements. Additionally, the size of the hot water cylinder you’ll need depends on your household’s usage levels, and many systems now come with an integrated cylinder to save on space.

To get the best value and performance from a SAHP, think about your household’s daily hot water needs, your available installation space and your willingness to wait for a cylinder to reheat after heavy use. If those needs align, a solar assisted heat pump could be right for you and your home.

Ultimately, we recommend contacting a qualified heat pump installer who can assess your home and offer tailored advice based on your specific requirements.

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