Solar Assisted Heat Pumps

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Last Updated on 4th March 2024

Solar Assisted Heat Pumps In 2024

Solar Assisted Heatpumps (SAHPs), a technology that brings together solar thermal panels and heat pumps to provide cost-effective, efficient hot water. We will shed light on the following and more:

  • Best Solar Assisted Heatpumps - Hand-picked recommendations by the professionals at Glow Green.
  • Performance Enhancements - Tips and techniques to boost your SAHP's efficiency.
  • Case Studies & Research Findings - Real-world examples and scientific validations of SAHP effectiveness.
  • Benefits, Applications, & Considerations - A complete breakdown of why SAHPs could be the perfect fit for your home.
  • Comparisons - Understand how SAHPs stack up against other heating systems.

Government Incentives: In the UK, government schemes like the Boiler Upgrade Scheme offer grants of up to £7,500 to assist with the upfront costs of installing heat pump. While the scheme is explicitly mentioned for air source and ground source heat pumps, similar incentives may apply or become available for SAHPs, reducing the overall investment required.

What is a Solar Heat Pump?

What is a Solar Heat Pump?

A Solar Heat Pump, often referred to as a Solar Assisted Heat Pump (SAHP), is an innovative hybrid heating system that merges the principles of solar energy collection with the efficiency of heat pump technology to provide a sustainable method for space heating and hot water production.

This system utilises solar thermal panels to absorb solar radiation, which is then used to increase the temperature of a refrigerant or fluid within the heat pump circuit. The heat pump component amplifies this thermal energy through compression, efficiently transferring it to heat water or air for residential or commercial use.

Unlike traditional heating systems, SAHPs can significantly reduce reliance on fossil fuels and electricity by leveraging renewable solar energy, offering an eco-friendly, cost-effective solution that enhances energy efficiency and reduces carbon footprint.

Best Solar Assisted Heatpumps

Choosing the best solar assisted heatpump for your home depends on specific needs, including climate, household size, and budget. Here are some top contenders known for their efficiency and reliability:

8 Best Solar Assisted Heat Pumps in the UK

Solar Heat Pump ModelKey Feature
Grant Aerona R32 Considered the best on the market currently.
Dimplex System H6 HTi70Known for its efficiency.
LG Therma V R32 MonoblocRecommended for cold climates.
HydroPro ECO 12Ideal for swimming pools.
Vaillant flexoTHERM 400vKnown for its power.
MasterTherm UK BoxAir InverterOffers a seven-year warranty and is highly efficient.
Daikin Altherma 3 H HTConsidered the best for high temperature applications.
SAHP 200Cost-effective and green, can be combined with solar panels for renewable energy.

Let's dive a little more into each model:

1. Grant Aerona R32

Grant Aerona R32

The Grant Aerona R32 stands out as a top performer in the UK's solar heat pump market, known for its cutting-edge technology and remarkable efficiency.

  • Exceptional energy efficiency, reducing household energy costs.
  • Utilises R32 refrigerant, which has a lower environmental impact.
  • Quiet operation, making it ideal for residential use.
  • Higher initial cost compared to some other models.
  • Requires professional installation and setup.

2. Dimplex System H6 HTi70

Dimplex System H6

Renowned for its efficiency, the Dimplex System H6 HTi70 is a standout solar heat pump that delivers consistent performance and reliability.

  • High efficiency, offering significant savings on heating bills.
  • Advanced controls for easy operation and monitoring.
  • Suitable for a wide range of property sizes.
  • Initial installation can be complex.
  • May require additional space for optimal setup.

3. LG Therma V R32 Monobloc

LG Therma Designed for cold climates, the LG Therma V R32 Monobloc excels in providing efficient heating even in the chilliest conditions.

  • Exceptional performance in cold weather, ensuring comfort year-round.
  • Energy-efficient, leading to lower operating costs.
  • Compact design allows for easier installation in limited spaces.
  • On the higher end of the price spectrum.
  • May not be as efficient in milder climates.

4. HydroPro ECO 12

HydroPro ECO 12 The HydroPro ECO 12 is specifically designed for heating swimming pools, offering a cost-effective and environmentally friendly solution.

  • Ideal for swimming pool heating, extending the swimming season.
  • Energy-efficient operation reduces pool heating costs.
  • Easy to install and maintain.
  • Limited use outside of pool heating applications.
  • May require a separate system for household heating needs.

5. Vaillant flexoTHERM 400v

Vaillant flexoTHERM 400v Known for its powerful performance, the Vaillant flexoTHERM 400v is a versatile and robust solar heat pump suitable for larger homes and buildings.

  • High power output suitable for larger properties.
  • Versatile installation options.
  • Quiet operation and high reliability.
  • Higher initial investment.
  • May be more system than needed for smaller properties.

6. MasterTherm UK BoxAir Inverter

MasterTherm BoxAir Inverter Offering a seven-year warranty and high efficiency, the MasterTherm UK BoxAir Inverter is a reliable choice for those seeking long-term value.

  • Long warranty period provides peace of mind.
  • High efficiency translates to lower running costs.
  • Innovative inverter technology for optimal performance.
  • Premium pricing for advanced features.
  • Installation requires certified professionals for warranty validity.

7. Daikin Altherma 3 H HT

Daikin Altherma 3 H HT The Daikin Altherma 3 H HT is acclaimed for its high-temperature applications, delivering efficient heating even during the coldest months.

  • Excellent for high-temperature heating needs.
  • Energy-efficient, reducing overall heating costs.
  • Sleek design and quiet operation.
  • May require more upfront investment than some models.
  • Optimised for colder climates, which may limit its efficiency in milder conditions.

8. SAHP 200

SAHP 200 The SAHP 200 is an eco-friendly and cost-effective solution that integrates seamlessly with solar panels for renewable energy heating.

  • Combines with solar panels for enhanced green energy use.
  • Cost-effective, offering significant long-term savings.
  • Performance heavily dependent on solar panel efficiency.
  • May require additional space for solar panel installation alongside the heat pump.

How Much Does a Solar Assisted Heat Pump Cost?

The cost of installing a typical solar-assisted heat pump can hover around £6,000. However, this figure can fluctuate based on several factors, including the specific model you choose, the quantity of evaporator panels necessary for your setup, and the potential need for a hot water cylinder. Additional considerations, such as the requirement for extra pipework, scaffolding, or other installation-related tasks, can also influence the final price.

Capacity (kW)ASHP Cost (£)GSHP Cost (£)Solar Panel System Cost (£)Installation Cost (£)Government Grants Available
1-2 kW8,000 - 18,00014,500 - 45,0006,500 - 9,000 (4kW system)Varies; approx. 1,600 - 3,100Up to £7,500 (Boiler Upgrade Scheme)
3 kW8,000 - 18,00014,500 - 45,0007,000 - 8,000 (3kW system)Varies; approx. 1,600 - 3,100Up to £7,500 (Boiler Upgrade Scheme)
4 kW8,000 - 18,00014,500 - 45,0009,000 - 10,000 (4kW system)Varies; approx. 1,600 - 3,100Up to £7,500 (Boiler Upgrade Scheme)
5 kW8,000 - 18,00014,500 - 45,00011,000 - 12,000 (5kW system)Varies; approx. 1,600 - 3,100Up to £7,500 (Boiler Upgrade Scheme)
6 kW8,000 - 18,00014,500 - 45,00013,000+ (6kW+ systems)Varies; approx. 1,600 - 3,100Up to £7,500 (Boiler Upgrade Scheme)
  • ASHP Cost: The cost range for air source heat pumps, which can be part of a SAHP system[1][4].
  • GSHP Cost: The cost range for ground source heat pumps, another potential component of SAHP systems[3].
  • Solar Panel System Cost: Estimated costs for solar panel systems of various capacities. These systems can power heat pumps, making the setup a solar assisted heat pump system[4][5].
  • Installation Cost: Approximate range for installing air-to-air heat pumps, which could be similar for SAHP systems[2].
  • Government Grants Available: The Boiler Upgrade Scheme offers up to £7,500 for installing heat pumps, which could offset the total cost[1].


  • The costs are approximations and can vary based on specific system requirements, property size, and location within the UK.
  • Installation costs can vary significantly based on the complexity of the installation, the need for additional components (like underfloor heating or larger radiators), and the specific requirements of the property.
  • Government grants can significantly reduce the upfront cost of installing SAHP systems. Eligibility and exact savings should be confirmed with the relevant authorities or schemes.

This table provides a general overview of the costs associated with setting up a solar assisted heat pump system in the UK, combining the costs of heat pumps and solar panel systems, which are key components of SAHPs.

Sources:[1] [2] [3] [4] [5]

How Does a Solar Pump Work?

How Does A Solar Pump Work

Solar Assisted Heatpumps (SAHPs) are an innovative type of heating system that leverage the power of solar energy to produce hot water. The key ingredients in this process are a solar thermal panel and a heat pump. Together, these elements work to optimise energy efficiency and minimise electrical consumption.

1. Indirect-Expansion Configuration

Indirect-Expansion Configuration

The indirect-expansion configuration is one of two main types of SAHPs. In this setup:

  • A solar thermal panel absorbs heat from the sun.
  • This heat is transferred to an antifreeze fluid circulating through the system.
  • The warm antifreeze fluid then passes through a heat exchanger, which transfers the heat to a refrigerant.
  • The refrigerant, now in a gaseous state, flows into a compressor where its pressure and temperature increase.
  • The hot refrigerant then moves into a condenser, where it transfers its heat to water.
  • As it loses heat, the refrigerant returns to a liquid state. It circulates back to the evaporator, ready to absorb more heat from the antifreeze fluid.

So, what's with the antifreeze fluid?

Antifreeze plays a crucial role in maintaining system efficiency. It allows SAHPs to continue operating even at sub-zero temperatures by preventing freezing in the solar thermal panel.

While this configuration is effective, it's not without challenges. One significant hurdle is balancing performance with electrical consumption reduction – an essential aspect for achieving optimal energy efficiency.

In an indirect-expansion system:

  • The performance refers to how much hot water the system can produce.
  • Electrical consumption reduction measures how much less electricity the system uses compared to traditional heating methods.

Striking a balance between these two factors requires careful calibration of system components and settings. Too much emphasis on performance might lead to excessive electrical consumption, while prioritising electricity reduction could compromise the system's capacity to produce enough hot water.

2. Direct-Expansion Configuration

Direct-Expansion Configuration

A second approach to Solar Heat Pump is the Direct-Expansion Configuration. This system directly integrates a refrigerant fluid into the solar thermal panels, making it distinct from the Indirect-Expansion Configuration which utilises an antifreeze fluid.

The way it operates is by circulating this refrigerant fluid through the solar thermal panels. As the fluid absorbs heat from both sunlight and ambient air, it evaporates into a gas. It then passes through a compressor, which raises its temperature even further. The hot gas transfers its heat to the water in a storage tank, and then it condenses back into a liquid to restart the cycle.

Advantages of Direct-Expansion Configuration

One of the primary benefits of this configuration is that it eliminates the need for an intermediary heat transfer fluid or exchange loop. This characteristic leads to several advantages:

  • Efficiency: The direct expansion of refrigerant in solar thermal panels means there's less energy loss in heat transfer processes, leading to higher overall system efficiency.
  • Hot water generation: The heated refrigerant can produce hot water at temperatures up to 60°C, making it suitable for a variety of residential and commercial applications.
  • Electrical consumption: The reduction in energy losses also translates into lower electrical energy consumption. This feature makes Solar Assisted Heatpumps with Direct-Expansion Configuration an attractive choice for those aiming to minimize their energy footprint.

Challenges of Direct-Expansion Configuration

However, along with these benefits come some challenges. One such challenge is the need for careful control of refrigerant flow and compression rates to prevent performance drop-offs at low radiation levels or high hot water demand situations.

In essence, while the Direct-Expansion Configuration offers significant potential for efficient use of solar energy and reduced electricity consumption, its successful implementation requires careful system design and operation management.

Before moving on to enhancing the performance of these systems, it is crucial to consult with a certified professional to evaluate which heat pump aligns best with your objectives and site conditions.

Performance of Solar Assisted Heatpumps

Performance of Solar Assisted Heatpumps

Double Cold Source Configuration

Solar Assisted Heatpumps (SAHPs) can achieve greater energy savings with an innovative approach known as the Double Cold Source Configuration. This configuration leverages two separate cold sources:

  1. Ambient Air: Typically used in traditional heat pump systems, ambient air serves as a primary cold source.
  2. Evaporator Panel: An additional evaporator panel, exposed to the environment, acts as a secondary cold source.

How It Works:

The system switches between these cold sources based on their availability and efficiency at any given time. During colder periods, when the ambient air temperature is lower, the system primarily uses the evaporator panel to extract heat. Conversely, during warmer conditions or periods of insufficient solar radiation, the system can switch back to using ambient air.

Energy Saving Potential:

  • Improved Efficiency: By selecting the most efficient cold source at any time, SAHPs with double cold source configurations can operate more efficiently than those relying on a single cold source.
  • Reduced Electrical Consumption: This configuration minimises reliance on electrical resistance heating elements commonly used during low ambient temperature conditions in traditional heat pumps.

System Complexity Considerations:

  • Increased Components: Incorporating an additional evaporator panel and control mechanisms adds complexity to the installation and operation.
  • Maintenance: With more components, there is potential for higher maintenance requirements over time.
  • Cost: Initial [setup costs][(/solar-advice/solar-panel-installation-costs-prices)] may be higher due to additional materials and sophisticated control systems needed for optimal operation.

Despite these considerations, the long-term benefits associated with energy savings often justify the increased complexity for consumers focused on maximising efficiency and reducing their carbon footprint.

PV Cells Cooling Improvement

PV Cells Cooling Improvement

Effective cooling of Photovoltaic (PV) cells plays a critical role in enhancing overall energy efficiency in Solar Assisted Heatpumps systems. As PV cells convert sunlight into electricity, they inevitably generate heat—a portion of which can be detrimental to their performance if not managed properly.

Strategies for Cooling PV Cells:

  1. Passive Ventilation: Designing systems with natural airflow can help dissipate heat without consuming additional energy.
  2. Heat Sinks: Attaching metal plates or fins that conduct and radiate heat away from the PV cells aids in maintaining lower operating temperatures.
  3. Active Cooling: Utilising liquids or forced-air systems controlled by thermostats can effectively reduce PV cell temperatures and improve efficiency.
  4. Thermal Energy Storage: Excess heat from PV cells can be stored in thermal batteries for later use, creating a dual-benefit scenario.

These cooling methods not only prevent overheating but also improve PV cell lifespan and performance. When integrated smartly within SAHPs, they contribute to a system that not only saves on electrical consumption but also enhances renewable energy generation.

By implementing these enhancements—Double Cold Source Configuration and improved PV cells cooling—SAHPs become a formidable technology in the quest for eco-friendly and cost-saving heating solutions.

Case Studies and Research Findings

Case Studies

Solar-assisted heat pumps in the UK have a variety of experiences from users, ranging from great satisfaction to challenges primarily due to property insulation levels and climatic factors.

"What makes ASHP less viable in the UK is the cost of electricity and the state of insulation in many UK properties... a well-designed ASHP will cost about the same as gas per unit of energy. Insulation does not change the cost of one kWh of heat, it just means you use less."[1]

"Heat pumps are more efficient with low-temperature emitters... One way to achieve this is to leave the radiators and improve insulation"[1]

Cost Efficiency

"Heat pumps are expensive, particularly because of installation costs. Variable costs can be very low but the initial investment is large"[1]

"Excellent so far. Warm house, not too expensive, and now we have solar and batteries installed, it's cheap to run too"[2]

Performance and Seasonality

"It just seems to maybe increase efficiency in the shoulder season, but that's not a serious problem?"[3]

"And I don't think you're going to get much assist in winter in the UK, for example, there's only 2 average hours of sunlight per day in December and January in London"[3]

Reliability Concerns

"Less moving parts than normal heat pumps, so should be even more reliable"[3]

"We have had this installed about a month ago and it’s absolutely terrible... It uses CO2 so it's high pressure and I believe they were having leakages with the equipment" [3]

Government Grants and Incentives

"The grant BTW has recently changed to £7500 so go for it while it lasts if your house insulation is done as heat pump sizing is based on house heat leakage"[2]

Sources: [1] [2] [3]

Article Summary:

  • SAHPs offer superior room heating capabilities compared to traditional heat pumps.

  • They require less installation space than solar thermal systems.

  • Their overall energy efficiency is greater than both traditional heat pumps and solar thermal systems. Therefore, for consumers seeking an efficient, space-saving, and reliable heating solution, Solar Assisted Heatpumps emerge as a strong contender.

Solar-Assisted Heat Pump FAQS


What are solar-assisted heat pumps and how do they work?

Solar-assisted heat pumps (SAHPs) are systems that combine solar energy collection with heat pump technology to provide heating and cooling for residential buildings. They use solar panels with a heat exchanger on the backside to absorb energy from the environment, which is then used as a source for the heat pump. This can be beneficial as it reduces the reliance on external electricity or gas for heating and cooling.

Are solar-assisted heat pumps popular and where are they commonly used?

While not as widespread as traditional heat pump systems, solar-assisted heat pumps are gaining traction in countries like the UK, Saudi Arabia, and Costa Rica. They are suitable for climates like the UK where they can operate efficiently even in temperatures down to about -10°C.

What are the advantages of solar-assisted heat pumps?

The main advantages include the potential for increased efficiency, especially during shoulder seasons, and the use of renewable solar energy which can reduce electricity bills. They also tend to have fewer moving parts than conventional heat pumps, which could lead to higher reliability and lower maintenance costs.

What are the disadvantages of solar-assisted heat pumps?

Some users have reported issues such as insufficient heating, noisy compressors, and system complexity. Additionally, the initial capital expense may not be justifiable for all users, especially if the operational savings are not significant. There are also concerns about the efficiency of the system during the winter months in regions with limited sunlight.

Can solar-assisted heat pumps be used for cooling as well?

Yes, solar-assisted heat pumps can be used for cooling. However, there are concerns that using the system for cooling might lead to overheating the solar panels, which could negatively affect efficiency and the lifespan of the panels.

How do solar-assisted heat pumps compare to separate solar panels and heat pump systems?

Some users believe that having separate solar panels and a heat pump might be more beneficial if there are no building constraints. This allows each system to operate optimally without the potential drawbacks of combining the technologies.

What are the considerations for installing a solar-assisted heat pump?

When considering installation, it's important to assess the climate suitability, the potential for solar energy collection, and the specific heating and cooling needs of the residence. It's also crucial to consider the cost of installation versus the expected energy savings over time.

How do solar-assisted heat pumps perform in cold climates?

In cold climates, solar-assisted heat pumps can perform well, particularly in regions like the UK or where temperatures do not typically drop below the operational range of the system. However, their performance may be less efficient in areas with extreme cold and limited sunlight during winter.

What are the energy consumption and output characteristics of solar-assisted heat pumps?

Typically, these systems consume about 500W of energy when on and can heat a water tank to 55°C. They activate when the temperature drops by 5°C. The size of the system, such as the water tank capacity, can vary based on the needs of the household.

How much do solar assisted heat pumps cost to run?

The running costs for a solar assisted heat pump are generally affordable, with annual electricity expenses typically ranging from £80 to £100. This makes it an economically viable option for many homeowners looking to reduce their energy bills.

Can solar-assisted heat pumps be integrated with other renewable energy systems?

Yes, solar-assisted heat pumps can be integrated with solar photovoltaic (PV) systems. Some systems allow for excess electricity generated by solar PV to be used to heat the water tank, increasing overall efficiency.

What are the maintenance requirements for solar-assisted heat pumps?

While specific maintenance requirements are not detailed in the search results, it is generally mentioned that solar-assisted heat pumps have fewer moving parts than traditional heat pumps, which could imply lower maintenance needs.

What is the difference between solar thermal and heat pump?

Solar assisted heat pump systems harness both the ambient air's heat and the sun's rays to efficiently provide hot water for homes. Unlike traditional solar thermal systems, which rely exclusively on solar panels or collectors to capture the sun's energy for water heating, these innovative setups combine the best of both worlds. This dual-source approach not only increases the system's efficiency but also ensures a more consistent supply of hot water, even during less sunny periods, by utilising the ambient air temperature as a supplemental heat source.

Article Sources

[1] [2] [3]