Solar for Heat Pumps: Everything You Need to Know

By Kami Turky

Last Updated:

Solar power is an unstoppable force in the world of renewable energy, but it’s not just powering our lights and electronics.

With the help of solar-assisted heat pumps, you can now harness the power of the sun to help your home stay warm in winter.

They work by using the naturally occurring heat of the sun to supplement or replace your traditional heating system.

In this article, I’ll walk you through the basics of solar-assisted heat pumps, from how they work to the benefits and how much they cost.

Key Takeaways

  • A solar-assisted heat pump is a hybrid system that combines a heat pump with solar collectors to collect energy from the sun
  • The solar collectors collect heat through their absorber plates and then transfer the heat to a thermal fluid that absorbs heat and then repels it back to the system
  • The evaporator then converts the liquid refrigerator refrigerant into a vapor which is then compressed, transferred to the condenser, and condensed back into a liquid
  • After that, the liquid is passed through a heat exchanger which transfers the energy from the liquid to heating water
  • Solar-assisted heat pumps are highly efficient, reduce energy consumption and costs, and provide renewable energy that helps keep our environment clean
  • Solar-assisted heat pumps cost between $2,500 and $6,000 depending on the type and size of the system

What Is a Solar-Assisted Heat Pump?

A solar-assisted heat pump, or SAHP, is a hybrid heating system that combines a heat pump with a solar collector.

The solar collector gathers heat from the sun and transfers it to a heat pump.

The heat pump then takes the solar-generated heat and warms your home or business more efficiently than traditional heating systems.

Just like solar hot water systems, they collect energy from the sun to heat your water.

But the only difference is that they can work on cloudy days and during the night as they can extract heat from the outside air.

How Does a Solar-Assisted Heat Pump Work?

SAHPs can be configured in many different ways, but they mainly include 5 components:

1. Solar Collector

Of course, you know PV solar panels that absorb the sunlight and convert it into electricity.

Well, we have another type of solar panel, known as the thermal panel.

It works similarly to the PV solar panel except it collects heat, not electricity.

When sunlight hits the thermal panels, they absorb the heat through their absorber plates.

The generated heat is then transferred to a refrigerant fluid that absorbs the heat and circulates it back to the heat pump.

There are many types of solar collectors used in SAHPs, including:

  • Flat Plate Collectors: They contain large flat absorber plates that transfer heat to the refrigerant fluid within the solar collector. They are super efficient when the sun is at its peak, so they’re perfect for warm climates.
  • Evacuated Tubes: They are composed of several rows of parallel tubes with a refrigerant fluid inside. The heat is absorbed by the tubes, resulting in a high-efficiency rate even when the sun is low. They are also prone to overheating, so they’re best used in cooler climates.
  • PV-T or Hybrid: This is a combination of a PV solar panel and a thermal collector. When the PV panel absorbs sunlight, it only converts light into electricity. The excess heat is transferred to the thermal panels, which then transfer it to the refrigerant fluid.
  • Thermodynamic Collector: This type of solar collector depends on collecting heat from both the sun and the ambient air. They heat the refrigerant fluid as it passes through the collector and then transfer it to the heat pump

2. Evaporator

After the solar collectors heat the refrigerant fluid, the evaporator then converts the liquid refrigerant into a gas.

This process is called “evaporation” and it requires energy, which comes from the heat created by the solar collectors.

In direct expansion systems, the absorber in the collector acts as the evaporator, so the gas is transferred directly to the compressor.

In indirect expansion systems, there is a closed loop between the collector and the evaporator.

The gas is pumped from the solar collector to the evaporator, which then transfers it to the compressor.

3. Thermal Exchange Valve

The thermal exchange valve regulates the flow of refrigerant from the evaporator to the compressor.

It ensures that the heat pump runs efficiently and prevents any overloading.

For example, the valve will close if there’s too much heat from the solar collectors, preventing it from entering the compressor.

So, it will protect the system from damage and will prevent any energy waste.

4. Compressor

The main role of the compressor is to compress the low-pressure gas from the evaporator into a high-pressure gas.

This process helps to concentrate the heat in the gas, making it easier for the heat pump’s condenser to absorb and store the heat.

The compressor needs electricity to run, either fossil fuel or electricity generated by PV solar panels.

I’d recommend using PV-T solar collectors we discussed earlier which will be a great way to generate the electricity and heat needed to run your SAHP.

5. Storage Heat Exchanging Tank

The pressurized gas from the compressor passes through the heat exchanger or condenser.

The condenser releases the heat from the pressurized gas and transfers it to a storage tank of water.

Now, the heated water is stored in the tank, ready to be used for heating your pool with solar energy.

After the heat is stored, the refrigerant gas travels through an expansion valve where its pressure and temperature are reduced.

This helps to convert it back into a liquid state before it enters the evaporator again and starts another cycle.

What Are the Benefits of a Solar-Assisted Heat Pump?

Like all other solar energy systems, an SAHP offers significant environmental benefits. Some of these include:

  • Cost-Effective: Solar-assisted heat pumps don’t need oil or fuel to run, so they are much cheaper to operate than traditional heating systems
  • Environmentally Friendly: SAHPs generate nearly zero emissions and don’t contribute to global warming or air pollution
  • Reliability and Low-Maintenance: They have fewer moving parts than other heating systems, so they are more reliable and require less maintenance
  • Consistent Heat: SAHPs can generate heat consistently even on cloudy days and during the night. They collect heat from the ambient air, which is usually available even when there’s no direct sunlight

How to Evaluate the Efficiency of Solar-Assisted Heat Pumps?

One thing that you should keep in mind when evaluating the efficiency of an SAHP is its COP or coefficient of performance.

This is defined as the ratio between the heat provided by the system and the energy used to operate it, including both electricity and heat from solar collectors.

A higher COP value indicates that your system is more efficient, while a lower value means that you are wasting energy and not getting the most out of your system.

In general, you should look for a SAHP with a COP of 3 or higher — this will give you the best return on your investment.

How Much Does a Solar-Assisted Heat Pump Cost?

A solar-assisted heat pump typically costs anywhere from $2,000 to $6,000 depending on the size and type of system you choose.

If you decide to install PV-T solar collectors to generate electricity for your SAHP, then the cost will be higher.

At the same time, solar-assisted heat pumps working on thermodynamic collectors are more affordable and still high level of efficiency.

Is a Solar-Assisted Heat Pump Right for Me?

You can decide whether a solar-assisted heat pump is the right choice for you by taking into account several factors.

First, consider your energy needs and how much of it can be generated by a SAHP.

For example, if you want to heat your entire home, then an SAHP may not be the best option, as it can only provide a limited amount of energy.

Next, think if you have enough area to install the necessary solar collectors.

You need to have enough room for solar collectors on a roof or in a yard to make the most of your SAHP.

The other components also need suitable space to be installed, so it’s important to plan ahead and determine if you have enough room.

Finally, think about the costs of a solar-assisted heat pump.

If you have the budget and the space, then an SAHP is definitely worth considering.

But if you’re on a budget or are looking for something less costly, then you may want to consider other heating options.


Can I Run a Heat Pump With Solar Power?

You can power a heat pump with solar energy. However, the amount of energy produced will depend on the size of your solar panels and how much sunlight is available.

How Many Solar Panels Does It Take to Run a 1-Hp Pump?

It takes about six 200-watt solar panels to run a 1 hp pump. But this will still depend on the size of the pump, how much sunlight is available, and other factors.

How Many Solar Panels to Run a Heat Pump?

You need 8-23 solar panels to run a heat pump, depending on the size of the unit and other factors.


As promised, we’ve explored the basics of solar-assisted heat pumps and how they can be an effective and efficient option for your home.

And if you ask me, I’d recommend turning all your use of electricity to solar-powered sources.

I hope this article has helped. If you still have questions, feel free to leave them in the comments section below.

Kami Turky

Kami is a solar engineer with nearly a decade of experience in researching, testing, and reviewing various solar products. He has also provided technical consultation to several organizations on the best ways to incorporate solar energy into their operations. When he’s not busy helping others find the best solar solutions, Kami enjoys spending time outdoors, hiking, camping, and exploring the natural wonders of his home state.

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