PVT Modules Explained: Function, Benefits and Cost-Effectiveness

PVT modules combine electricity and heat generation on the same surface, thereby increasing the energy yield per square meter. According to the IEA Solar Heating & Cooling Programme, a PVT system delivers three to four times more usable total energy per area than pure photovoltaics.

At first, that sounds like a no-brainer. Nevertheless, in this article I would like to explore the question of whether this “dual use” is actually worthwhile – or whether it remains primarily a technical promise. PVT is still a niche technology: high costs, missing standards and limited practical experience are slowing its spread.

This article helps to realistically assess the technology for use in residential buildings – technically, economically and practically. It is based on current scientific publications and my experience as an energy consultant. In addition, we conducted a market survey on acquisition costs and previous experience values.

What is a PVT module?

A PVT module is a hybrid (mixed-use) solar collector that combines photovoltaics (PV) and solar thermal energy (T) in one housing. It therefore generates solar power and heat at the same time.

How does PVT work?

PVT works by attaching a thermal collector to the rear side of the PV module. While the solar cells generate electricity, the collector absorbs solar heat and feeds it into a heat circuit. The heat absorbed from the sun and outdoor air is typically supplied to a heating heat pump.

What types are there?

The photovoltaic top side of PVT modules always corresponds to a classic PV module. The differences lie only in the types of thermal collectors located on the underside.

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  Unglazed PVT collectors: A liquid absorber without an additional cover or insulation is installed beneath the PV module. A liquid absorber is a pipe system through which a mixture of water and antifreeze flows, absorbing heat in the process – similar to a garden hose that warms up in the sun. Unglazed collectors are usually combined with heat pumps. Heat pumps can operate well with the rather low source temperatures reached in unglazed PVT collectors.

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  Glazed PVT collectors: This design is similar to a classic flat-plate solar thermal collector. An additional glass pane is located above the PV cells, which, together with an air layer, reduces heat loss. Beneath the PV cells is a liquid-filled absorber that absorbs the heat. Thanks to the cover and thermal insulation on the rear side, glazed collectors reach higher usable temperatures and can therefore be used directly for domestic hot water preparation, like classic solar thermal collectors.

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  PVT air collectors: Here, air serves as the heat transfer medium, flowing through an air duct on the rear side of the PV module and warming up in the process. The heat gained can be used for supply air preheating, drying or as a heat source for a heat pump.

By far the most widespread in Germany are PVT collectors with unglazed solar thermal technology. They account for around 95 % of the installed area [AEE INTEC, 2025]. Glazed PVT collectors are used much less frequently (4.5 %). Air collectors (0.28 %), on the other hand, are hardly widespread and play no role in residential buildings.

Internationally, a similar picture emerges: in most countries, unglazed systems also dominate. France is an exception – there, PVT systems with air collectors are predominantly installed.

What advantages does PVT have over photovoltaics or solar thermal energy?

The advantage of PVT modules lies in their dual use: they generate electricity and heat at the same time on the same surface. This allows limited roof space to be used twice and significantly increases the energy yield.

Cooling the PV module also increases the efficiency of electricity production. Manufacturers cite additional yields of five to 20 percent for this. In a personal technical discussion, one PVT manufacturer classified the sometimes cited additional yields of up to 20 percent as short-term daily peaks. For the annual average, the manufacturer states realistic additional yields of around 5 percent. This difference is crucial for the cost-effectiveness assessment, since annual yields – not daily peaks – determine the amortization of a PVT system.

When PVT collectors are combined with a brine/water heat pump installed inside the house, a silent system is created – entirely without the noise of an outdoor heat pump unit.

Can a heat pump be operated with PVT modules?

Yes, heat pumps can be combined with PVT modules. The combination of PVT technology and heat pump is now even the predominant application – technically, the concept works, but economically it is still controversial.

PVT modules are sometimes advertised as a replacement for geothermal probes or outdoor air heat exchangers. The liquid heated in the PVT modules can be fed into a brine/water heat pump as solar environmental heat. Due to the higher heat source temperature during solar irradiation, the heat pump works more efficiently compared to air-to-water heat pumps and generates more heat per unit of electricity used. The extent of this efficiency increase has so far only been studied for individual systems; field studies are still lacking.

PVT modules can replace geothermal probes or outdoor units for using environmental heat for a heat pump. For an economic assessment, however, it is crucial whether this efficiency increase compared to air-to-water heat pumps justifies the additional costs compared with conventional outdoor air heat exchangers. This is exactly where the dilemma of many innovative heating concepts becomes apparent: the idea is convincing, but a reliable data basis is still lacking.

Is PVT an alternative to geothermal probes?

PVT modules can technically replace geothermal probes, but they are only partially equivalent – especially in winter, their heat output drops significantly. In a cost comparison, however, PVT modules are at least comparable with geothermal probes, and often probably even have an advantage.

If the construction of a ground heat exchanger is not possible, PVT modules can serve as an alternative heat source.

According to several providers, PVT modules are said to be able to completely replace ground heat exchangers. In my professional assessment, however, this has not always been proven beyond doubt so far: the available data is not yet sufficient here. At present, one can only state that PVT modules apparently work well in milder regions with standard outdoor temperatures down to -10°C.

Does PVT with a heat pump make sense for replacing outdoor units?

PVT modules can replace the outdoor unit of an air-to-water heat pump. Instead of the air-to-water heat pump, a brine/water heat pump is supplied with heat by the PVT system. The heat pump requires less electricity during solar irradiation, meaning it works more efficiently on sunny days than an outdoor air heat exchanger and is also completely silent.

The combination of PVT and a brine/water heat pump would be economically sensible if the electricity savings during heat pump operation, together with the photovoltaic yield, offset the additional costs of the PVT system.

How useful are PVT modules as a heat source for heat pumps?

PVT modules are suitable as a heat source for heat pumps – their advantages are particularly evident in summer and at mild temperatures.

Ground heat exchangers, by contrast, also provide comparatively high and steady source temperatures during the winter months. In contrast, the temperature at PVT modules on days with little sun is usually in the range of the outdoor air. In phases with little sun and temperatures below zero degrees Celsius, there is therefore, in my opinion, no significant efficiency advantage over an air-to-water heat pump.

On sunny days and in the summer months, the roof surface becomes significantly warmer than the ambient air. In the warm season, PVT modules therefore have advantages over ground and air heat exchangers. They are particularly suitable for applications with increased heat demand in summer, such as domestic hot water preparation or process heat.

For classic residential buildings, however, this is not a typical use case. Due to the high system complexity, the use of PVT modules in combination with heat pumps for heat generation in residential buildings can therefore currently only be recommended in milder climate regions with standard outdoor temperatures down to a maximum of -10°C.

Assessment of PVT technology and current experience

Independent practical experience with PVT systems is still rare because the technology is not yet very widespread. This makes it difficult to assess the efficiency, durability and maintenance requirements of the technology.

What experience is there so far with PVT systems?

The available information comes predominantly from manufacturers or projects such as ‘integraTE’. This project is intended to support the market launch of the technology. Fewer than five experience reports can be found in forums.

I contacted numerous PVT operators, but despite support from researchers and manufacturers, I was only able to conduct two personal interviews. One manufacturer insisted on presenting a new system to me. In my view, only systems that have already been operated for several years are meaningful, since technical weaknesses usually only become visible after a certain operating period. I therefore took a closer look at two systems that have already been in operation for more than five years. One of the two systems can also be seen in my YouTube video on PVT (not yet published at the moment).

Field report: PVT system with heat pump in a two-family house near Ulm

I was very pleased that Markus Schmidt shared his experience with us. As part of the energy modernization of a two-family house built in 1972 near Ulm, he had a PVT system with heat pump installed in 2018. Schmidt is managing director of the PVT manufacturer EVO Deutschland GmbH. His system was scientifically measured by Fraunhofer ISE.

Technical data of the system:

• PVT modules: 52 EVO TEHA-4 modules (88 m²)
  – electrical output: 15.6 kWp
  – thermal output: 56.3 kWp
• Heat pump: Viessmann Vitocal 300-G (13 kW thermal output)
• Heated area: 411 m² + pool
• Annual final heat energy demand: 36 kWh/(m²a) (KfW70 house)

Operating experience:

• A gas boiler is available as backup, but is not used.
• The seasonal performance factor of the heat pump was between 3.72 and 3.88 over the last four years. That is a good, solid value.
• Additional PV modules with roughly the same electrical output are located on the flat roof; the PVT system generates around 3 % more electricity.
• A hose leak occurred once – probably due to an installation error. It was noticed because the pressure gauge installed in the basement showed low pressure.
• During prolonged frost, icing occurred, but it did not cause any impairment or further damage.
• Schmidt could not report any higher maintenance effort compared with photovoltaics.

Despite the company-related perspective, the example provides valuable technical insights. It shows that combined PVT systems with heat pumps can also operate reliably and efficiently in existing buildings – especially when they are planned and installed professionally.

Field report: PVT system with heat pump in a single-family house in Alkmaar (NL)

Another valuable experience was my visit to Alkmaar to see Gijs van Wijkin. Gijs installed his Triple Solar system in 2017. The reasons for choosing a system from Triple Solar were rather coincidental for Gijs. He himself was and is active in energy consulting and knew Triple Solar through his work. In addition, Triple Solar’s company headquarters are located not far from his home.

At the time, it was one of the first systems of the generation that is still current today. This generation was specifically designed for operation in connection with heating heat pumps, i.e. for the winter situation.

Back then, the system was still supplied with a Nibe heat pump. This was not yet optimally matched to the overall system. The options for optimization were also still limited because a heat pump from a third-party manufacturer was used.

Despite the pioneering character of the system, Gijs would choose a PVT system again today. Based on his assessment and experience, PVT is a safe technology without significant maintenance requirements. To date, the system has operated practically without faults.

In addition to Gijs’s system, I was also able to inspect a newer system that is already operated with one of the heat pumps designed by Triple Solar itself.

The spread of PVT modules is limited

The rarity of experience reports can be explained by the limited spread:

At the beginning of 2024, according to the German Environment Agency, around 256.5 million m² of roof area in Germany was covered with PV modules, while PVT modules accounted for only 184,869 square meters – less than one per mille [AEE INTEC, 2025]. This illustrates that PVT has so far played only a niche role in the market.

Nevertheless, Germany recorded the world’s largest increase in PVT systems in 2024: 11.4 MW (thermal), according to the International Energy Agency – assuming the collected figures are correct. One manufacturer also reports that interest is increasing particularly in the apartment building sector.

Overall, it is clear that despite growing attention, the technology is still in an early market launch phase.

Advantages and disadvantages of PVT modules

PVT modules combine electricity and heat generation on the same surface and increase area efficiency, but they are technically complex and still cost-intensive.

The advantages of PVT collectors are particularly relevant for terraced houses. There, roof space is scarce, and there is often no space for an outdoor unit of a heat pump.

Advantages

• Dual benefit: Generate heat and electricity simultaneously on the same surface.
• High area efficiency: Total efficiency per m² is significantly higher than that of photovoltaic or solar thermal systems.
• Higher PV yield: Cooling the solar cells increases electrical output, especially in summer.
• Climate advantage with a large system: Sufficiently large PVT systems can be more climate-friendly than the combination of photovoltaics and an air-source heat pump, since less electricity is required for heat generation.

Disadvantages

• High investment costs: More expensive to purchase than pure photovoltaic or solar thermal systems.
• Complex planning and maintenance: Installation and system integration are more involved.
• Technical conflict of objectives: Modules can only be optimized for heat, electricity or a compromise.
• Limited market and specialist expertise: There are still few planners and installers with practical PVT experience.

Are there independent tests of PVT collectors?

There are still no independent tests that enable a direct comparison of PVT collectors. Instead, measurement data from real operation are available for individual systems and are scientifically evaluated, supplemented by simulations and laboratory investigations.

A binding test standard specifically for PVT collectors is still pending, which makes the practical comparability of manufacturer specifications considerably more difficult. A systematic literature review on the residential building sector also points out that there have so far been too few experimental studies with sufficiently long runtimes [University of Portsmouth – PVT Review, 2021].

PVT system: acquisition costs compared with photovoltaics

PVT modules currently cost about four to five times as much as photovoltaic modules, but in addition to electrical energy they also generate three to four times as much heat. Without subsidies, they are considered economically unattractive. In Germany, they are subsidized in 2025 as part of a heat pump system through the Federal Funding for Efficient Buildings. Since BEG funding is capped, only part of the acquisition costs for the PVT system that are additional to the heat pump can be subsidized.

A direct cost comparison with photovoltaics alone falls short because the heat yield is not taken into account. A fair comparison would be to compare PVT with a combination of photovoltaics and solar thermal energy with the same total energy – a system that is rarely implemented in practice. More relevant, therefore, are comparisons between PVT systems and photovoltaic systems, each combined with heat pumps.

How expensive are PVT modules compared with PV modules?

According to a cost survey by the integraTE XL project, unglazed PVT collectors with a simple absorber suitable for heat pumps cost an average of €386 net per square meter. Models with a large-area ambient air heat exchanger are around €100 more expensive. For comparison: photovoltaic modules currently cost end customers €80 – 106 / m² [own conversion based on co2online, as of 02/2024].

Depending on the design, PVT modules are therefore around four to five times more expensive than PV modules, but they also supply usable thermal energy.

In addition to the modules, the following components are required for a complete PVT system:

• Substructure
• Inverter & electrical accessories (BoS)
• Hydraulics (pipes/fittings/pumps/heat exchangers)
• Buffer storage tank, if not already present
• Labor time

For designing a PVT system, a guideline value of 3.0 m² of module area per kW of heating capacity can be used – in colder regions such as the Alps or the Erzgebirge, it is about 4.0 m² per kW. The required module area therefore results directly from the required heating capacity.

What does a PVT system cost in Germany?

In my own market survey among several PVT providers, most did not name flat-rate prices and referred to individual planning. I often hear such answers in building-related topics when manufacturers feel uncomfortable giving a number. My impression: the “individuality of buildings” often serves as a convenient explanation. One provider at least named a rough complete price for modules, support system, storage tank and heat pump including installation.

Accordingly, a PVT system with heat pump for a typical single-family house in Germany currently costs around 45,000 (small terraced house) to 65,000 euros.

For comparison: A PV system with air-to-water heat pump can already be purchased from around 37,000 euros. Of this, an 8 to 10 kWp photovoltaic system without battery storage costs an average of around 17,000 euros (Verbraucherzentrale, as of May 2025). The air-to-water heat pump costs around 35,000 euros without subsidies (Verbraucherzentrale Rheinland-Pfalz, as of May 2025). This means that the combination of PV and air-to-water heat pump is at least in the same order of magnitude as a PVT system with heat pump.

The available figures suggest that PVT technology can at least be an economic option when looking for an overall concept for PV and a heating heat pump. However, these responses also show that market prices for PVT systems are currently still quite opaque. For concrete offers, one would need to arrange on-site appointments with several manufacturers and obtain specific quotations.

Conclusion: When is a PVT system worthwhile?

PVT is currently particularly interesting for owners who are looking for a heat pump that works especially quietly or where limited roof space is to be used twice.

From an energy perspective, the concept is convincing – electricity and heat from the same surface are technically possible and make climatic sense. However, the system is more complex and therefore possibly somewhat more susceptible to planning and execution errors. The lack of standardization also makes it more difficult to select suitable manufacturers and products. Anyone who wants to install PVT today needs one of the few experienced specialist companies – and trust in its competence. Some manufacturers therefore work very closely with selected specialist companies.

A clear additional benefit is the fact that no outdoor unit is needed, as with an air-to-water heat pump. This offers two advantages: first, without an outdoor unit, no installation location is needed. The heat exchanger is located on the roof in a space-saving way. Second, PVT is completely silent outdoors. PVT technology is therefore a good option especially where space is tight, as is the case, for example, in terraced housing estates or also in apartment building districts.

However, for those who have space and for whom the noise emissions of an outdoor unit of an air-to-water heat pump are not a problem, a PVT system offers no compelling advantages over the much more widespread air-to-water heat pump. For that, the energy efficiency advantage over conventional outdoor air heat exchangers is too small.

Whether PVT technology emerges from this niche depends on how much system costs can be reduced and whether the funding framework remains stable.

My advice: anyone considering PVT should keep a close eye on the technical development. Ideally, obtain several concrete offers for both variants in order to create an objective decision-making basis tailored to your own house.

Featured image:

• Installation of PVT modules on a flat roof (Image: EVO Deutschland)