PVT Systems: Questions About Planning, Costs and Subsidies
There are many factors to consider when planning a PVT heating system. This section provides answers to frequently asked questions on topics such as costs, subsidies, system design, and amortization. Whether it’s for a single-family home or a large-scale PVT project, and whether the system is monovalent or bivalent—here you’ll find the key information you need. This section is updated and supplemented on an ongoing basis. We reserve the right to make changes accordingly. All information is without guarantee.
PVT systems are considered an accompanying measure for heat pumps and are therefore eligible for subsidies.
The German Federal Subsidy for Efficient Buildings – Individual Measures (BEG-EM) provides funding rates ranging from 30% to 70% and applies to both residential and non-residential buildings. However, there are subsidy caps in place, and the exact level of funding depends on the specifics of each project. Applications for PVT subsidies are submitted through the KfW Bank. Our specialist partners are happy to provide advice on this process.
For large-scale industrial projects and cold local heating networks, the Federal Funding for Efficient Heating Networks (BEW) is available. This program offers funding rates of up to 50%. Please feel free to contact us – we will connect you with a qualified specialist, HVAC planner, or energy consultant to support your project.
Contrary to common belief, PVT systems do not fall under the category of solar thermal energy.
From a legal point of view, a photovoltaic-thermal (PVT) system is considered an accompanying measure to a brine heat pump. If you apply for a brine heat pump funding, the corresponding funding rate is automatically extended to the associated PVT system.
According to the BEG-EM funding scheme, sole PV modules are not eligible for funding. However, as PVT is considered an accompanying measure for brine heat pumps, the thermal side of our modules can be subsidized on a pro rata basis. To determine this, EUR 1,500 per kWp of electrical output is deducted from the purchase price of the entire system. The individual subsidy rate is calculated from the difference; however, the maximum amount eligible for subsidy is limited to 30,000 euros – at least in Germany.
An example:
Assuming the purchase price of a PVT heating system (incl. modules, heat pump, hydraulics and installation) is 45,000 euros gross. The electrical output of the modules is 8.6 kWp. To determine the non-eligible PV share, we calculate 8.6 kWp * 1,500 euros and end up with 12,900 euros. We now deduct this amount from the total costs: 45,000 euros – 12,900 euros = 32,100 euros.
As the maximum eligible amount is capped at 30,000 euros, this is 15,000 euros for a 50% subsidy. These 15,000 euros are now deducted from the total costs of the PVT heating system: 45,000 euros – 15,000 euros = 30,000 euros after subsidy.
For residential properties, the BEG-EM program offers heating system replacement subsidies of up to 70%.
This applies, for example, to the installation of a sustainable heating system or a connection to a building or district heating network. The responsible KfW Bank considers investment costs of up to €30,000 for single-family homes; these are correspondingly higher for multi-family homes. On the KfW Bank’s website, you can find detailed information about who is eligible to apply and the requirements your property must meet to qualify for funding.
Once your funding application has been approved, the allocated amount is bindingly reserved for you. This ensures that the KfW can disburse the approved funds once the system has been installed.
If you wish, our partner network will be happy to advise you on how to secure the maximum possible funding for your new PVT heating system. Please contact a Sunmaxx partner in your region for assistance.
Currently, only the transition from fossil-based to renewable heating systems is eligible for funding. To define the scope of your project costs and identify potential (often hidden) funding opportunities, it is advisable to consult an energy advisor or a Sunmaxx specialist partner. In many cases, there are regional subsidy programs that apply to specific federal states – or even just to individual districts or cities.
Decarbonization is a broad and complex field, and funding may also be available for new construction projects. It is essential to pay close attention to local regulations, deadlines, and formal requirements. An energy consultation is the best point of contact to receive comprehensive information about all relevant funding opportunities.
The current exemption from VAT also applies to PVT modules – not just to conventional PV. This is particularly advantageous, as our technology generates both electricity and heat at the same time. We combine the best of both worlds: eligibility for solar thermal subsidies and the VAT exemption granted to photovoltaic systems. The exemption covers all system components (e.g. mounting structures, hydraulic components) as well as the associated installation work.
Our modules are not sold to private customers. For business customers, we are happy to provide a tailored offer. Please contact our sales team or reach out to us by phone at +49 35205 69401-0 or via email at office@sunmaxx-pvt.com.
For large-scale projects – such as cold local heating networks, hospitals, schools, swimming pools, and commercial or industrial applications with sufficient installation area – you can calculate with a price of approximately 400 euros per m² (or around 2,000 euros per kWp) for the complete PVT installation. This price includes PVT modules, mounting structures, piping up to the roof edge, inverter, and installation services.
For single-family homes, a full system – including a compatible ground-source heat pump – can typically be offered starting at 45,000 euros gross. Funding subsidies are then deducted from this amount. However, actual costs depend heavily on the specific project and local conditions. In special cases, the estimated price may be significantly exceeded. We therefore recommend contacting a Sunmaxx partner in your region to receive a customized offer tailored to your needs.
Sunmaxx is a manufacturer of hybrid modules, but does not offer direct sales. We only make exceptions for very large purchase quantities. Your first point of contact for the purchase of Sunmaxx modules are our wholesale partners Wagner Solar and Rehl Energy. For private and single-family house projects, please contact a Sunmaxx partner in your region to receive an individual offer for a PVT system including installation costs. Direct sales to private customers is not possible.
Investing in a PVT heating system is a smart decision in almost every case. With the rapidly rising costs of fossil fuels (due to CO₂ pricing), a PVT heat pump almost always pays off – especially when using Sunmaxx modules, as we produce the most powerful and cost-effective hybrid modules on the market.
For large-scale PVT systems (e.g. district heating networks or industrial applications), the levelized cost of heat typically ranges between 6 and 8 euro cents per kilowatt-hour, and in some cases even falls below 5 euro cents per kWh. This already puts us below the current cost of natural gas.
In the residential sector, a PVT heating system also enables very low heat generation costs of less than 10 euro cents per kWh.
This makes a PVT heat pump a highly worthwhile investment, offering the potential to significantly reduce operating and ancillary costs in the long term.
The payback period for a Sunmaxx PVT system varies from project to project. Key factors include the size of the system and its intended use (e.g. private vs. industrial applications), as well as local conditions. For our current large-scale PVT projects, we typically calculate a payback period of 5 to 8 years – based on a typical system lifetime of 30 years or more.
PVT systems are suitable for almost every type of buildings – from classic single-family houses to multi-family homes and large residential complexes.
It makes no difference whether the house is detached or part of a row. In fact, PVT systems are particularly ideal in densely built-up areas, as they operate completely silently – unlike, for example, air-to-water heat pumps – eliminating concerns related to noise emission regulations.
The shape and orientation of the roof also play only a minor role.
What’s more important is that the building has sufficient space to accommodate a brine heat pump – for example, in the basement or utility room. Underfloor heating is not a requirement for a PVT system. With the right heat pump, existing wall-mounted radiators can continue to be used without any concerns.
Your local Sunmaxx partner will be happy to explain which measures should be considered as part of a PVT system installation during a non-binding consultation.
PVT systems generate what’s known as low-temperature heat. They achieve optimal efficiency when the supplied thermal energy can be utilized to the greatest extent possible. Good insulation is therefore not essential, but of course helpful.
For flat roofs, we recommend an east-west mounting of the modules with a tilt angle of 10 to 15°. In the case of pitched or sloped roofs, the existing roof angle should be used.
In general, our system supports nearly all tilt angles – from 0° on flat roofs to 90° for PVT façade installations.
Yes, green roofs are generally compatible with our modules and can be taken into account during the planning phase. The only important requirement is to maintain a clearance of approximately 50 cm between the modules and the vegetation to avoid shading and/or disruptions to the rear ventilation of the system. Corresponding concepts are available and have already been implemented.
No, PVT systems using Sunmaxx hybrid modules operate completely silent. This is a major advantage over air-to-water heat pumps, whose outdoor units are increasingly restricted in various areas due to noise emissions.
In contrast, PVT acts as a silent heat source on the roof, supplying both electricity and source heat for brine heat pumps.
Unlike air-to-water systems, brine heat pumps do not require an outdoor unit and are installed inside the building – typically in the basement or a technical room.
As a result, they are not subject to local noise emission regulations. Additionally, brine heat pumps operate almost completely noiseless, as they do not rely on fans.
If you are interested in installing a private PVT system, feel free to contact us by phone or email – or reach out directly to our partner network. Upon request, we will gladly connect you with a qualified installation company in your region. To help us in assisting you more efficiently, it would be helpful to initially provide us with some basic information about your project, such as:
- Region or specific address
- Year of construction of the building
- Energy efficiency class (if known)
- Annual heat demand in kWh (if known)
- Current heating system
- Roof type (flat or pitched)
- Contact details (phone and email)
Or would you rather like to work with your own heating installer or solar technician? You’re always welcome to recommend Sunmaxx to them. After completing a one-day training session, the installer will be fully familiar with our system and qualified to install a PVT system with Sunmaxx hybrid modules on your roof.
This depends on the configuration of the PVT heating system. As a general estimate, you can expect an initial investment of at least 45,000 euros, minus applicable subsidies. Replacing radiators is not necessarily required; modern brine heat pump systems can provide good to excellent room heating even with existing wall-mounted radiators.
In the case of very old buildings – for example, those with cast iron radiators – we would recommend carrying out some modernization measures before investing in a PVT system. Installing new insulation, for instance, significantly improves the system’s efficiency, which will have a noticeable impact on ongoing electricity costs.
Yes, a PVT system is always tailored to the building and its individual energy ndemands – just like any other heating solution. For single-family home projects, our partner network is your primary point of contact. For larger project inquiries, please contact us directly via email at office@sunmaxx-pvt.com.
Sunmaxx is integrated into all commonly used simulation software tools, such as Polysun, nPro, and PVSol*. Please note that PVSol* only covers the electrical (PV) side of the system, but it is very useful for precise roof layout simulations.
We are also in close collaboration with providers such as Hottgenroth. Whether you’re planning a single-family home, an industrial facility, or a municipal heating project—our modules can be represented on both the electrical and thermal sides in various planning tools, enabling year-round system simulations.
Monovalent PVT systems are heating solutions where our hybrid modules serve as sole heat source for the brine heat pump. For single-family homes, this is a common standard and, in the long run, more cost-effective than operating an air-to-water heat pump with PV. At the same time, monovalent PVT systems require a lower initial investment compared to, for example, a geothermal heating system.
Monovalent PVT systems are a solution in areas where regulations prohibit the installation of other (renewable) heating systems. This may apply, for instance, to geothermal probes or ground collectors in water protection areas, or to air-source heat pumps in densely built-up regions where noise emissions are a concern. As a backup, monovalent systems often include an electric heating element within the heat pump, in case the heat pump should fail.
As a general rule of thumb, we recommend allocating at least 2 Sunmaxx PVT modules or 4 m² of PVT area per kW of the brine heat pump’s heating output. One Sunmaxx module corresponds to 2 m² of PVT surface area. This is the minimum required to ensure an adequate heat supply. If the budget allows, a larger PVT system can always be considered. This will increase the efficiency (COP) of the brine heat pump, resulting in lower long-term electricity and heating expenses.
Bivalent PVT systems generate heat in combination with additional energy sources (and storage solutions). These can include ground collectors and geothermal probes, as well as ice or water storage systems. Hybrid heating systems combining PVT, a brine heat pump, and a gas boiler as backup are also possible.
Bivalent PVT systems are primarily used in projects where the available roof space is insufficient to cover the full heating demand. This applies to multi-family homes and residential complexes, as well as municipal heating networks or industrial applications involving process heat. Due to its ability to produce both electricity and heat at the same time, PVT is a valuable solution for almosty any type of project.
In cases of a full transition to renewable heating (and cooling) – for example, through a combination of PVT and geothermal energy – hybrid modules enable significant savings on initial geothermal system investment costs. This is possible because the excess heat generated by the PVT modules in summer can be stored in the ground. Geothermal probes can even be regenerated this way, allowing a theoretically unlimited operation.
An important side benefit: thanks to the regeneration, less geothermal surface area or fewer drilling meters are needed. Since these are typically among the most expensive elements of switching to renewable heating systems, PVT can reduce overall project costs significantly – in some cases even by up to 75%. Bivalent systems currently represent the most efficient heating solution, with Seasonal Performance Factors (SPF) of over 6.
For the design of bivalent PVT systems, we recommend first simulating the setup using professional planning software such as nPro or Polysun. Upon request and for a corresponding fee, our team will be happy to prepare a tailored concept for you. Please contact us via email at office@sunmaxx-pvt.com for further details.
Under full solar irradiation, a Sunmaxx hybrid module of type PX-1 achieves a thermal output of 1,200 W per module, or 600 W/m² of PVT surface area.
If there is no solar irradiation (e.g. at night), meaning the module can only utilize anergy (i.e. ambient thermal energy), the thermal output still reaches 100 to 300 W per module, or 50 to 150 W/m² of PVT surface, depending on local conditions.
Cooling:
With active cooling (via heat pump), a thermal output of at least 200 W per module, or 100 to 200 W/m² PVT surface, can be achieved. When passive cooling (without heat pump, e.g. at night), Sunmaxx modules cool at a thermal output of approximately 100 W per module, or 50 to 100 W/m² PVT surface.
The thermal yields depend heavily on how the system is integrated into the complete energy setup. Accurate figures can only be provided through simulations using software tools such as Polysun or nPro. However, the following values may serve as general guidelines, based on climatic conditions in Germany and Central Europe:
- Monovalent Sunmaxx PVT system: 400 to 500 kWh/m² annually
- Bivalent Sunmaxx PVT system with ground probe (field) regeneration: 350 to 450 kWh/m² annually
- Bivalent Sunmaxx PVT system with ice storage regeneration: 400 to 800 kWh/m² annually
The overall system planning is usually carried out by the technical building services or energy planning company that was initially commissioned with the project. In the case of single-family house projects, this is usually the installation company.
We have an extensive network of architecture, TGA and energy planning offices. Please send us an e-mail to office@sunmaxx-pvt.com. We will be happy to put you in touch with a suitable partner.
Right now, we are not aware of any agri-PVT systems – neither from Sunmaxx nor from any other PVT manufacturer. However, we are already in talks with specialist planners about several projects. From a technical point of view, a design scenario of this kind with PVT is of course possible.
Applications involving ceramic storage are generally not relevant for PVT systems. Photovoltaic-thermal modules generate and store heat on a low-temperature level. With brine heat pumps, these temperatures can be raised to around 150 to 200 °C. Even then, we’re still far from reaching that high target temperatures. This is one of the few applications for which PVT technology is genuinely not suitable.
The levelized cost of heat depends heavily on the size of the system, the specific application, and the location. An example calculation might look like this:
With an investment of 2,000,000 euros (excluding external financing, with subsidies already deducted) and a thermal output of 1.5 GWh per year over 30 years, the calculation is as follows:
1.5 GWh * 30 years = 45 GWh = 45,000 MWh = 45,000,000 kWh. This results in 2,000,000 euros / 45,000,000 kWh = 4.4 €ct/kWh.
Add O&M costs: 0.5% of the investment per year = 10,000 euros annually. Over 30 years, this makes: 10,000 euros * 30 = 300,000 euros (not accounting for inflation) = 300,000 euros / 45,000,000 kWh = 0.7 €ct/kWh.
Grid electricity must also be taken into account. As we often achieve so-called annual performance figures of over 6 for heating networks and industrial projects (i.e. 6 kWh of heat are generated from 1 kWh of electricity), this can be divided by the annual performance figure. In this specific case, 18 €ct (net industrial electricity price) divided by 6 = 3 €ct/kWh. This results in a total of 4.4 + 0.7 + 3 €ct/kWh = 8.1 €ct/kWh..
If external financing is used, investment costs would increase slightly depending on the interest rate – however, this impact is typically marginal.