Heat Pump · Heating and Cooling

This is only possible in specific applications, such as swimming pool heating. A PVT system generates heat at a so-called low-temperature level, similar to the ambient temperature. This is usually not sufficient to directly heat domestic hot water. At this point, a brine-to-water heat pump comes into play: it absorbs the low-temperature energy and releases it at a higher temperature. That way, both space heating and domestic hot water are provided. Swimming pools are an exception, as conventional heating and hot water preparation are not required. Here, a PVT system can be used to warm up the pool water directly. The only component that is needed is a suitable heat exchanger.

PVT modules serve as a direct source of electricity and heat for brine-to-water heat pumps. The system operates using low-temperature heat and is fundamentally similar to the operating principle of an air-to-water heat pump with PV support. However, unlike air-source systems, a PVT system captures heat not only from the ambient air but also from solar radiation. This makes Sunmaxx modules particularly efficient.

Our technology harnesses the energy received on the roof with maximum efficiency. A heat exchanger on the rear side of the module transfers the heat from both the PV surface and the ambient air to a heat transfer fluid. This fluid circulates within a hydraulic system between the PVT installation and the brine heat pump, supplying the pump with the required source heat.

It is important to note that “heat” is a relative term. Even a winter day with an outside temperature of -10 °C and no solar radiation still provides usable heat that the Sunmaxx PVT system delivers to the heat pump. What matters most is selecting the appropriate heat pump manufacturer or model for each individual project. For monovalent systems (i.e., PVT as the sole heat source for the brine heat pump), we recommend using a brine heat pump that can operate with source inlet temperatures of -15 °C or below. For additional security during extremely cold weather, an electric heating element is advisable.

In many cases – especially in larger projects – multiple heat sources (bivalent or multivalent systems) are used. These can include, for example, a borehole field, an ice storage system, or a gas boiler as a backup. In such scenarios, any standard brine-to-water heat pump can be used. The bivalence point (e.g., 5 °C) determines when the system switches from one source to another.

A PVT system always serves as a direct source of electricity and heat for brine-to-water heat pumps (with the exception of swimming pool applications). The primary factor is the heat demand of the building and its intended use. The brine-to-water heat pump must be sized according to this heat demand. In turn, the size of the PVT system is determined by the size or heating capacity of the heat pump.
As a general rule of thumb: 1 kW of heating capacity requires at least 2 Sunmaxx PVT modules or approximately 4 m² of PVT surface area. For residential and single-family home projects, your local Sunmaxx partner is your main point of contact for planning and installation. For larger projects, we recommend using suitable simulation software such as nPro or Polysun.

In new buildings, heat pumps are increasingly becoming the heating system of choice – ideally in combination with a PVT system. After all, this combination represents one of the most efficient heating solutions on the market.
However, switching to a PVT system with a brine-to-water heat pump is also worthwhile for existing buildings. Underfloor heating is not strictly necessary; good heating performance can also be achieved with wall-mounted radiators that are already existing. A solid insulation further increases the overall system efficiency.
In principle, whenever a new installation is planned or a switch to a heating system with PVT technology is considered, the specific conditions of the building and site should always be carefully assessed. We recommend contacting a qualified Sunmaxx partner in your region. They can provide tailored advice and create a customized offer for your project.

This is possible, but not recommended for every system. If a brine-water heat pump with a geothermal source (e.g. geothermal probes or collectors) is already in place, the heating system can be expanded to include a PVT system without significant additional expense. In contrast, this is not possible if an air-to-water heat pump was chosen as a heating system.

We mainly see PVT as a financially attractive, climate-friendly, and efficient replacement for fossil fuel heating systems, combining nearly all the advantages of renewable technologies in one single solution.

No, in most cases it is not necessary to replace existing wall-mounted radiators. While underfloor heating systems (so-called low-temperature heating systems) operate more efficiently with PVT, effective room heating can still be achieved using existing radiators. Modern brine heat pumps are fully capable of delivering the required performance.
Another option is the installation of a ceiling heating system, provided the spatial conditions allow it. This approach can avoid the need to remove the entire floor and replace the screed during a heating system renovation.

In principle, yes – given the fact that it is a brine-to-water heat pump. Our PVT modules are not compatible with air-to-water heat pumps, as these systems extract their source heat exclusively from the ambient air. This requires a special outdoor unit with fans, which is not needed for PVT systems.

If you choose a PVT heating system consisting of hybrid modules and a brine-to-water heat pump, Sunmaxx offers maximum flexibility. Our system is open and compatible with all common manufacturers and brands of brine heat pumps – especially in bivalent configurations. For monovalent systems, we recommend selecting a heat pump that can handle source inlet temperatures of -15 °C or below.

Yes, operating PVT modules in combination with a brine-to-water heat pump is the most efficient and cost-effective method. The only exceptions are special applications, such as the heating of swimming pools and basins.
One key advantage of PVT is that it does not generate temperatures as high as those of traditional solar thermal systems. Otherwise, a brine heat pump would not be able to operate with the system.

Sunmaxx is an open system. This means that all standard brine-to-water heat pumps and their respective manufacturers or brands are compatible with our PVT modules. This applies especially to bivalent systems, e.g. PVT in combination with ground probes, ground collectors, or an ice storage system.

For monovalent applications, we recommend a model that can handle source inlet temperatures of -15 °C or below. Sunmaxx maintains partnerships with many heat pump manufacturers whose systems have been tested and optimized for use with our hybrid modules. Upon request, we are happy to provide you with an overview.

A PVT heating system consists of two components: a PVT installation and a brine-to-water heat pump. The PVT system is installed on the roof, while the brine heat pump is located indoors. In addition to generating electricity, the PVT installation also provides the source heat required for operating the brine heat pump. In contrast, a system combining an air-to-water heat pump with PV derives its heat exclusively from the ambient air. This requires an additional outdoor unit with fans for air exchange – making it a three-component system.

In direct comparison, a PVT heating system offers significantly more advantages. It requires no fans, as the heat exchange takes place entirely through the module surface, rear ventilation, and natural convection. As a result, a PVT heating system operates completely silent. It also draws its source heat not only from the ambient air but also from solar radiation. This enables higher source inlet temperatures, allowing the system to run far more efficiently over the long term – with seasonal performance factors (SPF) between 4 and 4.5, compared to around 3 for air-to-water heat pumps. The outcome: reduced electricity consumption and significantly lower operating costs in the long-term.

In summary, a PVT heating system offers the following advantages over a combination of air-to-water heat pump and PV:

• Two components instead of three – reduced planning complexity
• Aesthetic installation – no outdoor unit required
• Silent operation – ideal for noise-restricted areas
• Sustainable – electricity and heat from one single system
• Efficient – lower power consumption thanks to high efficiency
• Low maintenance – gentle operation with longer service life
• Long-term savings – lower operating costs in the long-term

In monovalent systems (i.e., PVT as sole heat source for the brine-to-water heat pump), at least 4 m² of PVT surface area (equivalent to 2 Sunmaxx PVT modules) are required per kW of heating capacity of the heat pump*. The basic requirement is that there is sufficient roof space available for the PVT system. Therefore, monovalent systems are primarily suitable for single-family homes with a manageable heating demand. It is also important to ensure that the selected brine-to-water heat pump can operate with a source inlet temperature of -15 °C or below.

An example:
For a small single-family home project with an 8 kW brine-to-water heat pump, approximately 16 Sunmaxx PVT modules or 32 m² of PVT surface area would be required. With this configuration, the building would be well equipped for the winter. A larger system size can be beneficial for increasing the overall efficiency of the heating system.

*Depending on the location and structural conditions, these specifications may vary. We recommend to always consult a Sunmaxx partner to ensure that the PVT heating system is perfectly tailored to your individual heating needs.

In winter, there is relatively more ambient heat than radiant heat available. When there is no solar radiation, the maximum source heat that can be gained from the roof corresponds to the ambient temperature. However, as soon as sunlight hits the module surface, the PVT system automatically gains advantages over a comparable heating system using an air-to-water heat pump (and PV). Due to solar radiation, the module heats up and can supply source temperatures of up to 20 °C, even in winter. Nevertheless, especially in monovalent systems, it is advisable to have an electric heating element as a backup. An old gas boiler or pellet stove can also be used as additional support.

For the design of a monovalent PVT heating system (i.e., PVT as sole heat source for the brine-to-water heat pump), we recommend planning with at least 2 modules per kW of heating capacity of the heat pump*. For example, with an 8 kW brine heat pump, you would need at least 16 Sunmaxx PVT modules. A larger dimensioning of the PVT system is always beneficial to increase the overall system efficiency, but it is not strictly necessary for functionality.

*Depending on location and structural conditions, this recommendation may vary. Always consult a Sunmaxx expert to ensure that the PVT system is properly sized to meet your individual heating needs.

The maximum heat that can be generated by our PVT modules (in summer) ranges between approximately 25 °C and 45 °C, depending on the application and weather conditions. Our hybrid modules therefore provide what is known as low-temperature heat, which is later increased using a brine heat pump.

Yes, our hybrid modules are also suitable for large-scale projects, such as industrial applications or cold local heating networks. High-temperature heat pumps can also be used in combination with our PVT modules. Thanks to the low pressure loss, up to 24 Sunmaxx modules can be connected in parallel. This allows for maximum efficient use of available roof or open space and enables cost-effective installation.

We are happy to provide initial consultation for large-scale projects and connect you with qualified planning experts. Please contact us at office@sunmaxx-pvt.com.

Yes, a PVT system can also supply a multi-family building with heat year-round. This can be done either monovalently (i.e., PVT as the sole heat source for the brine-to-water heat pump) or bivalently (e.g., in combination with ground probes, ground collectors, or an ice storage system).

Sunmaxx is solely a module manufacturer. Our product range does not include heat pump models, we only provide the energy source. Hoewever, we maintain partnerships with various heat pump manufacturers. Through our installation partners, you can obtain a PVT heating system as a complete solution.

Sunmaxx is an open, manufacturer-independent system. Our PVT modules are compatible with almost all brine-to-water heat pumps. This includes models that already operate with natural refrigerants such as propane R290.

PVT modules supply what is known as low-temperature heat, typically at the level of ambient air temperature. Even during peak summer conditions, the available direct heat is usually not sufficient for domestic hot water production. Therefore, the system always relies on the operation of a brine-to-water heat pump. An exception to this are swimming pools and outdoor pools – in this specific application, temperatures of around 26 °C are sufficient for heating, meaning a heat exchanger is enough and no heat pump is required.

In general, heat pump cycling can be reduced by selecting a suitable buffer tank. For a system tailored to your needs, please contact our partner network.

The COP (Coefficient of Performance) describes the ratio between electricity consumption and the amount of heat delivered, calculated for a specific location and over the course of a year.

The SCOP (Seasonal Coefficient of Performance) is more specific, as it also takes seasonal influences into account, providing a weighted average. This makes it easier to directly compare different heat pump systems.

A PVT heating system – or a heat pump that is combined with a PVT system – is among the most efficient and sustainable heating solutions on the market. In bivalent systems (i.e., the PVT system is combined with an additional energy source, such as one or more ground probes), seasonal performance factors above 6 are possible.
In monovalent systems, where PVT serves as the sole heat source for the brine-to-water heat pump, the seasonal performance factor (SCOP) typically ranges between 4 and 4.5. Top-performing systems can even reach a SCOP of over 5.
Both configurations are significantly more efficient and economical than air-to-water heat pumps (which usually achieve a SCOP of around 3 or less), as the PVT system uses not only ambient air but also solar radiation as a heat source.

Larger buildings and applications often require a significant amount of activated ground volume (e.g., via geothermal probes), as sole geothermal systems are not an inexhaustible resource. The ground probes will eventually cool down. However, if these probes are regenerated using a PVT system – for instance, by transferring excess heat from the modules into the ground during summer – high thermal yields can be achieved over the long term. This approach maintains high source temperatures in the ground and prevents the probes from cooling out.
From a purely technical standpoint, a ground probe could be operated indefinitely in this way. Thanks to geothermal regeneration with PVT, significantly fewer probes and/or drilling meters are needed. This drastically reduces investment costs for climate-friendly heating and cooling—by up to 75% in some cases.

Yes, the typical heating operation of a PVT heat pump can be reversed during the summer months. Our modules can easily be used for cooling – either actively through reverse operation of the brine-to-water heat pump or passively via infrared radiation into the cool night sky.
With active cooling, the waste heat can be stored in a buffer tank during the day and discharged at night through the PVT modules for cooling.

The cooling capacity of a PVT heating system does not achieve temperature differences as high as those of a conventional air conditioner. This is not primarily due to the PVT system or the brine-to-water heat pump, but rather because underfloor heating (or other common radiators) is less effective at dissipating cold compared to an air conditioning unit. Nevertheless, a pleasant and noticeable cooling effect can be achieved with a PVT system and brine heat pump, given the circumstance that the cooling is continuous. We recommend to maintain a consistent indoor temperature of, for example, around 22 °C. Additionally, we recommend limiting the temperature of the heating water and surfaces (known as dew point monitoring) to prevent condensation – since cold air is known to retain less moisture than warm air.
In direct comparison to an air conditioning unit, cooling with a PVT system is a significantly more efficient and quieter solution.

Passive cooling utilizes natural processes to remove heat from a room (or the building as a whole). No active refrigerants or energy-intensive processes are used. During passive cooling, the circulation pumps on both sides operate, but the heat pump itself remains off. Excess heat is absorbed through the floor and radiators and transferred via the heating circuit to the PVT system. After passing through the heat exchanger, the heat is released to the surrounding air via the collector surface.
In PVT modules, passive cooling works through infrared radiation toward the cold night sky (known as radiative cooling). This enables cooling, even in tropical nights with temperatures of 25 °C or higher, down to below 20 °C.

Active cooling uses electrical energy to reverse the Carnot cycle in the brine-to-water heat pump. The electrically powered compressor in the heat pump remains in operation, with only the direction of the refrigerant flow being reversed. Active cooling is carried out using Sunmaxx modules, offering very high efficiency ratios (EER) of over 6. This makes the process significantly more efficient than that of a conventional air conditioning unit, which typically has an EER of around 3.

With Sunmaxx PVT modules, both passive and active cooling are possible. The so-called Energy Efficiency Ratio (EER) indicates the efficiency levels that can be achieved when cooling with a PVT system and brine heat pump, and thus serves as a measure of performance.
By far the highest EER – between 8 and 10 or even higher – is achieved through passive cooling, followed by active cooling with an EER of approximately 4.5 to 6. In contrast, a conventional air conditioning unit typically has an EER ranging between 2 and 4.

In direct comparison, the efficiency of both passive and active cooling is significantly higher than that of an air conditioner – however, this comes at the cost of cooling capacity. Conversely, an air conditioning system requires substantially more electricity to achieve the same cooling effect.

The use of PVT as a heat source has no impact on individual room control (IRC). Whether implementation or retrofitting makes sense depends on the intended use of the rooms and your specific preferences.

No, Sunmaxx PVT modules do not overheat. The full-surface aluminum heat exchanger on the back of the module simply dissipates excess heat into the air, much like a passive heat sink. As a result, the temperature within the module rises – but this is not an issue for the Sunmaxx system.
However, to increase the efficiency of the solar cells and reduce the load on the heat pump, we recommend using a waste heat storage tank that is cooled overnight via our modules.