In this configuration, the thermal circuit from the PVT array feeds the heat pump evaporator directly. The PVT panels act as a warmer source than outdoor air under suitable conditions, helping the heat pump work with a better source temperature. This is usually the simplest PVT + heat pump configuration.

How It Works

The PVT array collects low-temperature heat. This heat is transferred through a glycol or brine circuit to the heat pump evaporator. The heat pump upgrades the heat to a usable temperature for domestic hot water or space heating. At the same time, the PV side of the PVT panel generates electricity that offsets part of the heat pump or circulation pump power demand.

Best-Fit Projects

This configuration is most suitable for new residential buildings, single-family houses, small villas, low-complexity heating and DHW systems, and projects where PVT and heat pump can be sized together from the beginning.

Key Design Checks

Before choosing direct connection, EPCs should confirm heat pump compatibility with glycol or brine source fluid, minimum and maximum evaporator inlet temperature, required PVT array size, flow rate through the PVT circuit, freeze protection requirements, and control logic between the PVT loop and heat pump operation.

Main Limitation

The main limitation is integration flexibility. The heat pump and PVT field must be selected as one system. If the heat pump is not suitable for a PVT source circuit, or if the project already has an existing heat pump, a buffer tank configuration may be safer.

In this configuration, the PVT array heats a low-temperature buffer tank. The heat pump then uses the buffer tank as its source. This adds one more component, but it can make the system easier to control and more suitable for variable loads.

How It Works

The PVT panels transfer heat to a buffer tank. The buffer tank stores low-temperature heat and smooths the difference between solar collection timing and heat pump demand timing. When the heat pump runs, it draws heat from the buffer instead of directly from the PVT array.

Best-Fit Projects

This configuration is suitable for residential retrofit projects, buildings with variable heating demand, projects where heat pump operation does not always match solar collection, larger houses or small commercial buildings, and systems where more stable source temperature is needed.

Why the Buffer Helps

The buffer tank provides thermal inertia. It reduces short cycling, helps control source temperature, and separates the PVT collection circuit from heat pump operation. For retrofit projects, this separation can make system integration easier because the existing heat pump or hydraulic layout may not be designed for direct PVT connection.

Main Limitation

The buffer tank adds cost, space requirement, heat loss, and control complexity. If the project is small and the heat pump can be directly matched with the PVT source, Configuration 1 may be simpler.

In this configuration, the PVT system contributes directly to domestic hot water storage when solar conditions are favorable. The heat pump provides backup or final temperature lift when the PVT output is not enough. This option is especially relevant for buildings with strong year-round hot water demand.

How It Works

The PVT thermal circuit transfers heat to a DHW storage tank. During high solar periods, especially in summer, the PVT system can preheat or partially heat domestic hot water directly. When the solar contribution is insufficient, the heat pump raises the water temperature to the required setpoint.

For direct DHW applications, the required temperature target matters. Unglazed PVT is generally better as a low-temperature heat pump source, while configurations targeting higher direct solar thermal temperatures may benefit from different PVT panel specifications.

Best-Fit Projects

This configuration is suitable for hotels, hospitals, student dormitories, apartment buildings, commercial buildings with year-round DHW demand, and projects where summer hot water load is high.

Key Design Checks

EPCs should confirm daily DHW consumption profile, DHW storage volume, required delivery temperature, Legionella control requirements, whether direct PVT heat or heat pump boosting is preferred, and seasonal control logic between PVT and heat pump.

Main Limitation

The system requires good control logic. In summer, direct solar thermal use may be prioritized. In winter, the heat pump may become the main heat source, with PVT serving as a low-temperature support source. If the control strategy is not clear, the system may become unnecessarily complex.

In this configuration, PVT supports the heat pump for space heating or DHW, while excess thermal energy can be directed to pool heating, especially in summer. This is useful because pools can act as a large thermal sink that absorbs low-temperature heat over long periods.

How It Works

The PVT array collects heat and supplies it to the heat pump source circuit or directly to the pool heating loop depending on system temperature and demand. When building heating or DHW demand is low, the pool absorbs excess thermal energy. This helps avoid wasting thermal output during warm seasons.

Best-Fit Projects

This configuration is suitable for hotels with swimming pools, resorts, sports facilities, wellness centers, schools or campuses with aquatic facilities, and commercial projects with both DHW and pool loads.

Why Pool Heating Improves Utilization

Many solar thermal systems face a mismatch between solar availability and heating demand. In summer, space heating demand is low, but solar availability is high. A pool can absorb low-temperature heat continuously, which makes it a useful thermal dump. This can improve annual PVT thermal utilization and reduce stagnation risk in suitable designs.

Main Limitation

The hydraulic system becomes more complex. The controller must decide whether thermal energy should go to the heat pump source, DHW tank, pool loop, or another priority load. This configuration is usually not necessary for simple residential buildings.

Not every roof should be filled entirely with PVT panels. In many commercial buildings, the best design is a mixed roof: PVT panels where thermal energy is useful, and standard PV panels where only electricity generation is needed.

How It Works

A portion of the roof is allocated to PVT panels connected to the heat pump or thermal system. The remaining roof area is filled with standard PV modules to maximize electricity generation. The PVT area is sized according to thermal demand and heat pump source needs. The PV area is sized according to electrical demand, grid export strategy, or self-consumption goals.

Best-Fit Projects

This configuration is suitable for large commercial roofs, hotels, factories, schools, hospitals, warehouses with office or DHW demand, and buildings with both thermal and electrical loads.

Roof Allocation Logic

Main Limitation

The project needs coordination between two panel types, two system designs, and sometimes two installation teams. Layout, wiring, pipe routing, maintenance access, and roof loading should be considered early in the design process.

In this configuration, PVT panels act as a heat source for a brine-to-water or liquid-to-water heat pump. In some projects, PVT can reduce dependence on ground loops or boreholes. This option is especially interesting in urban sites where drilling is expensive, restricted, or impossible.

How It Works

The PVT thermal circuit circulates brine or glycol through the panels. This source loop connects to a brine-to-water heat pump, similar to how a ground loop would normally connect to the evaporator side. The heat pump extracts low-temperature heat from the PVT loop and upgrades it for space heating or domestic hot water.

Research published in PV Magazine and academic studies have documented seasonal performance simulations of PVT panels in brine-water heat pump systems for heating single-family homes, showing the concept is technically viable under suitable conditions.

Best-Fit Projects

This configuration is suitable for urban buildings where borehole drilling is prohibited, retrofit projects with limited ground area, sites where drilling cost is too high, projects using brine-to-water heat pumps, and buildings seeking both solar electricity and a low-temperature heat source.

Key Design Checks

EPCs should confirm minimum winter source temperature, PVT array size relative to building heat demand, heat pump operating envelope, brine or glycol concentration, defrost or freeze protection strategy, whether PVT is the only source or a supplementary source, and seasonal performance expectations.

Main Limitation

PVT source temperature varies more than ground temperature. Ground loops are usually more stable, while PVT output depends on solar radiation, ambient temperature, wind, and season. This means careful sizing is essential. For some projects, PVT may reduce borehole size rather than fully replace the ground loop.