Hybrid solar panels (photovoltaic/thermal)

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Hybrid solar panels combine photovoltaic and thermal technologies to simultaneously produce electricity and domestic hot water. They optimize the use of solar energy and offer greater energy efficiency. Their operation is based on photovoltaic cells and an integrated thermal system using a heat transfer fluid. The advantages of hybrid panels include a smaller footprint, improved cell cooling, longer service life and reduced greenhouse gas emissions. They are an attractive energy solution for residential, commercial and industrial applications.

How hybrid solar panels work

Hybrid solar panels work by combining two technologies: photovoltaics and solar thermal. This combination enables the simultaneous production of electricity and heat from solar energy, optimizing the use of this renewable resource. Here’s a detailed overview of how these panels work:

Photovoltaic cells: Hybrid solar panels incorporate photovoltaic cells, usually made of silicon, which convert sunlight into electricity. When photons strike the surface of the panel, they transfer their energy to the electrons inside the cells. These electrons are then set in motion, creating a direct current (DC) which is collected by metal contacts.
Thermal solar collectors: In addition to photovoltaic cells, hybrid panels contain thermal solar collectors. These collectors absorb heat from the sun and transfer it to a heat-transfer fluid, usually water or a mixture of water and glycol, which circulates through tubes at the back of the panels. The heat captured can then be used to heat domestic hot water or power a central heating system.
Cell cooling: One of the challenges of traditional photovoltaic solar panels is their sensitivity to temperature. In fact, as cell temperature rises, efficiency decreases. In hybrid solar panels, the presence of solar thermal collectors cools the photovoltaic cells by dissipating the heat they produce. This thermal regulation improves the cells’ energy efficiency and extends their lifespan.
Energy conversion: The electricity generated by photovoltaic cells must be converted into alternating current (AC) to be compatible with household electrical appliances and the power grid. An inverter is therefore used to transform direct current into alternating current. In addition, a control and regulation system manages the distribution of the energy produced, between direct consumption, storage in batteries, or injection into the power grid.

Types of hybrid solar panels

There are different types of hybrid solar panels, depending on how photovoltaic and thermal technologies are combined. The two main types of hybrid solar panels are air panels and water panels. Here’s a detailed description of both types:

Hybrid air solar panels (PVT-air):

Hybrid air solar panels incorporate a ventilation system behind the photovoltaic cells. Air circulates through this space and absorbs the heat generated by the cells, which is then used to heat the interior of a building or to preheat the air entering a controlled mechanical ventilation (CMV) system.

The main advantage of air-cooled hybrid solar panels is their simplicity and ease of installation. They require no piping system or heat transfer fluid, which reduces costs and the risk of leakage. However, their thermal efficiency is generally lower than that of water-cooled hybrid solar panels.

Hybrid solar water panels (PVT-water):

Hybrid water solar panels are equipped with tubes containing a heat transfer fluid (usually water or a mixture of water and glycol) located behind the photovoltaic cells. The heat generated by the cells is transferred to the fluid, which is then circulated through a central heating system or hot water tank to heat domestic hot water.

Hybrid water solar panels offer higher thermal efficiency than hybrid air solar panels, as the heat transfer fluid is more efficient at capturing and transporting heat. However, their installation is generally more complex and costly, requiring a piping system and heat exchanger to transfer the heat from the heat transfer fluid to the domestic hot water or heating system.

Advantages of hybrid solar panels

Hybrid solar panels combine photovoltaic and thermal technologies to produce both electricity and heat. They offer a number of advantages and disadvantages compared with pure photovoltaic or thermal solar panels.

Advantages of hybrid solar panels :

Increased energy efficiency: Hybrid solar panels make it possible to use more of the sun’s energy by simultaneously producing electricity and heat. This makes them more efficient than photovoltaic or thermal panels alone.
Space-saving: Hybrid solar panels optimize roof space or installation area, as they replace two separate systems with a single one. This can be particularly useful in urban areas where space is limited.
Improved photovoltaic performance: Recovering the heat produced by photovoltaic cells reduces their operating temperature. Photovoltaic cells are more efficient at lower temperatures, which slightly improves electricity production compared with traditional photovoltaic panels.

Disadvantages of hybrid solar panels :

Cost: Hybrid solar panels are generally more expensive than photovoltaic or thermal panels alone, due to the complexity of their manufacture and installation. However, long-term energy savings can offset this higher initial cost.
Complexity of installation: Hybrid solar panels can be more complex to install than photovoltaic or thermal panels alone, particularly for hybrid water panels. This can lead to higher installation costs and the need for specialized professionals.
Maintenance: Hybrid solar panels, especially water-cooled ones, may require more regular maintenance to ensure proper operation. The piping system and heat transfer fluid need to be checked and maintained to avoid leaks and performance problems.

Hybrid / photovoltaic / thermal comparison

To illustrate the comparison between hybrid solar panels and traditional photovoltaic and thermal panels, let’s take the example of a single-family home in the south of France. The house has a roof surface of 30 m² available for the installation of solar panels. The aim is to cover electricity and domestic hot water needs.

Traditional photovoltaic panels: Let’s assume we install 30 m² of monocrystalline photovoltaic panels with an efficiency of 20%. This installation could produce around 6 kWp (kilowatt-peak) of electricity. However, this installation would not cover domestic hot water needs.
Traditional solar thermal panels: Installing 30 m² of traditional solar thermal panels would cover a large part of the house’s domestic hot water needs. However, this installation would not generate electricity to power other electrical appliances.
Hybrid solar panels: By choosing to install 30 m² of hybrid solar panels with a photovoltaic efficiency of 18% and a thermal efficiency of 55%, we could generate around 5.4 kWp of electricity and cover a significant proportion of domestic hot water needs. In this way, hybrid solar panels optimize the use of available roof space and ensure the combined production of electricity and hot water.

In this case study, hybrid solar panels offer an interesting compromise between electricity and domestic hot water production. They make more efficient use of available space and meet the home’s energy needs.

Companies

DualSun is a French company specializing in hybrid solar panels. Their main model, the DualSun Spring panel, integrates monocrystalline PERC photovoltaic cells and a polymer heat exchanger for hot water production. These panels offer a photovoltaic efficiency of around 19.4% and a thermal efficiency of around 60%.
Heliotherm is an Austrian company offering air-water hybrid solar panels. Their flagship model, Heliotherm PVT, combines polycrystalline photovoltaic cells with a heat exchanger integrated into the back of the panel to recover heat. These panels have a photovoltaic efficiency of around 15.4% and a thermal efficiency of around 35%.
Solarus is a Dutch company specializing in hybrid solar panels. Their PowerCollector model is an innovative hybrid solar panel that uses mirrors to concentrate sunlight on photovoltaic cells and a thermal absorber. The PowerCollector has a photovoltaic efficiency of around 15% and a thermal efficiency of around 45%.
Sunerg Solar is an Italian company offering hybrid solar panels. Their flagship model, the HSS (Hybrid Solar System) panel, integrates monocrystalline photovoltaic cells and a copper heat exchanger for hot water production. These panels have a photovoltaic efficiency of around 18.4% and a thermal efficiency of around 55%.