For cool BIPV

Heat Blocking Films

Solar Energy is the largest and abundantly available power source there is. Harvesting solar energy via solar panels is a preferred option for on-site power generation in buildings and a necessary step towards net zero energy consumption. To improve acceptability and increase rate of implementation, building integrated photovoltaics (BIPV) are an important development. BIPV can be smoothly integrated into a buildings skin, offer freedom of design and enable new surfaces, such as the façade, to be used for sunlight harvesting.

Since not all sunlight can be transformed into energy by standard solar panels, part of the light is heating up the module. The problem of overheating is increased in BIPV since they are integrated into a buildings skin and therefore less well ventilated than roof mounted or free-standing PV.

To solve this issue, we develop within SUNOVATE a new type of encapsulant that blocks long wavelength solar radiator, which cannot be converted into electricity, while not impacting the wavelength region that is used by the solar panel to generate energy.

Heat Blocking Film

Solar panels with heat blocking film

At temperatures above 25°C a solar panels power output is reduced by 0.5% per degree Celsius. That means a 250 Watt Peak (Wp) panel at 50°C will produce less than 225 Wp. At temperatures of 80°C and higher, permanent and irreparable damage to PV panels can occur, making them work less well or no longer at all.

Our new heat blocking encapsulant is used in standard crystalline silicon solar panels and BIPV to keep the solar panels cool while enabling a high power output.

The functional materials

Within SUNOVATE, we are testing several commercial infrared blocking pigments for the possibility of use in heat blocking solar panels. The pigments need to fulfill very specific criteria related to their transmission, reflection and absorption of light in several wavelength regions. Furthermore, the particle size is crucial, which will be reduced to nanometer size via bead milling, if necessary.

After selection and modification, the IR blocking pigments are surface functionalized and integrated into polyolefin elastomer (POE) via masterbatch. After compounding, the pigmented polymer material is extruded via a pilot sized single screw extruded to provide pigmented polymer films. For perfect optical properties and low haze values, a good particle distribution in the polymer film without agglomeration is necessary.

The pigmented polymer films are used as encapsulants for lamination of pilot scale crystalline silicon solar panels. Within SUNOVATE, we will demonstrate the technology on pilot scale and will produce full sized PV demonstrators of 1×1.5 m².

Analysis and performance monitoring

For analysis and performance monitoring a new type of sensor will be integrated into the laminated solar panel. The sensor is made of thin glass fibers and is based on a Fiber Bragg grating. It enables fast, accurate and precise temperature and mechanical stress measurements. This improves the quality control and performance monitoring of our new development.

Power increasing and long-lasting solar panels

The heat blocking film not only increases the total annual power output of BIPV, but also increases the lifetime of solar panels.

Technology demonstration and performance monitoring

Our pilot scale heat blocking solar panel demonstrators will be installed in test buildings at SolarBEAT in Eindhoven (NL) and at EnergyVille in Genk (VL). The demonstrators will be monitored and compared to standard PV cells for one year while recording the most important parameters, such as performance, power output, temperature and environmental stability. The aim of the project is to bring the technology to TRL 6.

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