Cooling PV Modules Using Water Chambers
Researchers in Malta have developed an innovative cooling solution that can be retrofitted to existing photovoltaic (PV) modules. This technology, which uses a water chamber placed on the backside of the module, is claimed to increase net electrical output by over 9%.
Image: University of Malta
A team at the University of Malta has designed this aftermarket cooling system specifically for photovoltaic modules. The system incorporates a water chamber that can be inserted into a gap behind standard PV modules, which has been patented as the "Innovative Photovoltaic Cooling System" (IPCoSy), according to Luciano Mulè Stagno, the lead researcher. This technology could be particularly beneficial for offshore or floating solar installations, where water is readily available, and it could also enhance the efficiency of PV modules in both residential and industrial settings.
The system works by attaching a bottom plate securely to the base of a solar module's frame, creating a water chamber beneath the module's backside. This chamber is formed by the module's backsheet, the frame wall, and the bottom plate. The materials for the bottom plate may include options such as aluminum, stainless steel, and various polymers like PET, polypropylene, and polyimide.
The water chamber is equipped with an inlet and an outlet positioned on opposite sides of the frame wall. A temperature sensor, connected to an external junction box, monitors the module's backsheet. All components are sealed with waterproof materials to ensure durability.
To achieve uniform water flow within the chamber, the system includes a stream spreader connected to the inlet. This design aims to minimize the mixing of hot and cool water, thereby enhancing the cooling efficiency. The spreader is constructed from a T-elbow joint attached to the water inlet, with two 45-degree elbow joints extending from the other ends.
For ease of installation, a pipe adapter is connected to the water outlet on the outer frame wall. This adapter can rotate, ensuring consistent water contact with the PV module's backsheet, regardless of the installation angle. Water is pumped into the cooling system either from the sea or a water tank, driven by a pump.
The research team claims that this system can deliver a net electrical energy gain exceeding 9% and thermal efficiencies of up to 56%. However, the modified PV module with the cooling system is currently estimated to cost 9.7% more than standard modules, and the overall cost of a system incorporating this cooling technology is expected to be double that of current PV modules. These estimates are based on prototype models, and mass production is anticipated to reduce costs significantly. Additionally, the price becomes more justifiable when considering the combined thermal and electrical efficiencies.
The cooling technology is detailed in the study "Innovative Photovoltaic Cooling System," published in Innovation Disclosure. The researchers highlighted that the IPCoSy modules would be particularly effective in environments where water flow is already available for other processes, such as in reverse osmosis plants, where they could contribute to higher operational efficiency while generating renewable energy.
