A research team from the University of Alcalá (UAH) in Spain has developed a prototype of a solar panel with integrated geothermal cooling by connecting it to a shallow borehole. With this prototype, the team observed a 14% increase in energy efficiency, an important step in photovoltaic solar technology.
Ignacio Valiente, from the Mechanical, Electrical and Thermal Technologies research team, leads a group working on the project "Sustainable improvement of solar panel energy efficiency through modular geothermal cooling systems". The project is being funded by the Community of Madrid after bringing together young researchers in 2019. This research is also considered the best entry for the 2022 conference on renewable energy and environmental engineering.
The research team focused on photovoltaic solar energy because it is the cheapest renewable energy source. Despite the low cost, the low energy efficiency of solar panels is still a major constraint. The energy efficiency of solar panels is typically no more than 20% based on the energy they receive and the electricity they output, with most of the waste energy being converted into heat.
Recognising that the temperature underground is stable at around 15 degrees Celsius, the research team proposed a cooling system connecting the shallow geothermal reservoir to the panels and built a prototype. The prototype is a solar panel with a heat exchanger integrated at its rear, which is connected to another heat exchanger located 15 metres below ground, circulating coolant through the system by means of a small pump.
The research team compared the prototype solar panel with a standard panel. They observed that with this system the temperature of the solar panels was reduced by 20 degrees Celsius and the net energy efficiency of the system increased by 14%. The temperature of the underground reservoir was kept relatively constant due to the minimal heat coming from the panels.
The research team has also received interest in the technology from a number of companies, but they say more research is needed before the manufacturing, operating and maintenance costs of the technology can be reduced.