An international research team led by the Universitat Politècnica de Catalunya—BarcelonaTech (UPC) has created a hybrid device that combines, for the first time ever, molecular solar thermal energy storage with silicon-based photovoltaic energy. It achieves a record energy storage efficiency of 2.3% and up to 14.9% total solar energy utilization.
Photovoltaic solar energy has become one of the most important renewable sources for electricity production in the energy transition context, but it still presents challenges due to intermittent solar production and fluctuating energy demand. Therefore, efficient storage systems are needed to ensure energy availability when demand increases.
However, these technologies still do not perform optimally, mainly due to the heating they experience, which affects energy production and the durability of photovoltaic systems. Additionally, current storage technologies, such as batteries, rely on unsustainable materials.
An international research team led by ICREA professor Kasper Moth-Poulsen from the Department of Chemical Engineering of the UPC at the Barcelona East School of Engineering (EEBE) has now developed a technology to address both issues. It is the first hybrid device that combines a silicon solar cell with an innovative storage system called MOST, which stands for molecular solar thermal energy storage systems. The results have been published in the journal Joule.
MOST consists of organic molecules that, when irradiated with high-energy photons such as ultraviolet light, undergo a chemical transformation and store this energy for later use. A particular feature of the system is that these molecules also provide cooling to the photovoltaic cell by acting as an optical filter and blocking photons that would normally cause heating and reduce system efficiency. In this way, the device allows both the generation of electricity and the storage of chemical energy.
Improvements in energy efficiency
The new device significantly improves energy efficiency. Experimental tests have achieved a record energy storage efficiency of 2.3% for molecular thermal solar energy. The integration of this hybrid system will also lower photovoltaic cell temperature by up to 8°C, thus reducing energy losses due to heat and increasing efficiency by 12.6%. The combined device operates with a solar utilization efficiency of up to 14.9%, which represents an improvement over the two hybrid solar systems operating independently.
Combining photovoltaic energy with molecular thermal storage will not only enhance energy efficiency but also help to reduce reliance on fossil fuels and minimize the environmental impact associated with other forms of energy storage, such as batteries based on scarce and polluting materials.
