Bio-Inspired Solar ‘Leaf’ Generates Electricity From Sunlight by Mimicking Transpiration in Plants

As the impact of global warming becomes more evident, the shift towards renewable energy has strengthened in recent years. One of the alternatives to fossil fuel is solar energy which uses photovoltaic (PV) cells to convert sunlight into electricity.

Conventional PV cells are not so efficient since only 10-25% of solar energy is converted into electricity, and the rest of the unusable solar energy can make the PV cells extremely hot during summer days. Experts employ active thermal management techniques such as removing heat through water or air flows to cool PV cells down. However, this method adds complexity to the technology since heat-exchanging structures are required. It can also lead to parasitic electricity consumption, which decreases energy.

PV Technology With Leaf-Like Design

At the Imperial College London, a team of researchers attempted to redesign the PV technology in such a way that it will co-generate heat, electricity, and clean water while having effective electrical performance. The technology, named photovoltaic leaf (PV-leaf), is inspired by the photosynthetic mechanisms of plants and is created using low-cost materials.

The PV-leaf simulates the transpiration process, where water can move and be released into the environment. It is made of natural fibers that imitate the natural vein bundles in leaves, while the hydrogels mimic the sponge cells.

This process allows water to cover an entire cell and evaporate, driving water from a separate water tank to a solar cell without using a pump. The released water vapor and heat can then be captured within a collector in addition to collected electricity. These are all gathered in a smart, neatly packaged system that can effectively remove heat from solar PV cells.

According to Professor Christos Markides from the Clean Energy Processes Laboratory, implementing this innovative leaf-like technology can help accelerate the transition to sustainable energy sources. It addresses two global challenges involving the need for increased energy supply and the demand for freshwater sources.

Upon testing the product, it was found that PV-leaf demonstrated higher efficiency than conventional-shaped solar panels. It can generate over 10% more electricity than traditional solar panels, which lose up to 70% of the solar energy to the surroundings.

The new design also produces more than 40 billion cubic meters of freshwater every year and eliminates the use of costly porous materials, control units, fans, and pumps. Additionally, it can adapt to ambient temperature and variations in solar conditions.

Taking Inspiration from Nature

The plant leaf is an amazing natural factory. It contains several different layers and structures which enable the movement of water from the roots to the leaves in a process known as transpiration. Transpiration plays an important role in photosynthesis by keeping the leaves cool and functioning.

The transpiration of plant leaves demonstrates a highly effective thermal management method. For instance, trees are very effective in transporting water from the soil to a height of several meters to keep the leaves cool and protect photosynthesis and other important functions. This mechanism helps maintain the temperature of leaves within a stable range regardless of weather conditions.