New Hybrid solar cells harness energy from … raindrops?

Renewable energy is the cleanest and inexhaustible source of energy. They are a great alternative to fossil fuels.

Renewable energy doesn’t emit any greenhouse gases in the environment. They are environment-friendly and help us tackle the most important concern of the 21st Century – Climate Change.

Solar is one of the most important forms of renewable energy. Sun is an inexhaustible source of energy and solar cells help capture that clean energy for both commercial and domestic purposes. Despite all these advantages, Solar cells are not efficient when it comes to producing energy during rainy seasons. Since the input energy gets reduced, solar cells become practically useless when rain clouds are overhead.

But what if we could overcome this problem?  What if we could actually generate energy from raindrops?

Scientists from the University of Soochow, China have overcome the design flaw of solar cells by allowing them to generate energy both in the sunny and rainy season.

This technology holds the potential of revolutionizing renewable energy completely.

The key part of this new Hybrid solar technology is the triboelectric nanogenerator or TENG. A device capable of producing an electric charge from the friction of two materials rubbing together.

How Hybrid solar cells work?

These new hybrid solar cells works using a material called Graphene. It has the ability to produce energy from raindrops.

Like any other solar panel, these hybrid solar cells also generate electricity during a normal sunny day using the current technology, but when cloud gathers and raindrop falls, this solar panels system switch to its graphene system.

Graphene, in its liquid form, can produce electricity due to the presence of delocalized electrons that help us create a pseudocapacitor framework. This pseudo framework helps us generate electricity.

When raindrops fall on hybrid solar panels, they get separated as positive ions and negative ions.

These positive ions are mainly salt-related ions, like sodium and calcium which accumulates on the surface of graphene. These positive ions interact with the loosely associated negative ions in graphene and create a system that acts like a pseudocapacitor.

The difference in potential between these ions produces current and voltage.

Although, it is important to mention that this is not a first attempt to invent all-weathered Solar panels. Earlier, researchers created a solar panel with triboelectric nanogenerator on top, an insulating layer in the middle and solar panel at the bottom. But this system possessed too much electrical resistance and sunlight was not able to reach the solar cells due to the opaque nature of insulators.

The newly designed hybrid solar panel is an efficient device, where the triboelectric nanogenerator and the solar panel share a common and transparent electrode. There are special grooves incorporated in the material which increases the efficiency of both raindrops and sunlight captured.

According to the researchers, the idea of special grooves was derived from commercial DVD’s. DVD’s come pre-etched with parallel grooves just hundreds of nanometer across. Designing the device with this grooves helps to boost the surface interaction of raindrops and sunlight that would be otherwise lost to reflection.

Benefits of Solar Hybrid Panels  

Until now solar cells have this drawback of producing energy only in the presence of sunlight, making it impossible to harness energy during the rainy season. Countries in the northern hemisphere were not able to switch to solar energy due to the presence of low-intensity sunlight.

With hybrid solar panels, anyone in the world could harness solar power. Researchers expect that in a few years, these panels will be efficient enough to provide electricity for homes and businesses and thus ending our dependency on fossil fuels.

They will also save a lot of money on daily electricity bills. Even though the initial setup costs are higher, countries with good exposure to both sunlight and rain can expect a good ROI.

Hurdles in Solar hybrid panels    

The current designs are not efficient enough to be used commercially. The device was tested in various simulated weather conditions, in sunlight, the device was able to produce around 13% efficiency and simulated raindrops had an efficiency of around 6%.

Currently used commercial solar cells gives an efficiency of around 15%, thus the new design is a viable option for presently used solar panels. However, the efficiency of triboelectric nanogenerators was not reported.

Conclusion

With continuous depletion of non-renewable sources and the disastrous climate change occurring due to fossil fuels, many countries are moving towards eco-friendly alternatives. Solar energy is one of the cleanest energy available. With the advent of new technology like the hybrid solar panels, we can hope to achieve a viable method of electricity generation.

Researchers are continuously trying to improve the efficiency of hybrid solar cells in order to make it commercially available. This will boost our efforts of producing energy in all-weather condition, which is not possible with the currently available technology. With the expansion of solar energy projects worldwide, researchers of hybrid solar cells are expecting to roll out commercial designs in next five years.

Researchers at china are even trying to integrate this new technology into mobile and electronic device such as electronic clothing.