A groovy way to boost solar power efficiency

Solar electricity panels are made of solar cells that capture the sun’s energy and convert it into electricity.

The invention of the solar cell was credited to French scientist Edmond Becquerel in 1839, who discovered that light could be used to increase electricity generation by placing two electrodes into a conducting solution. This was defined as the photovoltaic effect, and is at the core of the solar cell technology found in solar panels today.

Solar panels turn sunlight into direct current electricity before an inverter converts it into alternating current electricity that is fed into a grid or stored in a battery. 

Currently, 3.3 per cent of the 29 million homes in the UK generate electricity from solar panels and 500 solar farms provide energy directly to the Grid.

While this renewable source of energy doesn’t require fuel or produce polluting gases, the manufacturing of most solar panels is energy intensive and harmful to the environment.

Silicon is an abundantly available material but, the production of silicon solar panels creates a lot of waste during the heat-intensive manufacturing process.

Most solar panels are made of silicon because they deliver the highest efficiency compared to the alternative polycrystalline solar panels or thin-film solar panels. 

The average silicon solar panel efficiency stands at 22-25 per cent. There are panels based on compound semiconductors that have 40 to 50 per cent efficiency, but they tend to be a lot more expensive and have even more complex and harmful manufacturing processes.

But what if there was a way to improve the efficiency of solar panels and reduce the embodied energy (energy required in production), to make solar an even more sustainable technology?

Professor David Lidzey, from the Department of Physics and Astronomy, collaborated with energy technology company Power Roll Ltd to create a new solar cell design. The innovative solar design has micro-grooves embossed onto the surface that are a fraction of the width of a human hair and have the capability to drive down costs of manufacturing and even make solar power more efficient.

“Silicon cells themselves are relatively heavy and not particularly flexible. For many years, we’ve been looking at ways to make solar cells using printing technologies. Through this, we’ve found a way to reduce manufacturing complexity and make steps towards low cost and high energy efficient solar cells” explains David.

A powerful collaboration

Power Roll Ltd is a technology company based in the North East developing energy generation and storage products. 

In a study published in the journal Energy and Environmental Science, researchers led by Professor David Lidzey and Power Roll Ltd demonstrated how embossing a surface with micro-grooves forming ‘back-contact devices’ could make solar-cells easier to manufacture.

David and his team, which included post-doctoral researchers and students, worked with Power Roll Ltd to develop a new solar cell design. The research discovered that by coating opposing walls of micro-grooves with different electrical contacts, and then filling the groove with a solution-processable semiconductor, it was possible to create a new type of back contacted solar cell.

“The idea was first developed and patented by Power Roll Ltd – making devices inside micro-grooves hadn’t been done before. The idea itself is really novel and we’ve been working closely together for a number of years to develop prototypes that prove this method works” says David. 

The design removes many of the manufacturing process steps and is fully compatible with solution-processable semiconductors such as perovskites. This reduces the need for heat-intensive manufacturing processes. Other benefits of the design include the ability to remove expensive transparent conductive oxides, the use of simple and low cost electrical interconnections and ability to tune electrical output to match user requirements.

Halide perovskites are a family of materials that have potential for high performance and low production costs in solar cells.When produced at scale, perovskite manufacturing costs are forecast to be as low as a tenth of the cost of other typical solar materials. 

Solar modules produced using the perovskite material weigh a fraction of typical silicon solar cells and have a carbon footprint that is up to twenty times lower. 

The flexibility of the material also makes it easier and cheaper to transport, allowing communities that couldn’t access traditional solar panels to access electricity.

A brighter future?

Following the work published in the paper, researchers from the University of Sheffield and Power Roll have successfully produced working mini-module demonstrators. Power Roll is now focusing on scaling up the technology for commercialisation and widespread use, and increasing the efficiency of the solar cell.

“A key advantage to using this light material is that the panel can be stuck onto any surface. In the UK, you currently have to think twice about adding thick solar panels onto relatively fragile roofs of warehouses that are not really designed to be load-bearing. With this lightweight solar technology, you could  essentially stick it anywhere. This could be a gamechanger for solar energy in low and middle income countries” adds David.

Written by Alina Moore, Research Communications Coordinator