New cells shatter solar energy efficiency records

The sight of solar panels installed on rooftops and large energy farms has become commonplace in many regions around the world. Even in grey and rainy UK, solar power is becoming a major player in electricity generation.

This surge in solar is fuelled by two key developments. First, scientists, engineers and those in industry are learning how to make solar panels by the billions. Every fabrication step is meticulously optimized to produce them very cheaply.

The second and most significant is the relentless increase in the panels’ power conversion efficiency – a measure of how much sunlight can be transformed into electricity.

The higher the efficiency of solar panels, the cheaper the electricity. This might make you wonder: just how efficient can we expect solar energy to become? And will it make a dent in our energy bills?

Current commercially available solar panels convert about 20-22% of sunlight into electrical power. However, new research published in Nature has shown that future solar panels could reach efficiencies as high as 34% by exploiting a new technology called tandem solar cells. The research demonstrates a record power conversion efficiency for tandem solar cells.

What are tandem solar cells?

Traditional solar cells are made using a single material to absorb sunlight. Currently, almost all solar panels are made from silicon – the same material at the core of microchips. While silicon is a mature and reliable material, its efficiency is limited to about 29%.

To overcome this limit, scientists have turned to tandem solar cells, which stack two solar materials on top of each other to capture more of the Sun’s energy.

In a new Nature paper, a team of researchers at the energy giant LONGi reported a new tandem