Scientists in the US claim to have developed a new type of two-sided perovskite solar cell that can generate up to 20% more power than their one-sided alternatives.

A team at the US Department of Energy’s National Renewable Energy Laboratory (NREL) announced the breakthrough in their research this week.

Kai Zhu, a senior scientist in the Chemistry and Nanoscience Center at NREL, said this new perovskite cell “can operate very effectively from either side”.

The team said that past research into bifacial perovskite solar cell research has resulted in devices considered “inadequate” compared to their monofacial counterparts, which have a current record of 26% efficiency.

“Ideally,” they said a bifacial cell “should have a front-side efficiency close to the best-performing monofacial cell and a similar back-side efficiency”.

The researchers now report having been able to make a solar cell where the efficiency under illumination from both sides are close together.

The lab-measured efficiency of the front illumination reached above 23%, they reported. From the back illumination, the efficiency was about 91%–93% of the front.

The researchers found the optimal thickness for the perovskite layer on the solar cells was 850 nanometers, over 80 times thinner than a human hair.

To evaluate the efficiency gained through bifacial illumination, the researchers placed the cell between two solar simulators. Direct light was aimed at the front side, while the back side received reflected light.

Bifacial perovskite solar panels are more expensive than one-sided ones at this stage, say the researchers. However, they say that over time bifacial modules “could end up being better financial investments because they generate 10%–20% more power.”

The US Department of Energy Solar Energy Technologies Office funded the research.

Another team of researchers in Australia this week announced that they have shown that perovskite solar cells damaged by proton radiation in low-earth orbit can completely self-heal through a heat treatment in vacuum.

Perovskite materials have been the focus of intense research in the solar sector due to what many see as their huge potential as a more efficient, lower cost alternative to the crystalline silicon that currently dominates the market as a base material for PV technology.