Solar colours set to shine

While today’s silicon solar panels have become common, several factors – affordability, a complicated production process, and their bulky aesthetics – are holding them back.

Instead, imagine an alternative design: translucent, coloured, and cheaper to produce. For more than 25 years, our laboratory at the Ecole Polytechnique Federale in Lausanne (EPFL) has been working on dye-sensitised solar cells, a new generation of solar cells that meets these criteria.

Invented by Prof Michael Graetzel of EPFL, dye-sensitised solar cells do away with the dark silicone-based photovoltaic panels, replacing them with coloured, power-producing windowpanes.

Today, laboratories and firms around the world are working on improving and commercialising these easy-to-fabricate solar cells, integrating them into products such as iPad keyboards.

These dye-sensitised solar cells have a multitude of revolutionary features, some of which are particularly attuned to the needs of the Middle East. Conventional solar cells are most efficient when set up at an angle to face the sun at noon. Unfortunately, near the Equator that means they are nearly flat – inviting sand and dust to settle on them, blocking light and reducing power production.

The new dye-sensitised solar cells can be set up vertically and still maintain their efficiency, making them more useful in desert zones. Not only that, they are more efficient when the weather is hot.

Although dye-sensitised solar cells are less efficient at converting solar energy into electricity, they make up for this by converting diffuse and even artificial light, exploiting light from indoors and outdoors.

Dramatically lower production costs translate to cheaper power, and their visually pleasing appearance means that they can be integrated on to all kinds of structures without being eyesores.

Two years ago, another exciting development shook the solar panel research community. Researchers found that a key component of dye-sensitised solar cells could be replaced by perovskite, a long-studied class of chemical compounds that was found to be particularly well suited to converting sunlight into electricity.

Promising a new generation of hair-thin and highly efficient solar panels, capable of competing with or even outperforming silicone-based solar panels at a fraction of the price, expectations are high that perovskite cells could soon become the default technology.

Their versatility is a key strength. perovskite solar cells can easily be applied to any type of surface. In the future, they could cover entire walls, line roads, or coat the bodies of cars. And today, we are developing ways to use them to augment the performance of conventional solar panels: by adding a perovskite coating only one thousandth of a millimetre thick, we could potentially increase their output by about 25 per cent at virtually no cost. However, their lead content has raised environmental concerns, but investigations are under way to find ways to mitigate any toxicity-related issues.

As is so often the case, there is no silver bullet, and all three solar cell technologies are likely to coexist in separate niches that play to the strengths of each approach.

Despite their high cost and difficult manufacturing, silicone-based solar cells are established and will probably remain in use.

Once the challenges over the lead content in perovskite solar cells are solved, they could well become the default source of solar power.

And dye-sensitised solar cells will be chosen for their aesthetic beauty, low cost, and functionality. This technology was recently used for the first time in Lausanne, where a new conference centre was equipped with a 300-square-metre solar facade.

Mohammad Khaja Nazeeruddin is a senior scientist at the Laboratory of Photonics and Interfaces at the Ecole Polytechnique Federale de Lausanne in Switzerland, World Class University Professor at Korea University, Seoul, and adjunct professor at King Abdulaziz University, Jeddah.