Solar-cell method punted as new-energy breakthrough

23rd January 2009 By: Guy Copans

A simple solar-cell method being developed in the UK could provide as much electricity as that produced by 50 wind turbine farms.

UK Trade & Investment publication Trade with Britain says that scientists are developing this new ecofriendly technology, after having investigated ways of painting photovoltaic (PV) cells onto the flexible steel sheeting and surfaces commonly used for cladding homes, offices or buildings.

Unlike conventional solar cells, the materials being developed at Swansea University, in Wales, are more efficient at capturing low-light radiation. Paint is applied to ordinary steel cladding when it is passed through rollers during the manufacturing process.

The researchers believe that the same approach could be used to build layers of the solar-cell system, with the aim of producing cells that can be painted onto a flexible steel surface at a rate of 30m2 to 40m2 a minute.

"We have been collaborating with the steel industry for decades but have tended to focus our attention on improving the long-term durability and corrosion resistance of the steel, " says Dr Dave Worsley, a researcher in the materials Research Centre at Swansea University' School of engineering.

He says that, until now, improving the aesthetic look of the outside of steel has been the only research focus, without any focus on other potential capabilities. He says that one of the university's engineering doctorate students researched how sunlight interacts with paint and degrades it, which led to the university developing a new PV method of capturing solar energy.

The success of the study had led to the award of a three-year project worth more than R23-million by the UK'S Engineering & Physical Sciences Research Council. Swansea University is now leading a partnership with Bangor University, the University of Bath, and Imperial College of London to develop commercially viable PV materials for use within the steel industry.

Worsley maintains that the potential for the product is immense. "Corus Colours (manufacturers of pre-finished steels), produces around 100-million square metres of steel building cladding a year. If this was treated with the PV material, and assuming a conservative 5% energy conversion rate, then we could be looking at generating 4 500 GW of electricity through the solar cells annually, which is the equivalent output of roughly 50 wind farms," he says.

Worsley will be working closely with Corus to research practical, cost efficient methods of mounting the system on steel structures, with the possibility of the eventual commercialisation of the product.

According to UK journal New Scientist, the new PV paint will be based on dye-sensitised solar cells. The report notes that instead of absorbing sunlight using silicon like conventional solar panels, these use dye molecules, attached to particles of the titanium dioxide pigment used in paints.

It says that this provides an energy boost to electrons, which hop from the dye into a layer of electrolyte. This then transfers the extra energy into a collecting circuit, before the electrons cycle back into the dye. New Scientist adds that while they are less efficient than conventional cells, dye-based cells do not require expensive silicon and can be applied as a liquid paste.

Worsley describes the innovation as a collision between two existing technologies, one for generating electricity, and the other for applying paint to steel. He predicts that a commercial cell could be realised within two-and-a-half years.

The layers of the solar cells comprise, firstly, a barrier of normal paint laid directly onto the steel, then electrolyte and dye layers, followed by a clear protective film to guard against the elements.

The team has successfully painted small demonstration cells onto steel, and are working with colleagues at the partner universities to improve the performance of the different layers.