Long the exclusive preserve of space engineers, isolated woodsmen and that eccentric family down the street, photovoltaic solar panels are about to come into the mainstream on the back of a new wave of research, experts say. At the University of Illinois at Urbana-Champaign, a team of researchers announced the discovery last week of a method to make clunky silicon-based solar panels thinner and more flexible, allowing them to be attached to the walls, even windows, of buildings.
At several universities in the UK, another team of researchers is developing highly flexible thin-film photovoltaics produced from cheaper materials that they hope will put solar panels within reach of the average consumer. Ken Durose, a professor of physics at the University of Durham who is part of the PV21 project, says a colleague is now working to develop material that was only one fifth of one millionth of a metre thick. By using less materials, the team hopes to mass-produce panels at a fraction of their current cost.
Both kinds of photovoltaic research are being pursued at institutions across Europe and Japan as interest in solar crests to unprecedented levels. The industry is in the midst of "an acceleration of an acceleration", Prof Durose said. Photovoltaic solar panels convert sunlight directly into an electric current, cutting out the need for steam or gas turbines. Solar proponents often cite the statistic that if all the energy of sunlight striking the earth for 40 minutes were successfully captured and stored, it could meet human energy needs for an entire year.
The challenge, however, has long been how to convert that sunlight into electricity efficiently and cheaply. For a long time, the biggest impediments have been the high cost of panel materials and low levels of conversion efficiency. Conversion efficiency measures how much energy is converted into electricity from the power source, whether coal, sunlight or wind. Producers of photovoltaics have struggled to achieve 10 per cent efficiency levels in commercial-scale production, whereas the most efficient natural gas plants can achieve efficiency levels of more than 50 per cent.
Low efficiency levels have been compounded by the fact that the first generation of single-cell solar panels were developed from expensive semiconductor materials - often a mix of silicon and rare metals - which limited their availability. But this week's announcement from the University of Illinois indicates scientists have found a way to slash the amount of semiconductor required in conventional solar cells.
Researchers led by Prof John Rogers developed a method to shave off extremely thin slices of silicon wafer and roll them onto a second material. The slices are 10 to 100 times thinner than the wafer, and the final material is pliable enough to be rolled around a pencil. The material is also thin enough to be nearly transparent. "It opens up spaces on the fronts of buildings as opportunities for solar energy," Prof Rogers told Reuters.
As scientists continue to pursue research into conventional silicon cells, a second group of researchers is working to improve the efficiency of a separate group of solar materials called thin-film solar cells that are made from a whole different class of materials. Prof Durose noted that the thin-film cells were distinguished by their "inherent cheapness". The trade-off, however, is that thin-film materials generally achieve lower efficiency levels than single-cell silicon, because the tiny boundaries between crystal grains block efficient absorption of sunlight.
Prof Durose said he was focusing on minimising the loss of energy and raising efficiency to acceptable levels. He noted that scientists in a laboratory had succeeded in achieving efficiency levels of 16.5 per cent with cadmium telluride, one of the cheapest solar cells available. The developments on both fronts mean photovoltaics are within commercial reach, Prof Durose said. The European Photovoltaic Industry Association says solar could supply 12 per cent of Europe's energy needs by 2020, a target Prof Durose said was realistic, if research continued to push down costs and subsidies helped bridge the gap in the medium term.
"In the next 10 to 20 years, we hope to see the cost reduce so that it's comparable to grid-connected power," he said. "At present, the cost of solar energy is many times grid-connected." In December last year, Scientific American Magazine put forth a plan to invest US$400 billion (Dh1.46 trillion) in the next 40 years in solar power, which they envisioned could supply 69 per cent of the country's energy needs. The magazine's editors argued that the main impediment was the low efficiency of photovoltaic panels - researchers had to achieve efficiency levels of 14 per cent to make solar viable, they estimated.
With oil prices at record highs, interest in alternatives is booming. The US, Germany and Japan remain key places for solar research, but new centres of research are emerging quickly, including the Abu Dhabi Future Energy Company (Masdar), Prof Durose said. Solar proponents have long sketched out a dream of solar panels coating the surface of the urban landscape, generating power without pollution. Recent breakthroughs indicate that dream is now within arm's reach.