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“The man with no trousers learns to carry his wallet in his bumcrack.” It’s fair to say that British inventor James Dyson is nothing if not concise – a talent that helped him distill 5,126 failed prototypes into a revolutionary bag-less vacuum cleaner that spawned a billion-pound business empire. But today we want to ask him not about dust – or the optimum way to carry one’s wallet – but solar power.

It’s a subject that both fascinates and frustrates him. “Nobody has worked out how to harness the power of the sun effectively,” he points out. “Since the invention of photovoltaic cells in 1954, it is only in the last few years that they have begun to show signs of fulfilling their promise.”

And what promise. Every 40 minutes, enough solar energy hits the United States to power the whole country for a year. And yet while harnessing this energy may be predicated on the same principle that powers a pocket calculator or digital watch, the next-gen solar cell that could power your house, your town or your city, bears little resemblance to the silicon cell in the average roof installation.

The race to improve efficiency

Tucked away in Oxford, Sharp Labs of Europe are racing to help fulfill the promise that Dyson envisions in their research and development laboratories, developing solar cells using compound semi-conductor materials and nanotechnology. “We’re researching the next generation of solar cells, and endeavoring to make a big leap forward in their efficiency,” explains Jon Heffernan, director of Solar research at Sharp Labs. “Right now, we’re working towards solar cells with a 50% efficiency – but in the future that could be up to 70% efficiency, depending on which theory you believe.”

Efficiency is the key to creating the kind of solar installations that could power a whole country. But currently, the highest proven cell efficiency is 36.9%  - a world record announced two weeks ago by Sharp. To put that in context, the average rooftop solar panel has an efficiency of 14% – in other words, the efficiency with which the cell converts the power of the sun, measured in watts, into electricity.

“Good technology should solve problems” says Dyson. “Existing PV cells are heavy and only have limited applications. The technology should better fit into its surroundings, so you don’t even notice them.”

While the current technology works, Heffernan believes the future lies in Sharp’s R&D labs. “There is development towards what we call building integrated  PV – making the module more integrated in the roof – such as solar tiles. Or the PV forming part of the structure of the roof rather than merely bolting it on. Of course, it then has to function as part of a roof than a solar panel so it needs to meet building regulations. But it’s certainly something we’ll see in the future. Sharp also sees the solar module as becoming part of an overall energy solution for the homeowner. Technology will enable the home owner to be self-sufficient and manage the generation and use of Solar power in the home. This is the big vision.”

The future for solar power

The most exciting prospect for solar power is nanotechnology PV material that can be printed onto a flexible substrate – opening up the possibility of coating gadgets like smartphones or tablets in PV film that collects and stores solar energy. “Products that are totally green are elusive and, currently, PV cells used in a phone will not generate enough energy to compensate for what it takes to manufacture” says Dyson. “But engineers in France have developed a transparent photovoltaic film that absorbs light. The transparent film doesn’t impair the use of the screen and whilst it’s too early to comment on the technology, it presents the prospect of charging a mobile phone in six hours. This new development also means it can be powered with indoor as well as outdoor light and the thin film is lightweight. There are a number of applications for the film; it could cover an entire roof without issue.”

Payback time: Is it still worth installing solar panels?Solar expert Jon Heffernan says: “A typical module that goes on a rooftop generates 180watts of power,  and a typical rooftop would be around 16 modules, which would generate 3 kilowatts. The government provides a payment if you put a solar cell system on the rooftop, it will pay you for each unit of electricity you produce. Up till now, that payment has been 43.3p per kilowatt hour, so a typical installation has a ‘payback time’ of 8-9 years. The subsidy has been halved, thus the payback time for the average installation has doubled to around 16 years. But, the subsidy is guaranteed for 25 years – and the modules will last 25 years. So the system will still pay for itself – and generate free electricity. It’s part of the country shifting to sustainable energy, to stimulate people to move towards renewable energy. The more people invest, the more the cost of the panels will reduce and the more jobs we will create in a strong renewable energy industry.”

“But in the medium-term, it comes back to efficiency,” says Heffernan. “If we can develop low cost cells, then it becomes much more attractive – and that’s the purpose of our research and development. It will move from the rooftop to consumer goods like mobile phones. At the moment, solar cells on phones provide a trickle charge, but when you improve efficiency, they will power a phone just like a modern charging dock would – even indoors under household lighting”

The tipping point

Sharp Labs is already working on a a number of materials to reduce the cost of the cell,  using nanotechnology to provide high efficiency and low cost. Part of the aim is to develop a low cost method of delivering that  material –  using printing technology or depositing them via chemical, on various flexible substrates. “Then there are quantum dot materials,” reveals Heffernan.

“The nano scale of the tech has two effects – it can create new physical properties that make the cells more efficient, and with materials on that scale, you can spray them onto a surface. There’s a tipping point when it becomes attractive to the consumer – when a solar cell can generate enough power to power my phone, or be integrated into the roof of a car and power the air conditioning without increasing the cost of the car.”

But back to the present. The recent news that the government is to halve the ‘feed in tariff’ paid to homeowners who install solar panels has resulted in a rush to complete installations. Will it still be worth investing in solar panels after the tariff is cut?  “Ok, there are two aspects to this” says Heffernan. “Financial and eco. Looking at the financial side, the recent reduction of the government’s feed-in tariff has made it less attractive to invest, but the overall cost of modules is expected to go down. So although a typical system may now pay for itself in 16 years rather than eight, it’s still worthwhile. And once the system does pay for itself, you will be generating free electricity. Then in terms of the eco aspect, both nationally and as individuals we need to move to renewable energy. Not only does it contribute to the global need to reduce our reliance on non-renewable energy sources, but self-sufficiency will give you more autonomy. In the long term, it makes perfect sense”.

Or, as Dyson puts it: “With energy costs spiraling, they are a wise investment for the future”. Like we said, he’s nothing if not concise…

                                                                                                                                                                         

The James Dyson Award is an international student design award running in 18 countries. It’s run by the James Dyson Foundation, James Dyson’s charitable trust, as part of its mission to encourage the next generation of design engineers to be creative, challenge and invent. To see the 2011 winner, and the 2012 dates simply click here.

Image credits

Sir James Dyson by Paul Toeman at the 2009 Conservative Party Conference.