The Low Carbon Kid: Just two years away: cheap, easy to make, 3rd generation solar cells

Thursday, February 11, 2016

Just two years away: cheap, easy to make, 3rd generation solar cells

In 2018, the long-promised “third generation” of solar cells will be ready to come to market. These are very different from the solar panels we see around us today. Transparent, lightweight, flexible and highly efficient, they will be able to be applied to windows, metal, polymers (as in cladding) or cement, effectively turning buildings into energy generators.

They can work in lower light conditions than current solar technologies, and don’t have to face the sun.

The technology is known as perovskite solar cells. Recently, a research team headed by Professors Michael Grätzel and Anders Hagfeldt at the Ecole Polytechnique Fédérale de Lausanne established a new world record efficiency for the cells, with a certified conversion efficiency of 21.02 per cent, increasing from 3.8 per cent in 2009, making this the fastest-advancing solar technology to date.

With low production costs, many start-up companies are promising modules on the market by 2017.

Dyesol Limited is one such company focused on commercialising these cells. Dyesol has been around for many years, longer than most of its competitors, and has secured several key patents in the field.

Three years ago it switched its research and development from dye-sensitised technology to perovskite because of its advantages.

Based in Australia, its chief executive, Richard Caldwell (above), recently released a levelised cost of energy study (which enables comparison with the market price of other energy technologies). This demonstrated costs of between 9.6 and 12 Australian cents per kilowatt-hour for the panels when manufactured and utilised at a relatively small scale. This compares to around 10-11 cents for conventional solar – about the same, but before mass production.

At the end of last year Caldwell reached an agreement with the Australian Renewable Energy Agency to receive $450,000 funding support to progress the technology towards scalable manufacture and mass commercialisation. ARENA has established a production cost of 25 cents per watt.

“The payback period for installation is a matter of a few months, as they are less energy intensive to produce than the current (usually silicon based), which take several years,” Caldwell says.

“This is extremely exciting, as it allows us to transition to a clean energy society without any subsidies from the government.

“BIPV – building-integrated photovoltaics, in other words putting solar power generation on the surface of buildings – is the holy grail of the industry and because perovskite is ultra-thin it can easily be incorporated in buildings,” he said. “But that’s longer term. We will first produce a free-standing unit for market entry, then integrated.”

The company publishes quarterly updates of progress to demonstrate progress. Caldwell says that its next landmark later this year is “the production of panels about one metre square”, with countries like Turkey partnering to produce them.

“By 2018 we hope to be in mass production of this new product.”

The first product will feature a glass substrate, allowing light through to the interior of the building. The following year, metal-printed panels will be on the market, the company says.

Australian support

Dr Richard Corkish, chief operating officer at the Australian Centre for Advanced Photovoltaics, which has been responsible for many of the improvements in silicon solar panels the world uses today, told the ABC: “Most of the important advances in solar cell work in the past has been in making incremental improvements on the same old technology that [was] invented way back in the 1950s, but [is] now much, much better.

“[Perovskite] has captured the excitement of the whole photovoltaic research community. This material might in the future offer an alternative to silicon for the main solar cell material. Our research partners – Monash University and the University of Queensland in particular – are at the forefront of this area in Australia.”

Caldwell says “the new political regime in the Australian government is more favourable to us and the Turkish government is also very supportive.”

He welcomed Bill Gates’ recognition of the technology during the Paris climate talks, when Gates joined 27 other wealthy investors to start a new investment fund called the Breakthrough Energy Coalition, to push more public and private sector funds to clean energy technology.

Gates called PSC “disruptive” and said: “When people start talking about perovskites, painted solar applications etcetera, a lot of it is down to the physics, so the majority of the money will flow through the fund.”

The technology

The most commonly studied perovskite absorber is methylammonium lead trihalide, which uses a halogen atom such as iodine, bromine or chlorine.

Unlike traditional silicon cells, which require expensive, multistep processes conducted at high temperatures (>1000 °C) in a high vacuum in special clean room facilities, the organic-inorganic perovskite material can be manufactured with simpler wet chemistry techniques in a traditional lab environment.

Methylammonium and formamidinium lead trihalides have been created using a variety of solvent techniques and vapour deposition techniques, both of which have the potential to be scaled up with relative feasibility. These techniques reduce the need to use so much polluting solvents.

Issues yet to be resolved are around stability, as the material can degrade, reducing its efficiency.

Dyesol is developing and testing this. Its most recent newsletter, published last week, announced that a test strip passed 1000 hours at 85°C with a loss of under 10 per cent. That is still a lot, so work is underway to reduce this deterioration with different types of encapsulation. To be fair, early silicon panels suffered from a similar problem.

A related challenge is cheap and environmentally friendly electricity storage, enabling solar electricity to be used also at night.

But for now, having been heralded for a long time, very cheap solar power that lets every building or object coated with it generate electricity is now within reach.