The Microscopic Rakes that Boost Solar Cell Efficiency

Microscopic Rake - Solar Panel

Since solar panels became commercially viable for producing much needed and cleaner electricity, we have been working hard to find cheaper and more efficient ways of harnessing the power of the sun. The latest development comes from Stanford University in the United States where they have found that the introduction of microscopic rakes on light harvesting polymer-based cells can improve efficiency significantly.

“This could well be one of the most important developments we have seen in solar cell technology in recent years.”

The research has been led by Professor Zhenen Bao, a chemical engineer who works in the Materials and Energy Science Department at Stanford. Although not yet at the commercial manufacturing stage, this new research could see us change from more expensive silicon cells to cheaper polymer-based ones that have, up until now, suffered from an efficiency problem.

The Problem with PV Solar

Whilst silicon solar cells are more efficient, they are also a lot more expensive to make, taking some five years to produce enough electricity to offset the initial manufacturing cost. Polymer cells are cheaper and quicker to produce but have the disadvantage of not being as good at producing electricity.

Smaller polymer cells in the lab have produced efficiencies of up to 10% in laboratory conditions but when the technology is taken out into the wider world these levels have tended to drop considerably. Whereas a commercial polymer solar panel will have an efficiency of around 5%, silicon can provide electricity production up to and above 20%.

The potential for polymer cells is quite high as they are also more flexible than silicon cells. For instance, there are versions that can be painted onto conductors and which can be produced at a fraction of the cost of other solar cells. The sky is the limit if scientists can just come up with a more efficient level of electricity production.

How quickly this current microscopic rake development goes from research to the factory floor is a problem that most renewable technology faces, but according to Bao:

“The fundamental scientific insights that come out of this work will give manufacturers a rational approach to improving their processes, rather than relying simply on trial and error. We also expect this simple, effective and versatile concept will be broadly applicable to making other polymer devices where properly aligning the molecules is important.”

Finding more efficient ways to produce electricity through solar cells is one of the key factors for renewable energy development on the international stage. Long thought of as the prime research and development arena for new and sustainable technology, a lot of money in the last few years has been put into finding cheaper alternatives to the silicon solar cell.

Along with this drive to find something that can be manufactured and produced at a lower cost is the desire to also reduce the level of toxic waste that is often produced in the manufacturing process. Polymer-based solar cells may offer this opportunity to the industry and help it get over one of the major hurdles that detractors often cite  – namely that solar power is not as green as it pretends to be.

With governments being squeezed on budgets and funding and subsidies starting to wane, particularly in the UK, the need for a more viable and cheaper alternative to silicon solar cells has never been greater. The microscopic rakes in Stanford might well be the answer, but we will have to wait some time before they reach the factory floor and subsequently, our rooftops.

The Tidal Fence that Works in Shallow Water

Transverse Horizontal Axis Water Turbine

It could well revolutionise the way we harness the power of the sea and even some of our larger rivers. A new tidal fence development planned for the Bristol Channel, a snip at just over £140 million, shows how we are beginning to surge ahead with this particular renewable technology.

Having long taken a back seat compared to main stream approaches such as solar and wind power, the development from Kepler Energy (via Oxford University’s engineering department) marks another, positive step forward. The initial installation could provide as much as 30 megawatts that would supply power for some 30,000 homes.

The great news is that the technology is flexible and durable enough to be used in much larger constructions if this single experiment is a success. The Bristol Channel project is set to be approximately 1km long but there is no reason why we shouldn’t see extended tidal fences that stretch over 10km and eventually provide power for over a quarter of a million homes.

Think of a water mill underwater and you won’t be far off the mark when you try to understand how the system works. Its full title is the Transverse Horizontal Axis Water Turbine and the benefit of the technology is that it can sit in much shallower water than other devices that have been developed to harness the power of our coastline.

Kepler Energy was formed in 2010 and came out of research and development by scientists at Oxford University who have, in part, been financed by the Technology Strategy Board. The tidal fence is important because it can be deployed in small units and has a large potential for utilising the power of tides at low levels.

According to their web site, this different approach to tidal power could

“be used in benign sea conditions in a location closer to end-demand and which could generate utility-scale quantities of power.”

In the past, research has treated tidal power a bit like wind power, with the use of large, turning turbines that create the energy for electricity production. The team at Kepler Energy started by incorporating a better understanding of the ways in which the movement of air and water are subtly different and how we can find alternatives for producing electricity.

One of the major hurdles the scientists had to overcome was to create tidal fence that was strong enough to cope with heavy currents and could be readily duplicated. The tidal energy industry has had its problems over the years, not least in getting investment into technology that is often expensive to test and implement, particularly at the research and development stage.

Should the tidal fence in the Bristol Channel prove successful then we could start to see a genuine growth in this type of renewable having a genuine impact on our national power supply. We are already looking at the development of a tidal lagoon in Swansea Bay which has just been given the tacit go ahead and will cost in the region of £1 billion.

Whilst a validation report is still to be completed for the Swansea project and there are concerns about the environmental issues, it seems that development in the south east of the UK is focused strongly on how we can finally utilise the power of the waves.

Government Proposed FIT Subsidy Cuts

BayWa re Commercial Solar PV

The recent announcement on proposed subsidy cuts from Energy and Climate Change Secretary Amber Rudd forms part of a consultation process. Whilst she praised previous subsidy support for significantly driving down the cost of renewables, Ms Rudd added:

“As costs continue to fall it becomes easier for parts of the renewables industry to survive without subsidies. We’re taking action to protect consumers, whilst protecting existing investment”.

All the proposed changes appear to have done so far is heap uncertainty on to the development of both ground-mount and rooftop mounted solar PV projects.

Many companies in the still nascent UK solar PV industry are understandably very concerned by the proposals being made. Those companies that have previous experience of Government involvement in our industry know all too well that although they appear to be part of a consultation process, the intentions of the Government are pretty clear-cut – they intend to cut back on spending in the renewable energy industry.

Many concerned parties are questioning the timing of the announcement immediately after the House of Commons has risen for the summer recess, as proper parliamentary scrutiny cannot now take place until after the deadline for the consultation process passes.

The measures announced will raise more questions for potential investors in low carbon, renewable technologies, many of whom are already struggling to finance projects after a series of knee-jerk policy changes. These latest changes only undermine current levels of certainty for the lowest cost renewable technologies and inevitably fail to provide any indication of the future investment potential.

The main impact for consumers and the PV industry as a whole will also be one of confidence. The economics of solar PV are already strong, but there is still the need for Government incentives to remain in place for one or two more years in order to get to the Holy Grail of energy parity. This is where the cost of electricity generated by PV is equal to or less than that of conventional energy.

Solar PV is already cheaper than most other forms of renewable energy and can be deployed almost immediately. Announcements like this only confuse the message associated with the technology. In 2011 consumer research showed that the majority of the public were of the opinion that solar PV support (namely the Feed-in Tariff) had been switched off by the Government, when in fact that conditions soon after provided similar rates of return for smaller capital outlay.

It is hard to say at this stage what the impact will be on the industry as a whole. Solar PV equipment costs had already fallen significantly and frankly global influences on the price of PV make anything the UK does insignificant in terms of policy change.

The most significant impact will be that the UK will once again fall behind its peers in the deployment of renewable energy and the development of a green economy. Valuable skills will either be mothballed or lost to the industry until a more progressive less short-sighted administration returns to power, something we know is not likely to happen for at least five years.

The Solar Trade Association is in the process of outlining a number of steps that need to be taken in order to ensure the PV industry becomes self-sufficient after subsidies digress and eventually end.

The potential conflict between the PV industry and the UK government however lies with the politics of power. The predicted savings of around £10 per a year on each customer bill is surely a price that most UK power consumers would be willing to pay for the benefits of a cleaner, more independent energy structure? We can only hope that the consultation process actually involves consultation and that common sense prevails.

Ian Draisey
Ian Draisey



An opinion piece from Ian Draisey, Managing Director, BayWa r.e. Solar Systems Ltd.



About BayWa r.e Solar Systems Ltd BayWa r.e. Solar Systems Ltd is one of the UK's leading wholesale suppliers to the solar PV installer network. Head-quartered in Machynlleth, mid-Wales and operating across the UK and Ireland, BayWa r.e. is an approved ISO 9001:2008 company for the procurement and supply of high quality products for solar PV applications. As part of the German BayWa r.e. renewable energy GmbH group of companies, we offer competitive pricing with direct access to Europe-wide stocks of high quality, high profile solar PV brands and products.



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