Solar cells – photovoltaics

Anyone reading the scientific press over the last year or so will have seen huge publicity given to the millions, if not billions, that are being spent on photovoltaics.  Much of the money is raised through venture capital but governments are also helping with things like buy-back tariffs that allow any excess electricity to be sold to the electricity companies at a financially attractive rate.

The result of all this money has its good points and bad points for the vacuum coating industry.  The vacuum system manufacturers are happy because most, if not all, have full order books.  This may not be as good for vacuum system buyers as this leads to longer lead times for system delivery and less requirement on the manufacturers to bargain over prices.

This delivery delay has also brought opportunities for companies who have not previously built roll-to-roll coaters to enter the market. I know of several who have seized this opportunity to promise an early delivery, compared to the established manufacturers, to secure an order.  This also has the perceived advantage of secrecy as some manufacturers have several orders and so potentially are building machines for customers who will be competitors.  This is no different to the established metallizing industry but within photovoltaics there is a level higher paranoia about intellectual property that obviously causes some purchasers ulcers in worrying if something, they think is proprietary, is going to be disclosed elsewhere.  Time will tell if these system manufacturers that have now built their first roll-to-roll coater will now start to offer metallizers and so offer more choice and possibly bring back pricing pressure.

It is not only the system manufacturers who are benefiting but also the other suppliers. This has the effect that it increases the lead time on some components which also has the potential to lengthen the build times as well as delaying repairs or maintenance.

When reading the press there are frequent claims for world record performance cell efficiency.  Often the reason for trying to get the ‘world record’ is to get the publicity to help get the venture capital funding.  However it is worth noting that often the sample that is tested may only be 10mm square and some also include layers such as an anti-reflecting surface to get every last bit of efficiency out of the sample. The samples may also be produced in static vacuum deposition systems and so it is probably not surprising that, in transferring the static process from the 10mm size to a dynamic wide roll-to-roll process, the efficiency takes a dive.  To recover the efficiency takes time, sometimes years and it is a race because competitors are doing exactly the same.  What is not included in the ‘world record’ efficiency test is anything to do with the lifetime of the cell.  Once the cell is produced it need to have contacts attached and then the whole thing needs to be protected.  Silicon solar cells have extended lifetimes from 15 years to 25 years and there has been talk in extending this further into 30+ years.  So for these newer designs of cells there is an expectation that they will have to have long lifetimes. This may not have to be as long as for silicon cells as the production costs are lower the payback time will be much shorter.  Even so the cells will have to be effectively protected by a barrier material. This presents a huge opportunity for some of the newer barrier materials that have a performance similar to those required by the display industry.  These are sometimes referred to as ultra barrier materials.  Several of these barrier materials have been promised but none are available in large quantities.  Most of these materials include some vacuum deposited layer and so this too can be expected to provide more orders for roll-to-roll vacuum coaters adding to the already full order books.  For those who are looking to produce ultra barrier type materials this additional high volume market just adds to the incentive to overcome the production difficulties in producing the necessary high quality barrier material.

There may be questions about whether the boom will last and the answer is yes although it will not be consistent.  Some solar companies will fail and this will put some second-hand machines onto the market. Just how many companies fail will depend on the demand for cells and the patience of the venture capital backers.  The market gurus claim that we are heading for a world over capacity of cells as all the different investments start producing material and that this will last for several years. Thus some of the predicted machine requirements may be delayed or cancelled. 

So despite the financial doom and gloom that is being written about elsewhere things are generally positive in vacuum deposition system building.