There are a number of companies involved in using printing, or printing like processes to manufacture batteries and photovoltaics. NanoSolar has announced the building of large scale plants in both the US and Europe to produce photovoltaic cells using a process akin to ink jet printing. It is reel to reel on flexible substrates. This is a so-called CIGS technology- copper indium gallium diselenide - but G24 Innovations in the UK is also using an ink jet type of reel to reel process to make DSSC - dye sensitized solar cells. These also form part of the new generation of photovoltaics beyond yesterday's heavy, rigid, silicon constructions. Konarka is also a leader in the production of photovoltaic cells on flexible plastic film. Recently, it has also announced some major advances and partnerships, for its organic photovoltaics, yet another post silicon option that has the new advantages of flexibility, light weight, low cost and more. Some of the new generation solar cells even generate electricity from heat when there is no light available.
Power Power, Solicore, Thin Battery Technology, Enfucell and many others are currently using printing processes to manufacture thin flexible batteries and even paper forms part of some of these constructions, improving cost and environmental credentials. Low cost versions are usually carbon zinc (sometimes known as manganese dioxide zinc) and the higher cost, better performance versions are usually based on lithium. Like the photovoltaic companies, many of these companies have recently raised tens of millions of dollars or more to get into mass production.
Clearly, the time is right for printed photovoltaics and batteries and, in some cases, they will even be printed at high speed on top of each other, so energy harvesting can occur where the photovoltaics gathers energy when it can and stores it in the battery for delivery when it is needed. Optimal coupling of different printed components is becoming a focus of attention as all these technologies move firmly into the marketplace. Sometimes both the battery and the photovoltaic cell are transparent, so they can be used on the face of the watch or a window for example and provide smart packaging with no stealing of space needed for promotional and instructional messages and graphics.
Photovoltaics beyond silicon
Demand for power is skyrocketing - as the world's population continues to expand, the developing world rapidly industrializes and more and more everyday devices, systems and structures go digital. Thin film photovoltaics, using inorganic or organic compounds as active layers, represent the most promising technology for significantly beating the cost of conventional solar amorphous or crystalline silicon electrical systems - both up front cost (including transport and installation cost) and cost per watt. These technologies have the potential to provide low cost, ac mains solar power by using non-silicon solar cells and low cost plastic substrates. Traditional silicon cell manufacturers have been constrained by the shortage of silicon, high prices of silicon, its weight and fragility and the difficulty of processing it. Despite this, silicon is the dominant semiconductor material used in present day solar cells, with over a 93% market share, due mainly to its maturity and huge government subsidies in countries such as Germany, the world's greatest user of solar energy. That situation is now changing.
The benefits of non-silicon photovoltaic materials are many and varied. Some generate electricity at narrow angles of incidence and even with polarized (e.g. reflected light). Beyond silicon, there are a number of technologies being commercialized including those compared in the table below.
Types of printed/thin film photovoltaics beyond silicon compared, with examples of suppliers
Thin film Cadmium Telluride (CdTe) photovoltaics has attracted over one billion dollars of business in 2007 for delivery over the next few years and CIGS photovoltaics has led to the most factories being built and it has attracted the largest number of researchers. However, DSSC has its own combination of benefits and limitations so it will carve out a different, large market.
Organic alternatives to the inorganic compounds in these photovoltaic devices have been the least efficient, but work has continued with them partly because they may eventually be lower in upfront cost and cost of ownership, where space is not a problem. Indeed, some researchers believe that organic efficiencies may eventually match the competition. Very high speed printing of very thin flexible organic layers - wide area but cheaper nonetheless - has been one dream. Conventional solar cells cost $2.3 to generate one watt of electricity compared to $0.1 promised for the latest organic cells. It may take ten years for silicon to reach $1 per peak watt but that is promised far sooner for the alternatives.
Huge market after a slow start
The first multibillion dollar sales of all types of printed electronics are photovoltaics. IDTechEx find that the market for thin film photovoltaics beyond silicon will reach at least $1 billion in 2012 after a slow ramp up and grow rapidly after that to $6 billion in 2014. The global solar energy market is expected to reach $34 billion in 2010 and $100 billion in 2050 and most of that latter figure will be achieved by non-silicon photovoltaics. The market for printed batteries will reach $170 million in 2012 and $560 million in 2014.
Trends by territory
When we count the number of interested organizations, Europe is the leader in printed and thin film photovoltaic development with a broad platform of R&D institutes, small start-ups and large companies. In particular, energy conscious politicians are driving development through large subsidies of both manufacture and installation. Major political decisions are about to further increase both the awareness and the broad use of photovoltaics in Europe. In Italy, beginning this year, every new house has to use solar energy - thus creating a huge market for all kinds of technologies, photovoltaic as well as solar-thermal.
The following diagram shows the IDTechEx estimate of the number of companies and research organizations involved in printed and thin film photovoltaics by territory. However, this disguises the fact that, in East Asia, the companies involved are, on average, larger than elsewhere - for example, Sharp produces more MW of silicon based solar power panels than any other and Honda brought a new generation photovoltaic factory on line in 2007.
New IDTechEx Research
The comprehensive new IDTechEx report "Printed and Thin Film Photovoltaics and Batteries" by Dr Bruce Kahn and Raghu Das gives a thorough analysis of the subject. It covers the science and the manufacturing technology extremely thoroughly yet in understandable form. Future trends are identified and 34 tables, 84 figures and 234 references pull it all together with many comparisons of the good and the bad of the various options and forecasts for the future. Important parameters and their optimization are covered in detail. Materials - inorganic and organic - and device structures are thoroughly examined and compared as are the various forms of high speed printing employed. The report also describes several successful applications, including toys, cards, personal electronics and smart skin patches. Ten year forecasts are given. To learn more and view sample pages see www.idtechex.com/power.
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