Solar Energy Harvesting: Is scaling up the only way forward?

Focusing on Copper Indium Gallium Selenide (CIGS) photovoltaic technology, some of the most promising examples of venture backed companies have run into troubles (e.g. Nanosolar's issues with scaling up production) with some of them failing to meet expectations (e.g. Solyndra's closure last year) in a very public manner.



However, others have managed to succeed and the most striking example of that is probably Japan's Solar Frontier that managed to close 2011 in a spectacular way, increasing production to almost 600 MW (starting at less than 50MW in 2009 and reaching just under 80MW in 2010). This makes them the second largest thin-film module company, behind the 2GW of modules that were shipped by First Solar in 2011.



Performance and Cost



Solar Frontier's thin-film modules achieve over 12% efficiency, a bit higher than First Solar whose cadmium telluride modules are currently at just under 12% efficiency. That's still quite far from the efficiencies of up to 22% achieved by mono- crystalline silicon vendors but the company is already aiming for higher efficiencies, targeting 14% by 2014.



The firm has not disclosed cost-per-watt figures as of yet, which probably means that their manufacturing costs are still relatively high when compared to established silicon module manufacturing or First Solar's very low cost per watt levels achieved. Comparing to historical data from other companies, economies of scale will help bring costs down dramatically for Solar Frontier and will make the company's modules increasingly competitive.



This will create a more difficult situation for other thin film manufacturers that have yet to achieve large volume production who will have to offer a competitive product if they want to succeed.



Humble beginnings



Some companies on the other hand have decided to take a different approach to commercialization of their technology. Dye Sensitized Solar Cell (DSSC) technology companies such as G24 Innovations and SolarPrint are looking into application in the wireless sensor space, a market that's forecasted to grow dramatically in the next few years. Starting with more humble applications such as meter reading in buildings, wire sensor networks alone will grow rapidly from $0.45 billion in 2011 to $2 billion in 2021. These figures refer to WSN defined as wireless mesh networks, ie self-healing and self-organising. The market for wireless sensor systems in general is far larger and some proposed standards apply to both. IDTechEx's Energy Harvesting & Storage and Wireless Sensor Networks & RTLS conference in Berlin, on May 15 and 16 this year will focus both on wireless sensors as well as the photovoltaic and other harvesting technologies that are being integrated and are creating exciting new market segments for solar cells.



Other companies, like Konarka, Dyesol and Ascent Solar are also looking into solar integration into portable devices, from vehicles giving photovoltaic functionality to mobile phones, tablets, solar bags, through to car roofs and windscreens. These markets are not as large as the markets for rooftop and solar farm installations but of course, the competition there is not as harsh. As an added benefit, some of the requirements of these applications might be more relevant to some of the thin film technologies as they are characterized by unique advantages that could make them a preferred choice. Examples include improved indoor performance, transparency, and even improved power production at wide angles of incident light.



By Dr Harry Zervos, Technology Analyst