Dye sensitized solar cells: third generation photovoltaics | Energy Harvesting Journal

Third generation solar technologies such as dye sensitized solar cells are expected to usher a new era of added functionality and lowered costs, adding to the overall value proposition of solar power generation. In the short term, incumbent technologies will outperform emerging solar cell platforms, both in terms of performance and cost structure due to economies of scale achieved. Hence, developers of DSSCs will need to identify niche markets that will allow for seeding further growth in later years. Detailed drivers and market forecasts by IDTechEx’s technology analyst Dr Harry Zervos are described in the report “Dye Sensitized Solar Cells: Technologies, Markets & Players 2012-2023” (www.IDTechEx.com/DSSC ).

Introduction

The advent of 3rd generation solar cells relates to their potential for reaching even lower costs than silicon and thin film platforms due to the usage of abundant, low cost materials and simple manufacturing processes along with added functionalities such as lower weight, flexibility, semitransparency etc. These added performance metrics can potentially enable the use of photovoltaics in new applications where rigid conventional cells would be unsuitable. Together with their cost reduction potential they will eventually offer solutions that can allow for further adoption of solar power generation but how quickly can this be achieved?

Performance limitations in 3rd generation solar cells

The main issues that 3rd generation PV technologies have to solve relate to performance limitations: in lifetime and efficiency. The champion efficiency map in figure 1 (for outdoor lighting conditions), compiled by the National Renewable Energy Laboratory in the USA clearly depicts the handicap in best performance achieved by DSSCs when compared to technologies that have been under development for longer and have achieved much better efficiency levels. On the other hand and on a more positive note, it’s also obvious that amorphous Silicon performance is not out of reach anymore and the gap in efficiency has closed dramatically in recent years.

Figure 1: Best performance achieved in research DSSC cells
Sources: NREL and IDTechEx

A worrying stagnation in champion efficiency developments in DSSCs was recently interrupted, with research led by Professor McGehee at Stanford University and published in Nature Photonics in March 2012 has demonstrated material and structural optimizations making it possible to obtain higher open-circuit voltages, leading to a record power-conversion efficiency of 12.3%.

A significant limitation for DSSCs remains the stability of these types of cells, especially when taking advantage of flexible form factors and not depositing on glass. Lifetime in some utilization scenarios is limited to around two years, a significant difference to the 25+ year lifetime guarantee offered by competing technologies. Glass deposited versions can actually achieve lifetimes over 10 years but degradation mechanisms relating to sensitivity to moisture, oxygen and in some cases light itself have posed a barrier in achieving lifetimes that are competitive with incumbent technologies.

Although DSSCs do not offer very high efficiency levels or lifetimes comparable to silicon or inorganic thin films, they can offer good form factor, better-indoor performance (as will be discussed in more detail in the next paragraph), the potential for low cost large-scale manufacture, and low capital expenditure.

Identification of niches, market penetration in the short term

Since it becomes increasingly hard to compete in rooftop and solar farm installations with other solar technologies, it is of the utmost importance for DSSC developers to identify segments where perceived benefits outweigh performance limitations. Superior low light performance in indoor environments (as demonstrated in figures 2 below), improved high temperature performances compared to traditional solar technologies, increased flexibility, semi-transparency, ease of manufacture are some of the advantages that can make a convincing case for 3rd generation technologies in specific applications.

Figure 2: DSSC power output in low level lighting conditions compared to amorphous silicon performance
Source: Solarprint

Indoor applications

The added benefits in indoor operating conditions have allowed for the commercialization of some of the first DSSC products, optimized for operation in the specific environments they will find themselves in. An interesting example is the Folio wireless keyboard launched in May 2012 by Logitech, exclusively powered by solar cells.

G24i’s solar battery system is also currently being used in conjunction with Skyco shading systems and BTX Motors at a major hotel chain in Las Vegas as part of their $50M renovation. The G24i/BTX/Skyco offering of solar powered motorized blinds is estimated to have saved the hotel over $3M in construction costs by utilizing the G24i solar technology.

Wireless sensors & wireless sensor network

The emerging market for wireless sensors and wireless sensor networks is of particular interest as well. Energy harvesting wireless switches and sensors can collect small amounts of energy from their environment. With the advent of ultra low power electronics many sensors can operate by harvesting very small amounts of light from their surroundings, enabling them to register, detect and transmit information wirelessly. These technical breakthroughs reduce the energy needed to transmit a signal. As a result, deployments of energy harvesting wireless sensors make applications feasible, while minimizing maintenance costs, enabling their operation in environments where other technologies (e.g. primary coin cells with their limited lifetime and need for frequent changing) are not suitable.
What’s interesting about this market space is that several different verticals would have an interest in DSSC enabled sensors and actuators, whether it’s in building automation, industrial automation and condition monitoring, in civil infrastructure or even in vehicles (from cars to ships to aircraft etc.). Companies such as SolarPrint and G24 Innovations are spearheading the efforts for adoption in this space, with collaborations with sensor technology and low power electronics developers in order to create prototypes and demonstrators that can showcase the possibilities opening through the use of harvester-powered wireless sensing/actuation.
More examples can be found in the IDTechEx report “Dye Sensitized Solar Cells: Technologies, Markets & Players 2012-2023” (www.IDTechEx.com/DSSC ).

Conclusions

As the interest in renewable energies grows, more applications are being identified and at the same time, new technologies developed lead to innovative devices with added functionality that lead to more sustainable production of energy. Whether it’s large scale installations or small-sized deployments, the overall advantages relate both to a cleaner, sustainable way of producing energy to cover ever increasing needs, but also, the realisation of projects and applications that were previously not possible.

Penetration of new technologies remains an arduous task which often needs to be supported by incentives, government mandates and insightful investment into technologies that do not necessarily have all the characteristics to make them competitive at present. The identification of niche markets that will allow for initial small volume commercialization is the best way to keep companies afloat during the first few difficult years when incumbent technology performance over cost ratios make adoption of new, less competitive technologies harder. These niche markets are usually characterized by lower volumes and more specific requirements and do not necessarily match the interests of existing technologies that are focused on providing for larger existing markets. They give the opportunity to new companies to generate income that will support them during their humble beginnings, allowing for further research and development activities which will optimize performance and eventually lead to larger volumes and increased cost-effectiveness through economies of scale.

Overcoming difficulties of this type mean that DSSCs are forecasted by IDTechEx to gain a modest market share in the next decade, reaching just under $300 million by 2023. Assuming that performance optimization will continue over the next decade, the final performance over cost ratios will finally become competitive, and together with the ability to establish new markets due to new form factors and functionalities, will lead to faster growth rates and larger market penetration in existing segments and creation of new market opportunities.

For more information and for detailed breakdowns of penetration in a variety of sectors, please see www.IDTechEx.com/DSSC 

For more read Energy Harvesting and Storage for Electronic Devices 2012-2022 

Source:  http://www.energyharvestingjournal.com/articles/dye-sensitized-solar-cells-third-generation-photovoltaics-00004746.asp?sessionid=1

Advertisements
This entry was posted in Solar. Bookmark the permalink.