What does the solar energy patent landscape look like?

Patent systems exist to encourage innovation by providing a government-granted monopoly in return for public disclosure of new inventions. Thus, analysis of published patent data can provide a useful indicator of research and development activity in any field of technology, at least for those inventions considered to be commercially valuable and worth protecting. An analysis of solar energy inventions reveals some interesting trends.

Solar energy technology landscape
When the inventions are spread out on a map where similar technologies are clustered, it is possible to gain an appreciation of the focus and intensity of developments in each technical field. Figure 1 shows a technology landscape map produced by Watermark Information Services Group using the Thomson Innovation search and analysis tools provided by Thomson Reuters. This map is a useful way to visualise patenting activity in a sample collection of patented inventions.

For our research, we chose to focus on solar energy because the natural environment in Australia would seem to suggest that this form of alternative energy is particularly suited to the country. Government support is also focused in this area through the Solar Flagships programme.

Figure 1 shows a technology landscape map, the contours of which reflect 18,300 solar energy inventions (based on the International Patent Classification in combination with suitable keywords) located within the full coverage period (see www.thomsoninnovation.com/ti/contentsets/patents/) of the international Thomson Innovation database. Essentially, the higher the peak, the more patents lie in a particular technology field. The positioning of each peak is not important, other than to note that the closer together the peaks are located on the map, the closer the technologies are related. Conversely, the further apart the peaks, the further apart the technologies.

Figure 1: Australian originating inventions (red dots) in the international solar energy technology landscape 

There are essentially five main peaks appearing within the international technology landscape:

• Solar thermal technologies, including storage and heat transfer systems.
• Organic compounds and polymers, and solar cells using these technologies.
• Optical elements and devices, including modules and combinations with solar lighting.
• Power conversion equipment and power electronics.
• Semiconductor structures used in photovoltaic cells.

There are also lesser peaks around organic compounds and polymers within devices, photo electric conversion and dye-sensitised solar cells. Thin films, photovoltaic modules and assemblies, solar water heaters and optical/solar concentrators are further areas of patent activity.

Recent international trends
From Figure 1 it can be seen that solar thermal has, by a significant degree, been the most active area of development. However, it must be borne in mind that the period of time represented in this map is substantial, so our research team also investigated recent changes in patenting activity.

Looking specifically at inventions published in 2009, we found that most recent research and development has been in the field of photovoltaic solar cells, and more particularly organic solar cells. The table below shows the number of inventions published in each field.

Technology field	Number of publications
Photovoltaic	1294
Organic	983
Thin film	634
Solar thermal	473
Dye-sensitised	150

There would appear to be some overlap between the various photovoltaic technologies, but together photovoltaics quite clearly outrank solar thermal inventions many times over. In addition, it can be seen that research and development in organic solar cells is far more active than in thin-film or dye-sensitised technologies.

By time-slicing the data over the past decade, we found that the number of patent publications occurring in each of these technological fields has increased significantly, particularly since 2005/2006. Once again, the most rapid growth has been in organic solar cells.

Solar energy research and development in Australia
Our research team then proceeded to conduct an analysis of solar energy inventions originating in Australia. Since 1983 (the beginning of the database coverage period for Australia), there have been 159 Australian-originating solar energy patents. These are depicted as red dots on the technology map. It can be seen that the technology fields of the inventions are quite diverse, with perhaps a slight concentration around solar thermal, but otherwise a relatively even spread. In the last two years there has also been some concentration around semiconductor structures.

Interestingly, there has been only one Australian-originating patent publication relating to the field of organic solar cells, thus suggesting that Australian researchers have some catching up to do in this fast-developing technology. However, the Australian Patent Office records show quite a number of recently filed patent applications by entities involved an Australian organic solar cell consortium. Those applications do not yet appear on the technology landscape map because they are not yet published. It will be interesting to see how the patents and their underlying technology evolve over coming years.

Conclusion
An analysis of patent data can reveal some interesting facts and trends in research and development activity. In relation to solar energy technologies, a technology landscape map shows that the most active area of international research over the past few years has been in the field of organic solar cells. While this technology is still in its infancy, especially in Australia, it seems that the opportunities for technology developers and investors will be significant.