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Thus, for the purpose of tracking technology trends, solar thermal technologies are divided into direct solar thermal and indirect solar thermal.
As depicted below on an annual basis, granted patents in photovoltaic technology dropped sharply from 2002-2005 before flattening out and rising slightly, and jumping significantly in the most recent four quarters. The
number of granted U.S. patents on the thermal technology side of solar energy
increased slightly from 2002 to 2005 before slowly declining.
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As depicted below, quarterly indirect thermal patents outpaced direct thermal patents in all years tracked but one. Both the direct and the indirect thermal
technologies have declined in the past four to five years. Generally speaking, indirect solar technology
(e.g., the conversion of thermal energy into mechanical or electrical energy) has consistently seen more patents and thus
innovation than its direct counterpart.
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(click the image for a larger version) Heslin Rothenberg Farley & Mesiti P.C. © 2009 Heslin Rothenberg Farley & Mesiti P.C. [1] Energy
Information Administration, Solar Thermal Manufacturing Activities,
www.eia.doe.gov/cneaf/solar.renewables/page/solarreport/solar.html. [2] Charles
W. Forsberg et al., High-Temperature Liquid-Fluoride-Salt
Closed-Brayton-Cycle Solar Power Towers, 129 J. Solar Energy Engineering 141, 145 (2007). [3] The
Renewable Energy Website, How Do PV Solar Panels Work, Jan. 10 2009
http://www.reuk.co.uk/print.php?article=How-Do-PV-Solar-Panels-Work.htm. [4] Nathan
Furr & Travis Bradford, PV Innovation in North America, Greentech
Media Inc. & the Prometheus Institute (Nov. 2008). [5] Id. at
13. [6] Id. [7] Id. at
14. [8] Id. [9] Id. [10] Id.
As depicted below, solar technology patents have trended upwardly for the last four quarters and are beginning to regain ground lost since 2002, when tracking of the Clean Energy Patent Growth Index (CEPGI) began.
Solar patents in the last quarter tracked approached the level of wind patents, which have been in second place to fuel cell patents in the CEPGI since 2006. Further, solar patents are poised to overtake wind patents in the coming year as per the trends in the quarterly components of the CEPGI below:
The solar technology field includes a broad spectrum of technologies from small scale to utility scale and photovoltaic to solar thermal. A detailed analysis of the Solar technology portion of the CEPGI, and the technologies within it, provides a more precise depiction of solar patenting trends. The broadest categories in the solar energy field are photovoltaic technology and thermal solar technology. These categories may also be further divided into distinct subsets, which we have analyzed below.
SOLAR TECHNOLOGY
Solar “thermal energy” technology is defined
exactly as one would expect, i.e., it is a way of harnessing the radiation received from the Sun to provide heat where it may be useful. The Energy Information Administration (EIA), which produces official energy statistics for the U.S. government, classifies the collection of the sun’s radiation for thermal energy into three categories – low temperature (less than 110° F), medium temperature (less than 180° F), and high temperature (greater than 180° F).[1] Typically low temperature collectors can be used for heating swimming pools or low-grade water and space heating, and medium temperature collectors can be used for domestic hot-water heating, solar cooling, or even solar cooking. Both low and medium temperature collectors are typical examples of the “direct” use of the thermal energy to accomplish a desired task, and are often passive technologies – which involves little
or no moving or active parts, and instead a thermal mass material is often
utilized to store heat from the sun and release it as necessary.
High temperature collectors are more typically
used to create electricity by operating generators (e.g., steam turned
turbines). This is accomplished by
concentrating solar radiation through the use of parabolic dishes and/or
reflective mirrors to superheat water or often a type of molten salt. This is an “indirect” use of the sun’s radiation - as it first creates
electricity, which then is used to perform a task. Such use of solar radiation is defined herein
as a type of “indirect” thermal technology, which refers to the conversion of
thermal energy into mechanical energy (e.g., rotating a turbine), instead of
the direct use of solar radiation as discussed above. High temperature solar thermal is generally
the solar technology used for large-scale electricity generation as it has much
higher conversion efficiency than Photovoltaic technology (see below) (near
41%).[2]
Photovoltaic (PV) systems use solar radiation to
create electricity directly, and is performed through the use of semi-conductors. They are often referred to as solar cells,
and complete solar cell modules are described as solar panels. PV systems are generally used on a smaller
scale, such as rooftops of homes and businesses, and typically has an
efficiency of between 5 and 15%.[3] Concentrating PV systems are of course an exception to this generality.
PV technology can generally be classified into three generations.[4] These generations are utilized to track the
PV patents as further described below.
The first generation is based on crystalline semiconductors,
largely silicon wafers.[5] Improvements continue to be made in this area
though the widespread adoption of this technology has been constrained until
recently by price and availability of
raw silicon.[6] The second generation consists of thin
film technology.[7] Thin film is usually processed from amorphous
silicon, cadmium telluride, or copper indium gallium di-selenide (CIGS) and has
gained popularity because it requires less semiconductor material than the
first generation.[8] Though more economical to provide, second
generation PV (i.e., thin film) generally has a lower efficiency than that of
the first generation.[9] The third generation includes newer
more experimental technologies that are further from the market[10]
than the first and second generations.
Technologies such as dye-sensitized solar cells, quantum dots,
nano-modified materials, and organic cells fall into this category.
In addition to the three generations of PV technology, a further Solar PV subcategory is defined as PV enhancement which spans the photovoltaic generations and is directed at the technological improvement of the efficiency of PV cells. Examples include technologies such as multi-junction cells (mjc), concentrated PV (cpv), and anti-reflective coatings.
Enabling technologies is defined as the innovations that must necessarily come with improved PV, but don’t directly impact the working of the PV
cell. Such technologies include power
conversion technologies, heat sinks, protective layering, roofing and panel
connection components, bypass diodes, sun tracking devices, and other such
technologies.
PV applications refer to the use of PV technology in
an invention without actual innovation relative to PV. Common examples include technologies that use
PV as a power supply for its operation – such as a solar car, an electrolysis
process or a solar-pumped device.
Finally, solar hybrid systems
may use both solar thermal and photovoltaic technologies, or one of these solar
technologies combined with another type of generation process (wind, hydro,
etc.).
Although rare, there are certain instances in the
following analysis where a patent is classified and counted in more than one
category. For example, sun concentrators
are sometimes directed at both concentrated PV (under PV enhancement) and solar
thermal energy generation (under indirect solar thermal). In addition, hybrid systems by their very
definition involve technologies that can be put into one or more category. As such, the hybrid patents are
simultaneously placed in the multiple categories. Because the hybrids are properly tracked in
their corresponding categories, the hybrid systems category is not included as
a subset of the larger photovoltaic or thermal group, but stands alone.
Thermal vs. Photovoltaic
As the graph by quarters show, however, thermal
technology in general has been much less volatile than its photovoltaic
counterpart and accounts for a much smaller percentage of solar technology
innovation. In fact, the plot of the
entire solar technology field appears to closely follow the photovoltaic trends
without much pull from the thermal technology trends.
The Thermal Technologies
As depicted in the chart below, the
top 10 patent owners in the Solar Thermal area since 2002 is dominated by
Boeing (14), which has patents directed to indirect solar thermal technologies including aspects of generating electricity via the
heating of fluids and solar molten salt technologies. In second place Mario Rabinowitz ( a scientist and CEO of Armor Research) holds 8 patents with 7 directed to indirect
technologies. United Technologies comes
in third with 6 patents in the indirect area relating to the heating of fluids
via solar thermal to create electricity.
Of the 160 patents granted since 2002 in the solar thermal area, it is
interesting that the top three solar thermal patent owners account for only 28 (or 17 percent) of the patents with the
rest of solar thermal patent owners owning only 2 or less patents each.
As will also be evident, the top holders of U.S. solar thermal patents are all U.S. entities except for Norio Akamatsu, the holder of 2 patents.
The Three Generations of Photovoltaic
As depicted below, the newer technologies did not lead the increases in PV technology. Instead, the first generation PV technology, after steep decline for four years running, began just as steep a rise in 2006. In fact, the first generation PV technology is the only technology whose most recent numbers exceed its 2002 starting point – meaning that innovation in this area is almost single handedly responsible for the leveling off of the solar energy patenting decline. The first generation solar technology is widely considered to have the theoretical best efficiency. Moreover, more innovators have entered the field, and the cost of silicon has decreased (with some dramatic price drops as
of late). See Ben Bahavar, Perspectives
on Photovoltaics: As Technologies Develop, Costs Decrease While Efficiency
Increases, June 2008; see also Rick Hodgin, Cost of Solar-grade
Poly-silicon Ingots Decreasing Rapidly, Apr. 15, 2009.
The second generation, or thin film technologies, on the other hand has shown a fairly consistent decline through
almost the entire period of our tracking. However, the most recent quarters show that the decline may be leveling
off.
The third generation technology made substantial
gains through most of the tracked period and matched the quarterly record total
in the 3rd quarter of 2009.
All in all, more patents have been granted on second generation
technologies at 129 than the first (78) or third (86) during the tracking
period.
Additional PV Technology
As depicted below, PV Enhancement has maintained
a steady reduction in innovation over the past seven years. In contrast, both enabling
PV technology and the use of PV in applications have been on the rise as of
late.
As shown in the chart below, Canon is far and
away the leader in Solar PV patents with over 2.5 times the number of patents held by Sharp, its closest
competitor. Canon has patents in almost
all PV categories, led by enabling (60), second generation (19), and first
generation (9) technology patents. Sharp
spreads its patents out among various subcategories including enabling (15),
first (4), second (8), third (5) and enhancement (5). Kanegafuchi (13), Boeing (9), and Sanyo (10)
also include large numbers of patents in enabling technologies. Mario Rabinowitz has concentrated his efforts
in solar enhancement technologies with 13 of such patents. Sunpower has concentrated on first
generation PV technologies with 10 patents in this area. Emcore has 4 patents in PV enhancement and 5
in enabling technologies. Konarka has
all its patents in third generation technologies. TDK has most of its patents in second
generation and enabling technologies. BP
has a predominance of its patents in second generation technologies while GE
has a majority in third generation PV patents.
Honda has several patents in first and second generation
technologies.
Of the top 15 PV patent holders, 7
are based in Japan while the rest are based in the U.S. However, as is evident from the chart, Japanese patent holders dominate the top 15 in absolute numbers of patents. In fact, the top three patent
holders, all from Japan, hold over 17 percent of all PV patents.
Hybrid Systems
As depicted below, patents in hybrid
technologies have hovered in very low numbers during the tracking period.
Please contact us at [email protected] if you have any questions or would like us to email you when we have updated this page or the CEPGI. CLEAN ENERGY PATENT GROWTH INDEX.COM
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