Photovoltaic (PV) Industry Primer
Overview of PV manufacturers, technologies, supply
chains, performance standards & certifications
Prepared for the
Green Electronics Council
Phase I
Final Report
April 13, 2015
Prepared by
Dustin Mulvaney, Ph.D.
Assistant Professor, Department of Environmental Studies
San Jose State University
I. Photovoltaic technologies
Photovoltaic (PV) modules are a particular kind of solar electric power technology that
harnesses photons, packets of light energy emitted from fusion reactions in the sun, and turns
them into electricity. PV modules generate electric current by the photovoltaic effect where
incoming photons push electrons across a voltage. While there are numerous other
technologies that are colloquially called solar power technologies, all non-PV solar technologies
utilize the thermal energy from the sun to heat liquids to produce hot water or to generate
steam. PV modules utilize photons to generate direct current and do not require moving parts
or steam like these other solar power technologies. The U.S. National Renewable Energy
Laboratory uses the following definition:
“Photovoltaic Module - a unit comprised of several photovoltaic cells that is the principal unit
of photovoltaic array. A photovoltaic module's size is on the order of 1 m2, although its size is
governed by convenience and application.”1
Electricity from photovoltaics
In the 1800s scientists first learned of a photoelectric effect. The first discovery is attributed to
Edmund Becquerel who learned some materials ejected electrons when exposed to light. The
principles of the photoelectric effect inform the functioning of PV modules, which utilize the
photovoltaic effect, a term used to describe electrons drawn across a voltage (e.g., when the
ejected electrons are carried off as electric current). Albert Einstein won a Nobel Prize for his
description of the mechanisms behind the photoelectric effect.
The photovoltaic effect is caused when a semiconductor layer with extra electrons absorbs an
incoming photon. This incoming photon raises the energy of the electrons in the atoms
absorbing the photon and elevates the electron energy from the valance band to the conduction
band. With electrons freely available in the conduction band, a circuit draws the free electrons
towards an electricity load or across the voltage. Conductive metal contacts harvest and carry
electric current through the PV module to a junction box interconnected to an electrical system.
Making semiconductors into photovoltaic cells
The basic architecture that turns semiconductors into PV cells is a design called the pn-junction,
as shown in Figure 1; “pn” means positive-negative, which is the interface between two
oppositely charged semiconductor materials. The pn-junction is the site where a semiconductor
with a positive charge is interfaced with one charged negatively. The p-Type semiconductor
layer conventionally represents the positive side of a solar cell and is depleted of electrons; it
has electron-holes where electrons should be. The n-Type semiconductor layer has extra
electrons.
The pn-junction is needed to “push” the change imbalance and allow electrons to flow from one
place to another. When the circuit is complete, this design (presence of electron-hole pairs) will
draw electrons out of the n-Type and toward the p-Type layer (and vice versa, holes flow
toward spaces formerly occupied by extra electrons). The positive charge can be an intrinsic
property of the material or can be achieved by chemically “doping” the semiconductor with a
material missing electrons. This charge can also be an intrinsic property of the material or
extrinsically doped.
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Figure 1. The pn-junction is the interface between the n-Type semiconductor and the p-Type
semiconductor.
Making PV cells into PV modules
PV modules are the devices that collect electricity from PV cells. Separate PV cells can be
crystalline wafers linked together by conductive wire. In thin-film PV modules, cells can be
deposited or etched into surfaces. Individual PV modules are eventually wired together in PV
arrays, sometimes called solar systems or PV power plants. Only rarely is a single PV module
installed by itself; when they are, it is usually for some remote application or very light power
requirements. Rooftop or distributed applications have installations on the order of ten to forty
PV modules. Utility-scale projects can be on the order of thousands to millions of PV modules.
PV cells are also integrated into some consumer electronics, but these are insignificant in terms
of overall volume.
There are several types of PV module installations for residential, commercial, and utility
projects. Grid-connected PV systems are tied into the electric power grid. These can range in
size from rooftop systems tied into the electricity distribution grid to utility-scale PV power
plants where arrays are tied into the high-voltage electricity transmission system. Off-grid
applications are PV modules used to power a home, research station, drilling rigs, etc. Some PV
systems may be integrated with other kinds of power systems such as biomass, small-scale
hydro, or diesel generators.
Major PV Technologies
Crystalline silicon PV
Crystalline silicon photovoltaic modules are the most common and widespread PV
technologies, with greater than 90% of the global market share. Types of crystalline silicon
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photovoltaic modules include mono-crystalline silicon PV modules and multi-crystalline
silicon PV modules. Mono-crystalline silicon semiconductor feedstocks are cooled into one
single crystal, while multi-crystalline silicon is cast into crucibles and is cooled into a composite
of many crystals. Many manufacturers offer both mono- and multi-crystalline modules. Monocrystalline silicon PV modules are usually more efficient, and they are usually the premium PV
modules on the market. Multi-crystalline silicon PV modules have a lower manufacturing cost
and usually have lower, but sufficient, photon conversion efficiencies. Some manufacturers
refer to multi-crystalline PV modules as poly-crystalline, which is not to be confused with
polysilicon, the primary feedstock for all crystalline silicon PV modules.
The semiconductor supply chain for a crystalline silicon PV module starts with quartz. Quartz
is mined and manufactured into metallurgical grade silicon, much of which is sent to steel
foundries. Metallurgical grade silicon is the silicon feedstock used to manufacture polysilicon,
the input that eventually is purified and shaped into silicon wafers that are used in crystalline
silicon PV modules.
Polysilicon is made from processing metallurgical grade silicon into chlorosilanes with
hydrochloric acid. Polysilicon production is done in places zoned for industrial chemical
facilities whereas other downstream phases of PV manufacturing can occur in light industrial or
commercial zones. The chlorosilanes are processed in a reactor where pure polysilicon is
deposited on crystalline rods. The rods are eventually removed and broken into polysilicon
chuck, the silicon feedstock sent for preparation into silicon wafers.
Making crystalline silicon wafers begins with melting polysilicon chunk. Mono-crystalline
silicon is formed by the Czochralski method where the higher temperatures and slower cooling
rates results in extremely pure crystalline silicon ingots. Multi- or poly-crystalline silicon is
made by melting polysilicon in crucibles where the cooling method results in multi-directional
crystals in the silicon ingots. The ingots are usually doped to give them an intrinsic charge (this
can either be p-type or n-type). Beyond the steps where polysilicon is melted into either monoor multi-crystalline silicon, all steps are the same for PV manufacturing.
The ingots are next sliced into bricks of silicon and then into individual wafers using wire saws
submerged in a slurry mixture. The wafers are next etched and cleaned to remove sawing
damage. Since the ingot preparation stage usually adds one charge, cells typically require
chemical doping on one side of the cell surface so each cell has one p-Type and one n-Type side.
This charge is achieved by diffusing chemicals into the top several millimeters of the PV cell.
An anti-reflective coating is added next with a mixture of ammonia and silicon nitride to
maximize the absorption of incoming photons. Finally the cells are fused together with metal
contacts so the cells are able to collect electrons for electricity. The cells are finally sorted and
checked for quality control.
PV cells are finally assembled into a PV module. In this stage the solar cells are laid out on a
backsheet and interconnected. Solar grade glass, which constitutes the bulk of the module’s
mass, is added atop of the cells and backsheet. The glass is finally covered and protected with
an encapsulant. A junction box is added to the box allowing for electricity interconnections to be
made. If the PV module design calls for a frame, this is added last.
Thin-film PV
Thin-film photovoltaic modules are an alternative module design based on thin-films of
semiconductor materials applied to a substrate like glass or plastic. They have the advantages
of fewer materials, lower manufacturing costs, less manufacturing energy costs, and faster
manufacturing times. While it is widely believed that thin-films are a theoretically lower cost
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PV module, many thin-film manufacturers have not been able to complete with crystalline
silicon on a price-basis. The most common thin-film PV technologies are cadmium telluride
(CdTe), copper indium gallium diselenide (CIGS) and amorphous silicon (a-Si). Figure 2 depicts
the cell architecture of these two technologies.
Figure 2. Basic PV cell design of the two most common thin-film PV technologies: CdTe and
CIGS.2
Most stages of cadmium telluride (CdTe) PV modules manufacturing take place in one facility.
Upstream semiconductor feedstocks are acquired from smelters and prepared by special
facilities that handle and prepare semiconductor metals. PV manufacturers typically purchase
powders of the semiconductor materials and use several techniques to evaporate or sputter
these powders to a substrate. CdTe PV modules use CdTe for one layer and cadmium sulfide
(CdS) for the other layer in the pn-junction. CdTe PV modules also require a transparent
conductive layer, which is used to harvest the electrons. Once all the layers are stacked, glass
and encapsulant is added, and frames are added where they are part of the design. A junction
box is usually the last item added before shipping off to customers.
Copper indium gallium diselenide (CIGS) PV manufacturing techniques are similar to other
thin-films. The CIGS layer is one layer and usually a CdS layer or Zinc sulfide (ZnS) layer
completes the pn-junction. CIGS PV modules have higher theoretical efficiencies than CdTe PV
modules and were the target of extensive venture capital investments from 2005 to 2011.
Amorphous silicon (a-Si) PV modules and cells have been available since the 1970s. They are
manufactured by depositing silane, a gas obtained from metallurgical silicon, onto a substrate
(silane is to silicon as methane is to carbon). These kinds of solar cells suffer from very low
conversion efficiencies and there do not appear to be many a-Si technologies competing with
mainstream PV modules. Some manufacturers apply an amorphous silicon layer on top of
crystalline silicon PV modules. Some have integrated germanium into the amorphous silicon
alloy to improve efficiencies. A few manufacturers have introduced micro-crystalline PV
modules, which are very thin-films of crystalline silicon.
Other more obscure PV modules are not made in appreciable volumes. Multi-junction PV
modules are stacks of several solar cells (stacks of several pn-junctions) designed to absorb a
broader range of the solar spectrum. They are very expensive to manufacture so limited to
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space, military, and telecom operations. Some multi-junction PV modules utilize a large glass
or plastic Fresnel lens to focus a wide area onto a much smaller PV cell surface. These are very
expensive and are typically destined for telecom, space, and military applications. The most
widespread semiconductor materials for multi-junction solar cells are gallium arsenide, indium
gallium phosphide, germanium, and indium phosphide. Dye-sensitized and organic PV cells
remain in laboratories and at pilot-scale manufacturing.
II. Photovoltaic manufacturers
The photovoltaic (PV) industry has experienced tremendous growth over the past decade.
Global production was nearly 40 Gigawatts (GW) in 2013, and the cumulative amount of PV
modules ever sold passed 140 GW in early 2014.3 U.S. PV installations in 2014 were 6.2 GW.4
Figure 3 below from by the European Photovoltaics Industry Association depicts the
tremendous growth in PV installations by regions.5 Cumulative PV module installations tripled
from 2009 to 2011 and doubled again from 2011 to 2013.
Figure 3. Cumulative PV installations from 2000 through 2013, graphic courtesy of EPIA.
The PV industry measures the volume of photovoltaic modules shipped by the total nameplate
capacity of modules sold. The nameplate capacity is the peak power output as measured in DC
electrical current (i.e., before an inverter converts DC electricity to AC). While there is no
standard for power output, a typical PV module is generally capable of delivering 200 to 300
Watts of power.6 The nameplate power output is also used to describe the capacity of a
manufacturing facility. A 1-GW manufacturing facility can produce 1 GW worth of PV
modules in a year. It is also used to describe the size of a power plant (e.g., 1 GW, 25 MW, etc.)
or rooftop system (e.g., 4 kW).
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A PV manufacturer is a company that produces a brand-name PV module capable of generating
electricity with the photovoltaic effect. Some manufacturers outsource a portion of their
production to an OEM or contract manufacturer but sell it as their own brand name. In these
cases, the brand name is described as the manufacturer because they are the company that
delivers the product to the next stage in the PV module supply chain, which might be directly to
a consumer, to an installer, project developer, or wholesaler.
Figure 4. Market share of PV module shipments in 2013
PV manufacturers do not all make their annual production totals available, so the data in
Figures 4 and 5, which show relevant market share are based on the industry total production
reported by EPIA and information collected individually from different manufactures and
financial analysts.
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Figure 5. PV manufacturers, 2013 market share, headquarters, and manufacturing locations
The PV industry is led by a handful of very large module manufacturing companies. Twenty or
so companies make up about 75% of the PV module market. Not all companies report their
production volumes, so the output of the entire industry is not known precisely. The remaining
companies are small-scale or contractor/made-to-order facilities or may be in pilot production.
Some companies are “pure-play” companies, meaning they specialize in manufacturing PV
modules but not anything else beyond auxiliary equipment for PV systems. Several PV
manufacturers are large multinational electronics companies: Kyocera, Sharp, Panasonic, and
LG, for example. Other companies are owned by larger companies such as SunPower who is
owned by multinational oil major Total. First Solar is one of the most well capitalized PV
manufacturers.
There are very strong tensions among PV module manufacturers and some of the key input
suppliers because of ongoing trade conflicts between nations. Several U.S. PV manufacturers
filed suit with the Department of Commerce against China on counter-veiling duties and anti-
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dumping allegations. Commerce has found in the favor of U.S. manufacturers and a tariff has
been leveled against Chinese imports equal to the estimate of the value of the subsidies.
Manufacturers in the EU filed a similar suit, and similar tariffs are expected. In response, China
filed its own complaint against U.S. manufacturers of polysilicon, a key input for crystalline
silicon PV modules alleging U.S. subsidies led to polysilicon dumping in Chinese markets.
Listed below are attributes and highlights from the top twenty manufacturers for which there is
good production data available. Data was collected from various sources including industry
association information such as is available from the Solar Energy Industries Association (SEIA)
and the European Photovoltaics Industry Association (EPIA), as well as from financial analysts,
company websites and quarterly financial reports.
Individual PV manufacturers
The key differences between the types of PV modules made by manufacturers are the kind of
semiconductors, size, and efficiencies. The key attributes include the PV module efficiency,
which is a measure of the amount of photons that can be converted into electricity. PV modules
also come in various sizes and dimensions, so buyers might decide to purchase a PV module
brand because of the size of available offerings. Another important consideration for some
buyers is the length of warrantee. Below are descriptions of the major PV module
manufacturers.
Yingli Solar is a vertically integrated manufacturer of crystalline silicon PV modules from
polysilicon to module. Yingli is a popular brand name due in part to high spending on
advertising such as FIFA football endorsements and several other mainstream public sporting
events. Yingli’s manufacturing base is spread across the cities of Baoding, Haikou, Tianjin, and
Hengshui in China where they produce all the stages from polysilicon to PV module. Yingli was
about 8.4% of global market share in 2013. They currently manufacture three models of
multicrystalline PV (poly-crystalline) modules and one mono-crystalline PV module.
Trina Solar is a Chinese PV manufacturer of multi-crystalline PV modules, producing every
stage from polysilicon to PV module (though they also purchase polysilicon from other
producers). Trina had the top score in SVTC Solar Scorecard in 2013 and 2014. Trina was
roughly 6.7% of global market share in 2013. They currently offer four models of PV module
that vary in size and power output. They recently announced expansion of production into
India.
Canadian Solar is competing to be the largest PV manufacturer by volume in 2015. Their global
headquarters is in Guelph, Ontario. They operate seven production facilities in China.
Canadian Solar was roughly 5% of market share in 2013. They currently offer four polycrystalline and three mono-crystalline PV modules.
Sharp manufactures multi-crystalline PV modules in Japan from ingot to module. They also
make a unique stacked micro-crystalline silicon and amorphous silicon thin-film PV module.
They recently closed a long-running manufacturing facility in Tennessee (USA). Sharp
accounted for roughly 5% of global market share in 2013; they were the largest manufacturer
throughout the 1990s and 2000s. They offer eight different models of multi-crystalline PV
modules.
Jinko Solar is a vertically integrated manufacturer of poly-crystalline PV modules from ingot to
module. Jinko occupied 4.6% of global market share in 2013 with production in facilities in
Shangrao (Jiangxi) and Haining (Zhejiang), China. They offer approximately 12 module types
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including several models that have built in inverters, so-called smart PV modules. Jinko Solar
was a latecomer to the top ten manufacturers.
First Solar makes thin-film cadmium telluride (CdTe) PV modules in Perrysburg, Ohio and
Kulim, Malaysia (a German factory has closed operations). Most of their customers are owners
of utility scale power plants such as NRG and Warren Buffet’s Mid-American. Recently, they
contracted directly with Apple Computer to build a large-scale PV farm to offset Apple’s U.S.
electricity use.7 Some of these power plants are quite extensive, up to twenty-five square miles.
First Solar recently announced they would be pursuing homeowner markets, but they also
continue to fill their pipeline with very large-scale utility PV power plants. First Solar shared
roughly 4.8% of global market share in 2013, down from 12% of market share in 2009.
ReneSola shared roughly 4.5% of global PV module market share in 2013 with nearly 2 GW of
vertically integrated production capacity in China. They offer 46 types of mono-crystalline PV
modules and 82 multi-crystalline modules. They also sell wafers and cells to other
manufacturers.
JA Solar is a manufacturer with 3.5 GW of mono- and poly-crystalline silicon wafer, cell, and
module manufacturing capacity spread across China in the cities of Shanghai, Fengxian,
Ningjin, Yangzhou, Fengxian, Donghai, and Hefei. JA Solar recently announced they would
partner with an unnamed original equipment manufacturer (OEM) for cell manufacturing. In
2013 they had 3.2% market share of global PV module shipments. JA Solar offers 23 different
models of PV modules. They also sell six types of mono- and poly-crystalline silicon solar cells.
Kyocera is a Korean manufacturer of mono- and poly-crystalline PV modules with
manufacturing operations in Japan (Shiga, Mie Prefectures), the Czech Republic, China
(Tianjin), and Mexico (maquiladoras). They offer six module models in their fleet that range in
power output. In 2013, they had 3.2% market share.
SunPower is a vertically integrated manufacturer of mono-crystalline silicon PV modules
headquartered in San Jose, California with operations in the Philippines. SunPower had
roughly 3% of market share in 2013. It is unclear how many PV module models are available,
but at least one high-quality mono-crystalline module is offered.
SolarWorld is a manufacturer of mono-crystalline PV modules with operations in the USA
(Oregon), Germany, and South Korea. SolarWorld held roughly 3% of market share in 2013.
They offer twelve different models of mono-crystalline PV module.
REC Solar is a vertically integrated multi-crystalline silicon PV manufacturer making
everything from polysilicon to PV module with manufacturing in the USA and Philippines.
REC is roughly 2% of global market share in 2013. They currently offer four models of multicrystalline PV modules.
Motech is a vertically integrated multi- and mono-crystalline silicon PV manufacturer with
operations in Tainan, Taiwan. They are a company that benefited from the U.S.- China trade
dispute because modules were not subject to the import tariff. They currently offer three
modules of multi-and mono-crystalline types and constitute about 0.4% of the PV module
market. Motech also sells PV cells.
Hanwha Q-Cells is a vertically integrated producer of mono- and multi-crystalline PV modules
with production facilities in Qidong, Jiangsu Province, China, Malaysia, and Germany. The
company is a combination of Q-Cells and Hanwha SolarOne (formerly SolarFun). Q-Cells was
a German solar cell company that was the top PV cell manufacturer in 2009 before of long bout
of economic troubles (largely induced by the rise of Chinese PV manufacturing) led to its
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acquisition by the emerging Chinese manufacturer. Hanwha Q-Cells shared roughly 2.2% of
global market share in 2013. As of 2015, their manufacturing capacity was 3.3 GW. Hanwha QCells purchases polysilicon from Hanwha Chemical.
The Mitsubishi Electric Corporation manufacturers mono-crystalline silicon PV cells and
modules, representing about 1.3% of global market share in 2013. They have been
manufacturing PV modules since 1974 in Japan (Nagoya; Osaka, Nagano Prefectures). Its
parent company Mitsubishi is among the largest corporations in the world. They currently offer
one mono-crystalline PV module model, but appear to have recently offered both mono- and
poly-crystalline PV modules.
Panasonic manufactures about 1.3% of the global PV market in Japan. Many of their customers
are more familiar with the brand name Sanyo, which appears to have been replaced with the
name Panasonic since the two companies merged. They offer poly-crystalline PV modules and
an advanced mono-crystalline PV module with a second layer of amorphous silicon solar cells.
LG Solar (headquarters Seoul, South Korea) produces mono-crystalline PV modules in Gumi,
South Korea. They currently offer three mono-crystalline PV module models. They occupy less
than 2% of the global market for PV modules.
Solar Frontier makes CIGS thin-film PV modules in Miyazaki, Kunitomi, and Tohoku, Japan. It
is only one of two major thin-film players in the PV industry. It comprised nearly 3% of market
share with operations in Japan. The company was formerly Showa Shell. They offer one CIGS
thin-film PV module model.
Suntech is a vertically integrated manufacturer of cells and PV modules with manufacturing in
China. Suntech recently emerged out of bankruptcy after being the largest manufacturer in the
world in 2011. In 2013, they represented 2% of the global market share. They offer two multicrystalline module types and four mono-crystalline PV module lines.
Thin-film manufacturers tend to be smaller in scale and less mature along product
development. Many remain in the pilot phase. A few notable thin-film manufacturers include
Hanergy, which produces thin film photovoltaic and is owned by a $36 billion company
controlled by Li Hejun, one of the richest men in China. Calxyo made CdTe PV modules and
was spun-out of Q-Cells in 2009 and continues to operate at a small scale.
There are numerous smaller PV manufacturing companies on the order of 100s. There are
several notable contract manufacturers including Flextronics, FoxConn, and Jetion. Flextronics,
until recently, made PV modules for SunPower in Milpitas, California. Jetion is a contract
manufacturer that also has its own brand name. Its production facilities are in the Jiangsu
Province in China. FoxConn is exploring expansion into more contract manufacturing for PV
modules, including an agreement with SunEdison for a facility in Mexico.
III. Photovoltaic supply chains
Understanding PV module supply chains is complicated by the fact that companies have
different levels of vertical integration. Some PV manufacturers produce all stages from
polysilicon to PV module, while for other manufacturers, polysilicon could be three tiers
removed from modules assembly. Non-silicon and non-semiconductor supply chains are
similar across PV manufacturers. Figure 6 illustrates the crystalline silicon PV module supply
chain.
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Figure 6. Components of a crystalline silicon PV module
Polysilicon
Polysilicon is the feedstock that solar wafer manufacturers start with when melting to solar
grade crystalline silicon. Globally polysilicon manufacturing takes place in several locations
across the U.S., China, Germany, South Korea, Japan, Malaysia, the Philippines, and India. The
following eight companies account for roughly 80% of polysilicon production:
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Hemlock Semiconductor (USA, joint venture of Dow Corning, Shin-Etsu, Mitsubishi)
Wacker-Chemie AG (Germany)
Renewable Energy Corporation (REC)(Norway, Washington)
Tokuyama Corporation (Japan)
MEMC Electronic Materials (USA; manufacturing in Korea, Taiwan, Malaysia, Italy,
Japan, Texas, Missouri)
Mitsubishi (Japan & USA)
Sumitomo-Titanium (Japan)
GCL-Poly (China)
In addition, several PV manufacturers make some of their own polysilicon including Yingli and
SolarWorld. First tier suppliers to polysilicon manufacturers are suppliers of metallurgical
silicon, and second tier suppliers are semiconductor grade quartz mining operation (several
wholesalers could be intermediaries between these purchases). Companies who buy polysilicon
may sell wafers or carry out all of the subsequent steps of wafer, cell, and module
manufacturing and assembly.
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Thin-film semiconductor feedstocks
Figure 7 illustrates the building blocks for thin-film PV modules. Thin-film PV manufacturers
rely on specialty refineries that produce high quality semiconductor powders of the metals they
use in manufacturing. CdTe PV manufacturers require supplies of CdS and CdTe. Many thinfilm PV technologies include indium. 5PLUS is a major supplier of both cadmium-based and
indium-based semiconductor feedstocks. Major suppliers of indium include Tosoh (Japan),
Indium Corporation (USA), and American Elements (USA). Thin-film material feedstocks for
CIGS include gallium, which is derived from bauxite.
Figure 7. Thin-film PV components
Specialty chemicals
Specialty chemicals companies comprise the suppliers of materials needed for cell preparation,
manufacturing, and reactor cleaning among other plant operations. This includes dopants, antireflective coatings, solvents, metallization pastes, etc. Here PV manufacturers could be buying
from any number of Fortune 500 specialty chemical manufacturers. Dupont (USA), Dow (USA),
Linde (Germany), BASF (Germany) are among the major specialty chemical providers to the PV
industry.
Silver and aluminum metallization pastes are also a key input provided by specialty chemical
manufacturers Dow (USA), Dupont (USA), Giga Solar Materials (Taiwan), Guangzhou Ruxing
(China), and Heraeus Materials Technology (Germany). These pastes can contain lead and
silver and are used in crystalline silicon PV modules.
Dopants are used to give the charge to semiconductor materials and are supplied by Linde
(Germany), Techneglas (Ohio, USA), and Air Liquide (France). Doping gases are critical inputs
in crystalline silicon PV manufacturing. They may be also used in some kinds of thin-film PV
manufacturing, though less likely.
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Solder and ribbon are key pieces needed to interconnect a PV module. Major providers of these
inputs include Dow (USA), Dupont (USA), Giga Solar Materials (Taiwan), Guangzhou Ruxing
(China), Hitachi Metals (USA), KME (Italy), and Alpha (USA).
Bulk chemicals
Bulk chemicals are chemicals that are sold to multiple industries and are not specific to PV
manufacturing.
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Hydrochloric acid is a major input to the manufacture of crystalline silicon PV modules.
Major suppliers include Sumitomo (Japan), Tokuyama (Japan), Hubbard-Hall (USA),
Shandong Bangde Chemical Co. (China)
Major suppliers of hydrofluoric acid include Linde (Germany), Hubbard-Hall (USA),
Shandong Bangde Chemical Co. (China)
Suppliers of sulfuric acid include Chihong Zn & Ge (China), Hubbard-Hall (USA),
Shandong Bangde Chemical Co. (China)
BASF (Germany), Hubbard-Hall (USA) are major suppliers of nitric acid; Shandong
Bangde Chemical Co. (China)
Hydrogen peroxide is supplied by Hubbard-Hall (USA); Shandong Bangde Chemical
Co. (China)
Phosphoric acid is made by Hubbard-Hall (USA), Shandong Bangde Chemical Co.
(China)
Potassium hydroxide is produced by Hubbard-Hall (USA), Shandong Bangde Chemical
Co. (China)
Sodium hydroxide suppliers include Gajanan Enterprises
Bulk gases
Nitrogen trifluoride is a potent greenhouse gas used to clean reactors. Major suppliers include
Linde (Germany). Ammonia is used in high quantities in PV manufacturing. Suppliers include
Air Products (SA), Linde (Germany), and Sumimoto (Japan). Silane is used by both thin-film
and is supplied by Linde (Germany), REC Silicon (USA), and Air Liquide Electronics (France).
Backsheet
The backsheet is a polymer material that protects PV cells. Backsheet suppliers include several
large multinational chemical companies that specialize in advanced polymers such as Dow
(USA) and Dupont (USA).
Solar glass
Solar grade flat glass providers to PV industry are flat glass manufacturers a subset of the global
glass market. High quality solar grade glass is needed for PV modules. This glass is lower in
impurities such as iron. Solar glass is about 1% of the global flat glass market. The largest
suppliers of solar glass are AGC Solar (Belgium), Pilkington (UK), Saint Gobain Solar
(Germany), Shanghai Flat Glass Co. (China), and Guardian (USA).
Thin-film substrates
Some thin-film semiconductor layers are applied to substrates other than glass. Dupont for
example makes a polymer Kapton® that is used to apply CIGS thin films.
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Encapsulant
Encapsulant is a polymer material affixed/cured atop the glass on a PV module to protect it
from moisture. Significant providers of this input include 3M (USA), Bridgestone (Japan),
Tosoh (Japan), Hangzhou First PV Material (China), Jiangsu Sveck New Material (China), and
STR (USA).
Junction box
The junction box is the interconnection interface between the electricity generated by the
modules and the electricity system the power is being delivered to. It is usually on the back on
the module. In most applications the junction box is connected to an invertor, which is then
routed to the electrical box in a home. Major manufacturers of junction boxes include GZX PV
Technology (China), Hengda Electrical (China), Renehesolar (China), Sunter & NBZH (China)
Tyco Electronics (USA).
Frames
Frames of aluminum are generically provided from aluminum suppliers. Many kinds of PV
modules do not use frames.
IV. Existing certification standards
There are numerous certifications that PV companies list on their websites and the label of PV
modules. These are largely related to quality management and safety specifications for
electronic products. The most common safety, electrical, and environmental standards used in
the PV industry are listed below.
Underwriters Laboratory (UL) (USA & Canada) provides several safety and performance
standards and tests for PV modules. UL 1703 is the basic safety standard UL has used for PV
modules since the 1980s and assess fire, electrical, and mechanical hazards.8 It is the basis for
the International Performance Standard (IEC) 61730. Other organizations provide the IEC
Standards certification including TüV Rheinland. IEC 61000 is a power quality standard
certification. IEC 61215 describes the design qualifications and type approval for terrestrial
outdoor PV cells and modules. There are a number of other IEC specifications that relate to
power electronics, environmental testing, and accelerated weathering/aging.
There are numerous certifications that attempt to forecast the durability of PV modules in
particularly harsh climates. PV modules can be certified for having undergone Ammonia
Corrosion Testing and Salt Mist Corrosion Testing. TüV Rheinland, UL, and others have
developed similar standards. These are not necessarily put on the labels of PV modules.
TruSolar® is a standard and accreditation body developed for uniform credit screening for PV
9
modules and power plant projects. The tool is meant to aid the investment community by
providing a financial risk scoring system for PV investments by providing an independent risk
assessment methodology. The workgroup of TruSolar includes numerous companies from
across the PV module value chain from various sectors including ABB, ABM, Assurant, Booz
Allen Hamilton, Distributed Sun, DuPont PV Solutions, Mosaic, PanelClaw, the Rocky
Mountain Institute, SMA America, Standard & Poor’s, UL (Underwriters Laboratories), and
U.S. National Labs such as the National Renewable Energy Lab (NREL) and Sandia National
Labs.
The Solar Quality Initiative is a “best practices effort” with the goal of assuring quality in the
growing residential PV module market.10 The effort was spearheaded among several
15
organizations, companies and institutions including Sungevity, NREL, and NRG Energy. It is
not clear if the initiative has enough inertia to be more visible.
The International Standards Organization (ISO) offers guidelines that are the basis for
certifications including the ISO 9001-2000 Quality Management System and the ISO 14001
Environmental Management System, though they are not PV industry specific. ISO 14001
covers numerous environmental themes related to environmental risks form developing and
producing PV modules. Many PV manufacturers report having factories undergo ISO 14001
certifications.
A Restriction on Hazardous Substances (RoHS) certification demonstrates that PV
manufacturers’ modules are below acceptable levels of lead or cadmium in their modules. A
handful of companies list RoHS compliance certifications on their website.
OHSAS 18001 is a British Standard used internationally as a health and safety standard for
workers. Several PV manufacturers have certified factories in developing countries to OHSAS
18001.
PV Cycle is a recycling scheme in Europe that collects end-of-life PV modules. PV modules
sold with the PV Cycle logo mean that the manufacturer in a member of the collection scheme
established in Europe.
SA8000 is an international standardized code of conduct for improving working conditions
based on the UN Universal Declaration of Human Rights, Convention on the Rights of the
Child, and the International Labor Organization.
Global Reporting Initiative (GRI) is a reporting framework for disclosure of sustainability
performance and governance. The guidelines offer a framework of metrics and social criteria
for full disclosure of social and environmental performance.
The Carbon Disclosure Project is an effort to get companies to annually disclose (and
ultimately reduce) overall emissions due to operations.
Carbonfree Certification is a certification established by the carbon fund.
Cradle to Cradle is the certification scheme based on the concept popularized by Bill
McDonough. It rewards manufacturers for developing processes than minimize waste.
SunPower is the only PV manufacturer with this certification.
V. U.S. and global purchasing system
The leading global markets for PV modules are Germany, Spain, U.S., China, Czech Republic,
Italy, France, and Japan. Germany maintains the global lead in PV installations. A generous
feed-in-tariff1 offered German consumers the opportunity to sell electricity to the electric utility
at a profit. Other major nations with large amounts of PV installations also used a feed-in-tariff
including Spain, France, Italy, the Czech Republic and Japan. Feed-in-tariffs are far more
1
A feed-in-tariff is electricity rate paid to owners of PV modules or other renewable energy devices that
are interconnected to the electricity grid. An owner of a PV system in this scheme is an independent
electricity generator able to sell renewable electricity back to the electric utility at a specified rate, usually
a generous one intended to spur investment in PV modules. In some schemes the rate is set at the
“avoided-cost” of electricity to the utility (the cost of acquiring the electricity if the PV modules were not
contributing to power supply.)
16
generous of an incentive to an electricity customer than the net metering scheme2 used in the
U.S. for grid-tied PV, which accounts for 99% of the residential PV module market. The major
driver of PV module adoption in the U.S. is a series of state-level renewable portfolio standards
that require investor owned utilities to acquire a certain portion of electricity from renewable
sources. The U.S. maintains a strong position in PV module adoption with leading states for
installations ─ California, North Carolina, and New Jersey.
Figure 8. Global purchasing system for PV modules
There are thousands of downstream purchasers of PV modules. The schematic in Figure 8
categories the major purchasers and end users of PV modules. Most PV modules in all markets
are sold to installers or project developers directly or through a series of wholesalers. Some of
the most popular names of residential installers include Sungevity, SolarCity, SunRun, Verenga
Solar, OneRoof Energy, Vivint Solar, American Renewable Energy, Astrum Solar, Solar Design
Tech, Namaste Solar, Roof Diagnostics Solar, Solar Topps, Solar Energy World, and hundred of
others. Commercial solar installers include Solar City, REC Solar, Meridian Solar, Tecta Solar,
Trinity Solar, Sunetric, and Innovative Concepts. Top utility scale installers include First Solar,
E Light Wind and Solar, Swinerton Renewable Energy, Strata Solar, and Quanta Power
Generation.11
Some PV manufacturers sell their brand-name PV modules to subsidiary companies that
exclusively install these modules. For example, the PV manufacturers SunPower and REC own
subsidiary companies that specialize in the installation of PV modules for the residential and
commercial markets. Other PV module installation companies have exclusive agreements with
one or a few PV module brands. Other installers simply offer the cheapest PV modules
available, which can come from any number of sources including wholesalers.
2
Net metering is an electricity rate that allows a PV module owner to be credited by the utility for
electricity delivered to the grid. Net metering allows owners to “zero-out” their electricity bill if what
they deliver to the grid on balance equals what they consume from the grid. Net metering is not as
strong as an incentive as a feed-in-tariff, which entices PV modules owners to build arrays that can
deliver more electricity to the utility’s electricity grid than consume.
17
PV manufacturers also sell PV modules to power plant developers. These can be third party
firms who specialize in the construction and installation of solar power farms. They can also be
LLCs of the parent companies who work out power purchase agreements to sell the electricity
to electric utilities. Where LLCs of parent companies are used, power plant developers
eventually enter into a contract to sell the power plant to large merchant electricity wholesalers.
For example, First Solar manufacturers modules that are sold to a subsidiary LLC it owns, and
after the power plant is built they sell it to a larger merchant power generator like
MidAmerican, NRG, or Florida Power and Electric. SolarWorld, SunPower, and First Solar are
example of companies that have constructed such solar power plants. Numerous private
companies have also begun to seek out dedicated solar power farms to cancel out electricity
consumed at corporate campuses. Apple computer for example recently contracted to buy a
power plant to be built by First Solar.
Globally, more than half of PV systems are residential or commercial systems with more than 80
GW of the 140 GW of total capacity installed. The remaining 60 GW are utility-scale PV power
plants. The U.S. has a higher proportion of PV modules installed in PV power plants. In 2013,
the U.S. installed 60% of PV modules in utility-scale projects, 23%in non-residential systems,
and 17% in the residential sector.12 The EIA forecasts the largest growth segment in the U.S. is
the distributed/rooftop class.
U.S government agencies would not purchase PV modules directly from manufacturers unless
those companies are vertically intenerated from the module to installation phase. The is largely
an artifact of the tax equity schemes used to incentivize PV module purchases in the U.S.
Government would most likely enter into a power purchase agreement with a PV module
installer because government cannot take advantage of the 30% Investment Tax Credit. Given
the significance of the 30% tax break, most third parties can install and sell solar electricity to
government cheaper than government could do on its own. There may be some government
institutions that do purchase PV modules outright, but there is not readily available
information.
Specifications might be integrated into power purchase agreements between the utility and
solar developer, or a homeowner and an installer. Or, they might be specified as a requirement
for a financial incentive. The California Solar Initiative program that incentivized residential
and commercial solar from 2006 to 2013 set forth certification requirements for fire and electrical
safety as a precondition for the rebate. The Investment Tax Credit, valued at 30% of the total PV
array installation cost, could integrate specifications into the U.S. tax code.
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End Notes
NREL [National Renewable Energy Laboratory]. 2015. Glossary of Solar Radiation Resource Terms.
http://rredc.nrel.gov/solar/glossary/gloss_p.html
1
2
NREL [National Renewable Energy Laboratory]. PV Research. http://www.nrel.gov/pv/thinfilm.html
3
Energy Information Agency. 2014. Trends in Photovoltaic Applications.
Solar Energy Industries Association. 2015. U.S. Installs 6.2 GW of Solar PV in 2014, Up 30% Over 2013.
http://www.seia.org/news/us-installs-62-gw-solar-pv-2014-30-over-2013
4
EPIA. 2014. Global Market Outlook for Photovoltaic 2014–2018.
http://www.epia.org/fileadmin/user_upload/Publications/EPIA_Global_Market_Outlook_for_Photovoltai
cs_2014-2018_-_Medium_Res.pdf
5
This translates to 3 to 5 PV modules per kilowatt (kW) installed, 3 to 5 thousand modules per megawatt
(MW), and 3 to 5 million modules per Gigawatt (GW).
6
http://www.greenbiz.com/article/apple-swings-fences-848-million-solar-powerdeal?mkt_tok=3RkMMJWWfF9wsRogs63IZKXonjHpfsX56%2BwlWKSylMI%2F0ER3fOvrPUfGjI4HS8JnI
%2BSLDwEYGJlv6SgFSLHEMa5qw7gMXRQ%3D
7
The scope for UL 1703 - Standard for Flat-Plate Photovoltaic Modules and Panels are as follows. (1.1)
These requirements cover flat-plate photovoltaic modules and panels intended for installation on or
integral with buildings, or to be freestanding (that is, not attached to buildings), in accordance with the
National Electrical Code, NFPA 70, and Model Building Codes. (1.2) These requirements cover modules
and panels intended for use in systems with a maximum system voltage of 1000 V or less. (1.3 These
requirements also cover components intended to provide electrical connection to and mounting facilities
for flat-plate photovoltaic modules and panels. (1.4) These requirements do not cover: (a) Equipment
intended to accept the electrical output from the array, such as power conditioning units (inverters) and
batteries; (b) Any tracking mechanism; (c) Cell assemblies intended to operate under concentrated
sunlight; (d) Optical concentrators; or (e) Combination photovoltaic-thermal modules or panels.
8
9
TruSolar. 2015. http://www.trusolarscore.com/
10
The Solar Quality Initiative. 2015. http://www.solarquality.org/
Solar Power World maintains a list of the top commercial, residential, and utility-scale installers. See
http://www.solarpowerworldonline.com/top-250-solar-contractors/2013-top-100-residential-solarcontractors/
11
Solar Energy Industries Association. 2014. Solar Market Insight Report 2013 Year in Review.
http://www.seia.org/research-resources/solar-market-insight-report-2013-year-review
12
19