lightweight high-tower wind turbines. Its all-steel
120 m towers weigh only 226 tons, 30% lighter
than other all-steel or steel-concrete towers.
Goldwind, GE and Siemens’ wind turbines with
120 m towers are mostly prototypes.
51
Solar PV technologies are divided into crystalline silicon, thin-film and new cell technologies according to the cell material and
manufacturing process used.
1. Crystalline silicon cell technology. This is the
mainstream technology at present. It includes
monocrystalline and polycrystalline silicon.
Crystalline silicon cell manufacturing is
becoming more and more diversified. Aluminium back surface field monocrystalline
and polycrystalline silicon cells are manufactured at scale, and their average conversion
efficiency has reached 19.8% and 18.5%
respectively. The conversion efficiency of the
monocrystalline and polycrystalline silicon
cells using passivated emitter rear cell
(PERC) technology is about 0.5 percentage
points higher. With rapid technological progress, N-type crystalline silicon cells have
entered small-scale production. The conversion efficiency of monocrystalline and polycrystalline silicon cells, with a new structure
and using new technologies, could be
improved substantially in the future. N-type
crystalline silicon cells using passivated
emitter rear totally diffused (PERT) technology, heterojunction with intrinsic thin layer
cells (HIT), interdigitated back contact
(IBC) solar cells and other back contact cells
will be the future trends.
2. Thin-film cell technology. Industrial-scale
thin-film cell technologies have gradually
matured and have bright prospects. Thin-film
cells include silicon-based thin film, copper
indium gallium selenide (CIGS), cadmium
telluride (CdTe) and gallium arsenide (GaAs).
The innovation space of silicon-based thin
film cell technology is limited, with market
share decreasing in recent years. Currently,
CdTe and CIGS thin-film cells are mainstream, with the highest conversion efficiency
in laboratory testing exceeding 22%. Mass
production of GaAs cells has not been
achieved due to high costs.
CSP technologies are divided into trough,
tower, dish-Stirling and linear Fresnel.
Trough CSP. Trough is the first CSP technology to be commercialised and has the largest
share of commercial CSP plants globally. The
current status of this technology is: (i) trough
CSP has a simple design and is low cost;
(ii) multiple concentrating heat collectors
(troughs) can be connected in series or in parallel
to form a large-capacity CSP system; (iii) its
concentration ratio is low, typically 50–80 suns,
and it is difficult to increase the temperature of its
heat transfer medium, which is usually around
400 °C; and (iv) due to the long heat transfer
loop, trough CSP loses large amounts of heat and
has a low system efficiency of about 11–15%.
Tower CSP. The current status of this technology is: (i) a tower CSP system has a high
concentration ratio of 300–1,000 suns and a high
system operating temperature of 500–1,400°C;
(ii) thanks to its short heat transfer loop, tower
CSP systems have small heat loss and a high
system efficiency of about 14%; (iii) tower CSP
is suitable for large-scale and large-capacity
commercial applications; and (iv) the system is
costly and requires heavy capital investment, and
its design and control system are complicated.
Dish Stirling CSP. The current status of this
technology is: (i) it has a high concentration ratio
of around 1,000–3,000 suns and an operating
temperature close to 1,000°C. Its peak conversion net efficiency can reach 30%; (ii) the
capacity of a dish Stirling system is usually
5–50 kW, with unit costs high; and (iii) the cost
of generating power does not depend on the size
of the project, as the plant can be used as a distributed power system or a megawatt-level power
station connected to the grid.
Linear Fresnel CSP. Linear Fresnel is a simplified version of trough CSP. The current status
of this technology is (i) it uses flat tracking
51
Stage Grid Energy Research Institute Co. Ltd., Analysis
Report on Power Generation with New Energy in China,
2017, pp. 36–39.
Special Report 3: A Study of China’s Technology Revolution
341
120 m towers weigh only 226 tons, 30% lighter
than other all-steel or steel-concrete towers.
Goldwind, GE and Siemens’ wind turbines with
120 m towers are mostly prototypes.
51
Solar PV technologies are divided into crystalline silicon, thin-film and new cell technologies according to the cell material and
manufacturing process used.
1. Crystalline silicon cell technology. This is the
mainstream technology at present. It includes
monocrystalline and polycrystalline silicon.
Crystalline silicon cell manufacturing is
becoming more and more diversified. Aluminium back surface field monocrystalline
and polycrystalline silicon cells are manufactured at scale, and their average conversion
efficiency has reached 19.8% and 18.5%
respectively. The conversion efficiency of the
monocrystalline and polycrystalline silicon
cells using passivated emitter rear cell
(PERC) technology is about 0.5 percentage
points higher. With rapid technological progress, N-type crystalline silicon cells have
entered small-scale production. The conversion efficiency of monocrystalline and polycrystalline silicon cells, with a new structure
and using new technologies, could be
improved substantially in the future. N-type
crystalline silicon cells using passivated
emitter rear totally diffused (PERT) technology, heterojunction with intrinsic thin layer
cells (HIT), interdigitated back contact
(IBC) solar cells and other back contact cells
will be the future trends.
2. Thin-film cell technology. Industrial-scale
thin-film cell technologies have gradually
matured and have bright prospects. Thin-film
cells include silicon-based thin film, copper
indium gallium selenide (CIGS), cadmium
telluride (CdTe) and gallium arsenide (GaAs).
The innovation space of silicon-based thin
film cell technology is limited, with market
share decreasing in recent years. Currently,
CdTe and CIGS thin-film cells are mainstream, with the highest conversion efficiency
in laboratory testing exceeding 22%. Mass
production of GaAs cells has not been
achieved due to high costs.
CSP technologies are divided into trough,
tower, dish-Stirling and linear Fresnel.
Trough CSP. Trough is the first CSP technology to be commercialised and has the largest
share of commercial CSP plants globally. The
current status of this technology is: (i) trough
CSP has a simple design and is low cost;
(ii) multiple concentrating heat collectors
(troughs) can be connected in series or in parallel
to form a large-capacity CSP system; (iii) its
concentration ratio is low, typically 50–80 suns,
and it is difficult to increase the temperature of its
heat transfer medium, which is usually around
400 °C; and (iv) due to the long heat transfer
loop, trough CSP loses large amounts of heat and
has a low system efficiency of about 11–15%.
Tower CSP. The current status of this technology is: (i) a tower CSP system has a high
concentration ratio of 300–1,000 suns and a high
system operating temperature of 500–1,400°C;
(ii) thanks to its short heat transfer loop, tower
CSP systems have small heat loss and a high
system efficiency of about 14%; (iii) tower CSP
is suitable for large-scale and large-capacity
commercial applications; and (iv) the system is
costly and requires heavy capital investment, and
its design and control system are complicated.
Dish Stirling CSP. The current status of this
technology is: (i) it has a high concentration ratio
of around 1,000–3,000 suns and an operating
temperature close to 1,000°C. Its peak conversion net efficiency can reach 30%; (ii) the
capacity of a dish Stirling system is usually
5–50 kW, with unit costs high; and (iii) the cost
of generating power does not depend on the size
of the project, as the plant can be used as a distributed power system or a megawatt-level power
station connected to the grid.
Linear Fresnel CSP. Linear Fresnel is a simplified version of trough CSP. The current status
of this technology is (i) it uses flat tracking
51
Stage Grid Energy Research Institute Co. Ltd., Analysis
Report on Power Generation with New Energy in China,
2017, pp. 36–39.
Special Report 3: A Study of China’s Technology Revolution
341