The wake-up of the CPV technology

The wake-up of the CPV technology
By Dov Raviv
President and Chairman of MST
10 Oppenheimer Street, Rabin Park Rehovot, Israel
dovraviv@netvision.net.il ; www.mst-ren.com
Presented at the Electricity 2013 Conference in Jerusalem, 23-24 October 2013
The CPV technology was available for construction of solar plants since 2010, but its success
was limited in getting contracts. There are a limited number of companies worldwide that are
capable of building large utility size solar plants, namely Amonix, Sol Focus Emcore and Soitec.
MST has developed the CPV technology and the production lines for its CPV technology to
produce solar plants and is selling it world wide. Actually two large contracts have been signed
in China and US and a large solar plant is under negotiation in Israel. The two companies that
have bought the technology will soon join the companies already in the market.
The present reigning photovoltaic technology is based on silicon solar cells. The CPV technology
is based on Multi Junction solar cells that have double the efficiency of silicon solar cells.
CPV is superior to PV in hot climates and high DNI (Direct Normal Irradiation) areas.
A rising interest in installing CPV solar plants is seen in territories where CPV has advantage
over PV due to its larger production per KW installed, saving on land area, providing dual use of
land, producing double energy per land area than tilted PV, saving on cleaning expenses due to
its elevated position above ground and the resulting low LCOE (Levelized Cost of Energy).
Israel, US, South Africa, Namibia, China, Chile and Australia are some of the countries
interested to install large solar CPV power plants.
What is CPV
CPV is the technology that uses MJ (multi junction) solar cells that was originally developed for
space application and concentrated light to reduce the size of the solar cells and thus reduce cost.
The industrial MJ solar cells have today an efficiency of 40% and will reach in about 3 years an
efficiency of 45%. In the more distant future the MJ cells will reach an efficiency of 50%.
The increase in efficiency of the cells is of great interest because it reduces proportionally the
entire cost of the CPV system.
The light concentration of present systems varies between 500 and 1000 suns. The size of the
lenses varies from 30x30 cm to 5x5 cm.
The high concentration requires accurate tracking of the sun, normally better than 0.1deg. The
tracker is a critical element in the CPV system, because degradation of tracking will reduce
strongly the efficiency of the system. The tracker becomes also a significant cost item and its
MTBF/failure rate is critical.
The below figure depicts the typical concentration configuration of CPV.
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Resource available to CPV
Light energy is comprised of two elements: DNI (Direct Normal Irradiation) and diffusive.
The resource available to CPV is only the DNI.
The DNI contains about 80% of the available light energy.
However, because CPV tracks the sun, it captures all the DNI available, in contrast to PV fixed
systems that capture only part of it.
Resource available to Silicon PV
Silicon PV captures the normal component of the DNI and the diffusive light.
Thus, about 25%-30% of the DNI is lost for fixed latitude tilted silicon PV systems because of
cosine losses.
Other differences between Silicon and MJ systems
There are two other major parameters that make a difference between silicon and MJ/CPV
systems.
1. The efficiency reduction due to cell temperature
The typical efficiency loss figure for silicon panels is 0.38%/degK
The typical efficiency loss figure for MJ cells is 0.06%/degK
Thus, the efficiency loss of CPV cells due to temperature is significantly lower than that of silicon.
2. The efficiency decay over time.
The typical figure for silicon panels is 20% over a 25 years period, namely 0.8%/year
The typical figure for CPV is 5% for 25 years namely 0.2%/year. This figure is one quarter of the
silicon figure.
Areas of CPV advantage over PV
From above one can see that CPV will have advantage over Fixed Tilt PV in areas of high
radiation and high temperature.
In addition, over a 25 years period, the CPV will produce 7.5% more energy due to lower
efficiency loss over time. This is a very significant benefit of the CPV over PV.
Five examples spread over the entire globe will demonstrate these facts. The Resource radiation
is taken from NASA world database that is averaged over a period of 22 years.
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Location #1: Dimona, Israel, Lat= 31.069; Lon=35.033
DNI=2182.7 kwh/msq/year
Dimona Radiation Monthly Production (kwh/msq/month)
250.00
200.00
150.00
100.00
50.00
0.00
1
2
3
CPV
4
5
6
7
PV Tilted
8
9
10
11
12
Month
Figure 1
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Dimona Monthly Excess Energy Produced by CPV (CPV/PV-1)
160.0%
140.0%
120.0%
100.0%
80.0%
60.0%
40.0%
20.0%
0.0%
1
2
3
4
TPV/PV Ratio
5
6
7
8
9
10
11
Yearly average
12
Month
Figure 2
Location #2: DeAar, South Africa, Lat=-30.659; Lon=24.013
DNI=2719.3 kwh/msq/year
DeAar Radiation Monthly Production (kwh/msq/month)
250.00
200.00
150.00
100.00
50.00
0.00
1
2
3
CPV
4
5
6
PV Tilted
7
8
9
10
11
12
Month
Figure 3
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DeAar Monthly Excess Energy Produced by CPV (CPV/PV-1)
140.0%
130.0%
120.0%
110.0%
100.0%
90.0%
80.0%
70.0%
60.0%
50.0%
40.0%
30.0%
20.0%
10.0%
0.0%
1
2
3
CPV/PV Ratio
4
5
6
Yearly average
7
8
9
10
11
12
Month
Figure 4
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Location #3: Tibet Plateau, Lat=29.5; Lon=91
DNI=2606.1 kwh/msq/year
Tibet Plateau Radiation Monthly Production (kwh/msq/month)
250.00
200.00
150.00
100.00
50.00
0.00
1
2
3
4
CPV
5
6
7
8
9
10
PV Tilted
11
12
Month
Figure 5
150.0%
Tibet Plateau Monthly Excess Energy Produced by CPV (CPV/PV-1)
140.0%
130.0%
120.0%
110.0%
100.0%
90.0%
80.0%
1
2
3
CPV/PV Ratio
4
5
6
Yearly average
7
8
9
10
11
12
Month
Figure 6
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Location #4: Hohhot representative of Inner Mongolia in China, Lat=41; Lon=112
DNI=2193.7 kwh/msq/year
Hohhot Radiation Monthly Production (kwh/msq/month)
250.00
200.00
150.00
100.00
50.00
0.00
1
2
3
CPV
4
5
6
7
8
9
10
11
PV Tilted
12
Month
Figure 7
Hohhot Monthly Excess Energy Produced by CPV (CPV/PV-1)
150.0%
140.0%
130.0%
120.0%
110.0%
100.0%
90.0%
80.0%
1
2
3
CPV/PV Ratio
4
5
6
Yearly average
7
8
9
10
11
12
Month
Figure 8
Location #5: Alice Springs in Australia, Lat=-24; Lon=134
DNI=2613.4 kwh/msq/year
The average yearly CPV/PV =125.4%
For reason of brevity we do not present the detailed monthly information
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One can see that for a DNI of about 2200 kwh/msq/y the CPV produced energy has an advantage
of about 20%-23.6% over Fixed tilt PV, for a DNI of about 2600 kwh/msq/y the CPV produced
energy has an advantage of about 26% over Fixed tilt PV and for a DNI of about 2700
kwh/msq/y the CPV produced energy has an advantage of about 30% over Fixed tilt PV.
The five examples that we brought above represent different high DNI locations all over the
world.
For low DNI locations Silicon Fixed Tilt PV technology dominates, therefore there is no reason
to install CPV in such locations.
Summing up, the following regions are the most favorable regions for installation of CPV:
South West US, North Mexico, Chile, North Argentina, South Africa, Tibet Plateau, Inner
Mongolia, Australia, North Africa and Middle East countries including Israel.
Figure 9 depicts a more complete picture of high radiation regions all over the world.
Figure 9
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CPV vs Tilted PV land use
CPV requires an area of 8,000msq/MW up to 12,000msq/MW.
Tilted PV requires 20,000 to 40,000 msq/MW and CSP (Thermal Concentrating systems)
requires 35,000 msq/MW.
Thus CPV requires about half the land of Fixed tilted PV and one third of CSP.
CPV can be installed on hilly areas because it is mounted on a pole. PV requires flat areas.
This constraint is a major issue when looking for land. This is specifically true for areas as Tibet
Plateau which is a major solar energy asset for China.
Land is always a rare commodity, and it should be used sparingly.
For large installations at the level of a country, a low land area requirement is a major benefit.
Israel is a good example.
To provide 80% of Israel’s electricity need, one should install 45,000MW that will require about
450 kmsq of land.
A Tilted PV installation will require double the land area, namely 900kmsq. Moreover, the land
needs to be flat. It will be impossible for Israel to allocate 900Kmsq for a solar power plant.
CPV vs Tilted PV Dual use
CPV is installed on trackers that have a minimum clearance of 2m off ground.
This allows using the land for dual use in agriculture or others.
CPV advantage regarding soiling
CPV is installed on trackers that have the platform elevated 6m off the ground with a clearance of
at least 2m from the ground. This setup reduces significantly soiling due to wind that raises dust
from the ground.
Thus, the task of cleaning the panels, which is the major maintenance cost element, will be
reduced significantly. For the same investment in cleaning it may result in an efficiency saving of
10% of the energy production.
This is specifically acute in sandy regions which are characteristic of the CPV installations.
Productivity of CPV vs Fixed tilt PV
The CPV uses less than half the land required by PV and produces 20% to 30% more energy per
KW installed, therefore it will produce at least 2.4 to 2.6 times more energy per unit land than
Fixed tilt PV.
At the end of the day one looks for the amount of energy produced per land used, therefore this
parameter has a major importance when choosing the solar energy technology in a certain
country.
CPV uses to the maximum the land resource of a country in comparison to Fixed tilt PV or
thermal concentrating (CSP) systems.
Cost effectiveness of CPV
The CPV systems have reached the stage that large turnkey solar plants can be sold at a price of
$2500/KW.
High quality fixed tilt PV systems are now sold for a price of about $2000/KW. Having an
advantage of 20%-30%, the CPV installations are as cost effective as the PV systems.
Taking into account the additional advantages of the CPV, it becomes the system of choice in
desert areas (hot and high radiation) as well as in high altitude areas that have high radiation and
may not be particularly hot like in the Tibet Plateau.
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Moreover, as the efficiency of MJ solar cells increases, the cost and therefore the price of CPV
installations will reduce proportionally. In addition, as the installation capacity of CPV increases,
the price of components will decrease as well.
In view of above, we can easily anticipate a reduction of 25% in CPV price in the next 5 years to
a price below $2000/KW. At that stage CPV will be the most cost effective solar system
technology to install in the relevant territories.
The MST Business Model
MST anticipated in 2002 that CPV will be the technology of the future that will achieve a price of
$2000/KW and therefore reach grid parity. At that time the price of PV installations was
$6000/KW up to $8000/KW.
In 2007 MST got an investment and developed the CPV that was completed in 2009. In the
process we came to the conclusion that the market for CPV is of large utility size power plants
and that high production capacity will be required for the technology to be relevant. At the very
beginning of the development we approached several production line contenders to design for us
a highly automated production line and we finally chose KUKA from Germany. KUKA is a
major designer and supplier of turnkey assembly lines for the automotive industry. Incidentally,
at that period KUKA decided to enter the solar energy market.
During a series of technical meetings with KUKA we modified the design of the system to suit
the technologies mastered by KUKA. This activity resulted in design of a series of production
line capacities ranging from a fully automatic design of 1500MW/year and up to 75MW/year
automated production line.
In parallel we designed together with Ortec, an Israeli company, an assembly line of Power
Elements (about 5 million units per year) compatible with production capacity of the 75MW/y
production line designed by KUKA.
Having the design of the two production lines available, we could offer to customers a product
that no other CPV company offers, namely a proven technology with a production capacity that
will satisfy the demand for large utility size CPV power plants.
In fact we have contracts signed with two customers for technology transfer and supply of
production lines of 375MW/y and 600MW/y.
In addition we are in negotiation to build a 100MW CPV plant, for which we shall build a
75MW/y production line in Israel, probably at the premises of Flextronics.
Our business approach will allow building production lines in countries that give preference to
CPV technology and that want to have local production capability.
Epilog
The advantage of CPV technology in certain locations across the globe has finally been grasped
by the relevant customers and we see an interest rise to acquire the technology and install CPV
solar plants. In contrast to the silicon PV technology which is regarded today as a commodity, the
CPV technology is regarded as the next high technology that will penetrate the market in the
locations where it has merit.
In the next few years we shall see a significant increase in demand for CPV installations.
The actual worldwide capacity of a few hundred MW/year will very fast be saturated and a
demand for production capacity will be felt.
MST is able and willing to provide its technology and build production capacity to customers
wherever it is needed.
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