By Zhang Yongwei, General Office, the DRC

Research Report No 69, 2009

I. Photovoltaic Industry Quickens Technological Advance and Improves Economic Efficiency

1. Photovoltaic industry quickens technological advance and expects new technological breakthroughs

(1) Continuous breakthroughs have been made in the conversion rate of polycrystalline silicon and the thinning technology of silicon wafers. To the polycrystalline silicon solar cells which now claim a 90% share of the photovoltaic market, higher conversion rate and thinner silicon wafers represent the main ways to cut cost. Since 2004, the conversion rate of polycrystalline silicon cells has risen rapidly from 14.5% to 16.5%, thus reducing the cost of solar cell systems by 14%. In the meantime, the thickness of silicon wafers has reduced drastically from 300um to 170um and the consumption of silicon materials has dropped sharply from 12kg/kw to 8.5kg/kw. As a result, the cost of silicon materials has fallen by about 30%. The latest experimental data indicate that the efficiency of polycrystalline silicon solar cells can reach 20.3% and the efficiency of monocrystalline silicon solar cells can reach as high as 24.7%.

(2) Thin-film cell, back-contact cell, concentrator solar cell, automatic-tracking flat solar cell and other new technologies have appeared and are competing with each other. The thin-film solar cell is made by coating a several-um-thick layer of photosensitive material on a cheap glass, stainless or plastic base. Compared with the crystalline silicon solar cell whose thickness is close to 180~200 um, the thin-film solar cell is only several um thick, or just about 1% of the thickness of the former. It can reduce the cost of solar cell from 2.5 dollars/W to just 1.2 dollars/W. Currently, the conversion rate of thin-film solar cell has also gone up sharply, with the conversion rate of commercialized products reaching 11% and the highest laboratory rate reaching 19.9%. Thin-film cell has entered the stage of application and industrialization. The technology of back-contact cell has also reached the degree of industrialization, with the conversion rate being able to reach 20% and the highest laboratory rate 26.8%. The technology of concentrator solar cell uses a concentrator to condense sunlight from a fairly large area to a fairly small scope so as to form a "focal spot" or "focal strip". Placing a solar cell on the focal spot or focal strip can increase light intensity and overcome the low energy flux density of solar radiation. This technology can acquire greater output of electric energy, with the highest laboratory conversion rate being able to reach 40.7%. Although this technology has to further improve its economic efficiency and solve other problems, it is expected to enter the stage of industrialization soon. The automatic-tracking flat solar cell system is based on the existing monocrystalline or polycrystalline silicon cells. As the automatic-tracking technology can enable the cell to target on the sun, it can increase the system’s power generation by 20%~50%. The automatic-tracking flat solar cell system can very likely become the mainstay of future photovoltaic power generating systems.

2. The fast drop in cost of photovoltaic products has accelerated pace of mass industrialization

As a result of the co-action of technological advance, wider application and falling prices of raw materials, the cost of photovoltaic power generation has been falling rapidly year after year. At present, the price of polycrystalline silicon which accounts for nearly 40% of the total cost of photovoltaic components has dropped from 250 dollars/kg in 2006 to 140 dollars/kg in 2008, and the cost of photovoltaic power generation has dropped to 2.3~1.7 yuan/kwh. It still has a vast room to drop. This speed of decline has far exceeded the past expectations of many academic institutions and investors. Currently, some authoritative institutions in the world are very upbeat about the future cost of photovoltaic power generation, with the most optimistic forecast believing that the cost will drop to 1.0~0.7 yuan/kwh by 2015. In other words, the cost of photovoltaic power generation can drop to the level of traditional electric power in about five years. Chinese photovoltaic enterprises such as Shangde and Tianhe say they can reduce the cost to 1.0 yuan/kwh in about three years.

3. Photovoltaic industry is not "energy-consuming" or "high-polluting" industry

People often define the photovoltaic industry as an energy-consuming one on the ground that refining one ton of polycrystalline silicon has to consume 160,000 kw/h of electric power. This view is lopsided. In terms of energy consumption for per unit of output value, the energy consumed for 10,000-yuan component output value (including the refining of polycrystalline silicon) under the existing technological conditions is about 900 kw/h. The energy consumption for per unit of output value of the photovoltaic industry is far lower than the steel and electrolytic aluminum industries. In terms of the total lifecycle energy consumption of photovoltaic products, the photovoltaic products are energy products that consume energy in the course of production and produce energy in the course of use. They produce more energy than they consume. In 2009, one kw of crystalline cells consume about 2,600 kw/h and can generate 1,300kw/h a year on average after being installed and put into operation. That means the energy consumed in the course of production can be recovered in about two years. Based on a 20-year service life (the service life is generally believed to be 25~30 years), one kw crystalline cells can produce net energy for at least 18 years, or 23,400kw/h. In terms of its share of total national electric power consumption, even if the output of the photovoltaic industry nationwide reaches 30GM by 2020, the total annual electric power consumption will be about 52.5 billion kw/h or 0.69% of the total electric power consumption nationwide. On the other hand, the electric power consumption by the iron and steel industry in 2008 was abut 394 billion kw/h, accounting for 9.8% of the country’s total electric power consumption; the electrolytic aluminum industry consumed over 150 billion kw/h of electric power in 2008, or 4.5% of the country’s total electric power consumption. In short, it is unscientific to use the energy consumption for per ton of polycrystalline silicon alone to define the photovoltaic industry as an energy-consuming industry. At present, the energy-consuming crystalline silicon enterprises are those with outdated production capacities and should be eliminated. The energy consumption for per ton crystalline silicon by all the mainstream crystalline silicon enterprises is bellow 140,000kw/h. And technological advance is further drastically reducing the energy consumption for per ton of polycrystalline silicon.

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