Technical difficulties in concentrating photovoltaic power generation system - News - Global IC Trade Starts Here 工业

Photocoupler

I. Introduction

The price of solar power systems has remained high! The main reason is because the density of solar energy is low! The average light intensity of the sun shining on the ground is 1 kW / square meter; the conversion rate of single crystal silicon can reach 23%, the polycrystalline can reach 16%, and the film can only reach 8%. The most efficient conversion of gallium arsenide cells can reach more than 35%, but the overall conversion efficiency of solar power systems made with gallium arsenide is only about 25%.

Therefore, in order to reduce the price of solar power generation system, increasing the solar light intensity is a good solution. To increase the light intensity, it is necessary to use a convex lens or a fluorescene lens or a reflector to concentrate the light; this can greatly reduce silicon and arsenic. The use of gallium, which reduces the price of solar power systems; this is the origin of CPV (concentrated photovoltaic power generation system).

Second, the technical difficulties of the CPV system

The principle of CPV solar power generation system is relatively simple. Why haven't several companies around the world made a particularly stable and cheap power generation system? In the CPV field, in principle, the higher the concentrating factor, the cheaper the cost is, but the use of concentrating will cause the following problems.

1, let single crystal silicon withstand higher concentrating light

Although gallium arsenide can withstand 1000 times light intensity, gallium arsenide is now expensive, and arsenic in gallium arsenide is highly toxic, making it impossible to significantly reduce manufacturing costs, and in an environmentally-friendly international environment. It is also impossible to use it in large quantities. In the end, it can only be monocrystalline silicon; but monocrystalline silicon can only withstand 3 to 5 times the light intensity, and 3 to 5 times the concentration of light in the CPV field can hardly reduce the cost. A substantial reduction in costs must reach around 10. In order to achieve 10 times the concentration of light, special monocrystalline silicon must be used.

2, heat dissipation:

Ordinary silicon photovoltaic panels can reach temperatures above 75 degrees at noon in summer. Ordinary silicon panels will blister at twice the sun's intensity, and will be 10 minutes at 5 times sunlight. Foaming, foaming at 10 times sunlight intensity for 5 minutes, the solar cell will be oxidized after foaming, and the efficiency will be greatly reduced in a short period of time, and the heat is uneven after foaming, often There is a battery chip that bursts, so the system is completely unusable.

If the solar panel uses aluminum or copper heat sink for natural heat dissipation, a large number of heat sinks are required, which is particularly expensive and expensive than silicon wafers; if forced air cooling is used, a large amount of electric energy is used, which is not worth the loss. And the life and reliability of the fan is not high. In order to achieve high reliability, there must be error checking and redundant setting, which will increase the cost several times. If the fan is broken at noon in summer, the whole silicon photovoltaic panel may be It was completely burnt out. If water cooling is used, the cost is not cheap. Water cooling is due to many pipelines and many connection points. Pumps are needed. The number of faults is inevitable. The reliability is not as good as air cooling. Of course, the efficiency of water cooling is higher than that of air cooling. However, it is not available in solar systems where the failure rate determines a one-vote veto.

3. Reflector:

Ordinary mirrors, plastic reflectors due to the different thermal expansion and contraction coefficient of the reflective layer and the skeleton layer (such as glass) will fall off in the outdoor 2-4 years of reflective surface, in the desert high temperature difference may be completely unusable for several months. And the reflectivity will slowly drop.

In addition, high-reflectivity thin aluminum plates are also available at home and abroad, but such aluminum plates cannot withstand hail and cannot be scrubbed. If the scrubbing causes permanent damage, the aluminum plate has a service life of about 8 years, and the reflectance is reduced year by year, 8 years. Basically, there is only 40% of the reflectivity, far less than the 25 years required by the solar system; the aluminum plate has a protective film, but the protective film is expensive and does not prevent hail, and cannot solve all problems. In addition, in order to reduce the cost, the aluminum plate is generally about 0.3 mm, which is particularly difficult to process and the processing cost is particularly high.

4, tracker:

Photovoltaic cells can only work in the focus of the concentrator, because the earth yang is rotating all the time, so the tracker must be used to ensure that the photovoltaic cell is in the focus of the concentrator; the tracker is one of the main systems of the CPV system, Without the tracker system, it can't run. In addition to ensuring that the system can operate, the tracker can average 30-40% more electricity than the system without tracking. However, the tracker is a mechanical structure. The operation will be faulty for many years, and there will be wear and tear. If the tracker fails, the system will not be able to run (no power is generated). If there is wear, the tracking accuracy will be reduced, because the CPV system is tracking. Accuracy is required. If the accuracy is reduced, the power generation system will not operate normally.

Third, the solution

In order to solve the problem of CPV solution system and master the core technology of CPV system, General Manager Chen Pingjian of Beijing Anxin Hi-Tech led his R&D team from March 2008. After more than two years of research, he invested millions of dollars in After countless failures, it finally satisfactorily solved the core technology of monocrystalline silicon 10 times concentrating light, and has obtained or applied for more than 8 patents.

1, let single crystal silicon withstand higher concentrating light

After many improvements, we have finally produced a monocrystalline silicon photovoltaic cell that can withstand 15 times the light intensity, and the power of the same type of cell is increased by 15%, far exceeding the world's similar products.