The cost of solar energy is more important than efficiency

Solar energy is clean and inexhaustible. Most renewable energy sources such as wind energy, water potential energy, and biomass energy are all indirectly converted from solar energy. The currently dominant fossil energy sources such as coal, oil, and natural gas also come from ancient biomass energy. Therefore, it is not an exaggeration to say that solar energy is the most important and promising renewable energy source.

However, China's solar power generation capacity is less than 0.1% of the total power generation, which is extremely incompatible with the status of solar energy. The main reason is that solar energy utilization devices have low efficiency and high costs, and economics cannot compete with conventional energy sources.

So what is more important than efficiency and cost? There are many different opinions on this issue. Some companies have declared that "to be the best in solar energy." Emphasizing that solar energy needs high performance and high quality. Of course, this is understandable for some companies. However, it does not work for the entire industry strategy. Mercedes-Benz may only be owned by a few people and it is impossible to run Mercedes-Benz on the street. The solar industry can make money if it is a minority business like the luxury goods industry. However, if it is not universally available, it will not be able to solve the problem of carbon emissions, nor will it solve the problem of sustainable energy development. The improvement of conversion efficiency should be based on the premise and basis of cost reduction. Blindly pursuing efficiency gains is likely to outweigh the benefits.

Electricity can be transmitted over long distances. This means that a variety of energy sources that are very far away from each other: thermal power, hydropower, nuclear power, wind power, etc. can all compete on the same starting line. If solar power is not economical for a long time, it is unimaginable to rely entirely on government subsidies for survival. The government itself does not make money, and almost all income comes directly or indirectly from taxpayers. No taxpayer will tolerate long-term taxation of his own taxes and eventually become a profit for foreign companies. Therefore, investing heavily in existing technologies that cannot significantly reduce prices is entirely based on the fate of the company.

Photovoltaic components are even more important in reducing costs. The volatility of solar energy is very large, and the average solar power is only one-fifth of the peak power. Therefore, the same amount of photovoltaic power generation needs five times the installed capacity of thermal power. Moreover, it is difficult to store electrical energy. It is impossible to generate electricity in the dark and rainy days. It also needs to invest in additional energy storage devices and smart grids, and pay for expensive energy storage and dispatching costs. Photovoltaic devices also have problems with life and efficiency degradation. All of this requires that photovoltaic power generation significantly reduce costs.

In the cost of electricity generation, not only the cost of the solar photovoltaic thermal device itself, but also the management cost, land cost, capital cost, installation and construction cost, and clean maintenance cost should be included. The increase in the conversion efficiency of photovoltaic modules is just one of them. To concentrate most of the energy and expenses on this aspect, it is most likely that the sesame seeds have been lost.

According to recent statistics, the price of polysilicon has fallen by more than 93% from 475 US dollars/kg three years ago to about 30 US dollars/kg. Formerly known as the "support silicon is king" has undergone major changes. In the era of high-priced polysilicon, many of the technical means for reducing the amount of crystalline silicon and increasing the utilization of crystalline silicon have become obsolete. For example, there has been a tendency to reduce the thickness of silicon wafers and reduce the amount of crystalline silicon. The thickness of photovoltaic wafers has been reduced from the original 330 μm to the current 200 μm. Many expect that this trend will continue and the wafer thickness will become 100 μm or even lower. Obviously, when the unit price of crystalline silicon is greatly reduced, is it necessary to reduce it to such a low level?

The same is true for improving conversion efficiency. Increasing conversion efficiency also reduces the amount of polysilicon used, but is it worth the price of silicon at this point? The earliest photovoltaic cells were inefficient, only a few percent. Therefore, it is of great significance to increase conversion efficiency. However, the closer it is to theoretical efficiency, the more difficult it is to raise and the less likely it is to reduce costs. In order to increase efficiency, many complicated processes are used. Although the technology is advanced, the cost is too high. If just to reduce the shadow of a little bit of the gate line and increase a little bit of efficiency, then with the substantial price reduction of crystalline silicon materials, the increased cost can buy a larger area of ​​medium-efficiency photovoltaic cells and emit more electricity. Of course, in areas with high labor costs, the improvement of conversion efficiency can reduce system installation costs, which is of positive significance. However, many new quick-install devices also reduce system installation costs. Therefore, it is still necessary to comprehensively consider what kind of combination system overall cost can reach the minimum.

Moreover, even if the efficiency of each wafer is increased while the cost remains the same, is the reduction in cost per watt sufficient to drive the market? The recent drop in the price of module components is very rare and even exceeds the maximum limit that may be achieved by individual efficiency improvements. The tragedy is such a large decline that still fails to usher in the expected explosive growth in the installed capacity. This is also the reason why some photovoltaic companies in Europe and the United States, known for their advanced technologies, have failed one after another. Efficiency in the market has been lost to cost. At present, the price of components has fallen by about 50%. Assuming that the original efficiency is 17%, even if it can increase 10% to 18.7%, the price will be reduced from the original 50% to 55%. Although there are certain cost advantages over competitors, there is no essential difference. Such a decline in competition with traditional coal or electricity is still not enough.

The development of the solar energy industry is now facing a bottleneck. Part of the reason is that the relationship between cost and efficiency has not been properly dealt with. In the end, there has been a deviation in the choice of the technical route. At present, the most widely used solar energy industry is not photovoltaic power generation but agriculture, and the efficiency of photosynthesis is only about 1%. If you count the factors such as sparse plants in winter and growing season, the actual efficiency is even lower. The reason why agriculture can be widely used is that the cost is very low. Always keep in mind that for solar applications costs are more important than efficiency.