Concerns about the development of solar LED street lights

1. Human beings are still indifferent to the serious consequences of atmospheric warming.

The gradual warming of the atmosphere is an indisputable fact, but people still have a poor understanding of its seriousness. The concentration of carbon dioxide in the atmosphere has increased by 25% in the last 200 years, causing the average temperature of the Earth to rise by 0.5oC (Fig. 1).

And after entering the mid-1980s, the rate of increase is accelerating, which can be said to be mainly China's contribution, because China is already the country with the largest carbon dioxide emissions in the world. In the next few decades, the doubled concentration of carbon dioxide will cause the average temperature of the earth to rise by 3-5 degrees, and the polar regions will rise by 10 degrees. The greenhouse effect will consume 5%-20% of the national economy; the ice layer of the Arctic Ocean is disappearing at a rate of 8% per decade, shrinking 2 million square kilometers within one year, and will disappear completely after 2040, polar bears also Will be extinct. And will also make:

1. Sea level rises 6 meters; in 2050 some coastal cities (such as New York, Shanghai) will be inundated

2. Anomalous climate and increased ocean storms;

3. The land is dry and the desertification area is increasing (Beijing will be desertified);

4. Increased pests and diseases on the earth;

5. The frozen billion-year virus will inspire

In his recent speech, the UN Secretary-General pointed out that the greenhouse effect of the Earth has threatened the survival of mankind, and its threat level is no less than terrorism, because the threat of terrorism is limited to specific countries and regions. If no positive measures are taken, the greenhouse effect It will affect global humans in the near future and has nothing to do with the country. The Kyoto Protocol stipulates that from 2008 to 2012, the greenhouse gas emissions of major industrialized countries will decrease by an average of 5.2% on the basis of 1990, of which the EU will reduce the emissions of six greenhouse gases by 8%. The United States cuts by 7% and Japan by 6%.

The recent international climate talks in Copenhagen want to reach an international agreement including all countries to reduce carbon dioxide emissions, but it has evolved into a struggle between rich and rich countries, which the poor countries think is the cause of rich countries, but Poor countries come to eat this bitter fruit. In fact, China's annual carbon dioxide and sulfur dioxide emissions have ranked first in the world as early as 2006. We have been arguing in the past that your developed countries have been emitting for hundreds of years, and we have only begun to emit large amounts of emissions in recent decades. But now it is not about discussing the issue of the right to emissions, but how to save the world and all humanity, not to mention that China itself has already suffered enormous threats and losses. The average daily concentration of sulfur dioxide in 62% of cities in China exceeds the national third-level standard. The area of acid rain area in the country has accounted for 30% of the country's land area, and the losses caused by acid rain and sulfur dioxide pollution are more than 110 billion yuan/year. Every year, freezing disasters, typhoon disasters, droughts and even Wenchuan boycotts may be the result of atmospheric warming. Needless to say, seawater in Tianjin, Shanghai, and the Pearl River Delta is likely to invade in the future (the Pearl River Delta has already experienced a drinking water crisis invaded by seawater).

2. Solar energy is the best renewable energy source

70% of China's power generation relies on coal combustion, which emits a large amount of carbon dioxide and sulfur dioxide, which is the primary cause of the greenhouse effect. Therefore, it is imperative to completely change China's energy structure. Everyone knows that the two most important renewable energy sources today are solar energy and wind energy. In fact, wind energy is also a kind of solar energy, and it has a large regional and seasonal, so the most basic is solar energy. Solar energy is the inexhaustible source of renewable energy. The sun's rays illuminate the earth for 40 minutes, which is equivalent to one year of global energy consumption.

The United States has proposed an ambitious plan to provide solar power to provide 69% of US electricity and 35% of its total energy (including transportation) by 2050. If wind, biomass and geothermal energy are also being developed, renewable energy can provide 90% of US electricity and other energy by 2100. In 2008, the installed capacity of solar power in the United States has reached 357,000 kilowatts. In the close-range target, by 2012, renewable energy production will increase to 10% of power generation. In 2012, the installed capacity of solar power in the United States will increase by 16 million kilowatts, which is 5.8 times the annual increase in 2007.

China's National Development and Reform Commission announced the medium and long-term development plan for renewable energy. It is proposed that by 2010, the cumulative installed capacity of photovoltaic power generation will reach 300,000 kilowatts, accounting for only 0.05% of the previous year's thermal power generation. It will reach 1.8 million kilowatts in 2020, and recently plans to increase its capacity plan to 20 million kilowatts in 2020, which is only 3.6% of the previous year's thermal power generation. The actual deployment of solar power facilities in China reached 350 MW (350,000 kW) in 2009, accounting for 5% of the world. However, the production of solar panels produced in China has reached more than 40% of the world. That is to say, 86% of the solar panels produced in China are exported. Because solar power is an emerging industry, and it is still a loss-making industry, it is a planned economy, both Chinese and foreign, and has not yet entered the market economy. If the government does not order, it will not be sold. Therefore, China does not have no solar panel industry, but no solar power industry. The government is not willing to pay the bill.

However, solar power generation was originally a loss-making industry. Now conventional solar power generation is 4 yuan / kWh, and thin film solar power can reach 1 yuan / kWh. Moreover, the government does not have to make great efforts to develop the solar power industry. Let's see where the problem is!

3. It is difficult for China to rapidly develop solar power generation business according to foreign models.

At present, there are two main modes for the rapid development of solar power generation abroad. One is to build large-scale solar power stations in desert areas, and the other is to launch solar roof plans on a large scale. However, neither of these plans is suitable for China's national conditions.

1. Large-scale solar power plants need to occupy a large area, only in desert areas, while most of China's deserts are far from big cities, unlike Las Vegas in the United States, and China's nearest Dunhuang solar power station in Lanzhou is also good. A few hundred kilometers away, not to mention the big cities along the coast.

2. Large-scale solar power plants require great investment, such as another large-scale solar power plant recently signed in Hohhot, with a total power of 20,000 kilowatts, an investment of 1 billion yuan, and completed in 2010 after 10 months. Therefore, the 300,000 kilowatts planned by the National Development and Reform Commission will require 15 billion investment.

3. The fundamental problem is that the technology of large-scale solar power plants is still immature. Now the world's largest solar power station has only 46,000 kilowatts, and there are still a series of problems to be solved. It can be said that all current solar power plants have only exemplary functions, but have not yet had the economic value of large-scale promotion.

Another most successful German solar roof plan is indeed a good way to mobilize people to run solar power. Its basic plan is this. It is funded by individuals to build solar power installations on their roofs. The electricity generated by the state is bought at high prices and returned to the grid. In a few years, the full cost can be recovered. Therefore, California has also proposed the same solar roof plan. Once the plan is completed, California, known as the “Sunshine State,” will receive 3 million kilowatts of clean electricity per year, while reducing emissions of 3 million tons of greenhouse gases, which is equivalent to 1 million cars.

But it is difficult for China to promote this solar roof plan because most of the middle class in China that has the ability to build solar roofs live in high-rise apartments in big cities, most of which do not have their own roofs, and a few richer classes, although Villas, but most of them are not living there for a long time, and it is unlikely to invest in building solar power plants. As for the rural areas, although most farmers have their own roofs, they have the ability to build their own solar water heaters, and it is not possible to build solar power plants.

So, perhaps these reasons can explain why China cannot promote solar photovoltaic power generation on a large scale.

4. Solar Led Street Light is a big market

We know that global lighting uses 20% of all electricity, and a large part of it is used for outdoor lighting. China is no exception. According to statistics, there are about 200 million street lamps installed in China. The average power of the street lamp is about 200 watts. Assuming that the opening time is 10 hours per day, then 2 kWh per day, 730 kWh in 365 days, and 146 billion kWh in 200 million baht. The 26 units of the Yangtze River Three Gorges Hydropower Station, the largest hydropower station in China, have a power generation capacity of 84.7 billion kWh per year. Therefore, the electricity used by all street lamps is about 2 generating powers of the Three Gorges Power Station. This is by no means a small number.

What's more, the current street lights are still increasing at a rate of 20 million baht per year. Only about 90% of the current high pressure sodium lamps are used. Although its luminous efficiency is still very high, it has a short life span, high power consumption, low color temperature, poor color rendering, and also contains toxic substances such as mercury, which will be eliminated sooner or later.

Since the Ministry of Science and Technology has put forward the "Ten Cities and Ten Thousand Miles" plan to vigorously develop LED street lights. LED street lights are now growing at a rapid rate. It is a pity that more than 90% of the “Ten Cities and Ten Thousands” are still using LED street lights, or the existing high-pressure sodium lamps are LED street lights. According to conservative estimates, the total number of ten-city plans will exceed 2 million, but it is only one-tenth of the total number of new lights added each year. As mentioned above, if the newly added 20 million baht per year uses solar energy, its total power will reach 4 million kilowatts. In fact, it is far more than this, because the solar panel power used by solar LED street lamps is actually The lamp power is 3-4 times. Assuming three times, the total installed capacity of the solar panels will reach 12 million kilowatts. In 2008, the total output of solar panels in China was 1.78 million kilowatts (1780 MW). Still far from the need to supply solar street lights. This shows that the market for solar LED street lamps is by no means a market that is dispensable, but a big market that plays an important role.

V. Concerns about the development of solar LED street lights

So why are there still no large-scale development of solar LED street lights? There are some doubts:

1. The cost of solar LED street lights is too high. The cost of LED street lights is already high, and the cost of solar LED street lights is even higher. This is mainly due to the high cost of solar panels. In fact, the unit price of solar panels is rapidly decreasing year by year. For example, the current unit price is about 10 yuan / watt (currently actually 12 yuan / watt, but next year it is possible to reduce to 10 yuan / watt, for the sake of simplicity of calculation, assumed to be 10 yuan / watt), about two years ago Half of it. For a 100-watt LED street light, even if it needs 300Wp solar panels, its cost is only 3,000 yuan. The 100-watt LED street lamp can replace 250-watt high-pressure sodium lamp and 250-watt street lamp. It is assumed that the lamp is turned on for 10 hours every day, then 2.5-degree electricity is used every day, and 912.5W is used for one year. If it is 0.8 yuan per degree, the annual electricity bill will be 730 yuan. After 4 years, the saved electricity costs can compensate for the cost of solar panels. In fact, the situation is far from the same. The savings from solar LED street lights are not primarily electricity, but cable costs and construction costs for buried cables. Take the 10 km (666 盏) AC circuit lamp, the cost of the cable is 1.5 million yuan, and it is 2252 yuan for each lamp. It is also necessary to add 300,000 yuan for the laying of buried cables, and 450 yuan for each squat, because every time a cable has a voltage drop, it needs to use transformer boosted power transmission and distribution equipment and other equipment 2 million yuan, distributed to each A trip is 3003 yuan, all these costs add up to 5705 yuan, not yet calculated the inspection well 300 yuan / baht, and so on. All of this together has long exceeded the initial investment in solar LED street lights, so the electricity savings from solar LED street lights is a pure income.

From the above analysis, there is no need to worry about the high cost of solar LED street lamps.

2. In most places where there is insufficient sunlight, it is necessary to increase the area of solar panels. It is possible to use x5 solar panels, which are 500Wp solar panels, thereby increasing the cost and reducing the wind resistance.

This is indeed a problem. However, it is not a problem that cannot be solved.

The general Solar Street Light is designed to take into account the solar panel power required to work more than 10 hours a night. However, in most cases, it is not necessary to illuminate 10 hours per night. In the middle of the night and after the middle of the night, there are very few pedestrians in the past, and in this case, the power operation can be reduced. In the past, when using high-pressure sodium lamps, it is very difficult to change the power of the sodium lamp arbitrarily. Now, after using LEDs, it is very easy to change the power and brightness, so you can use a program called automatic intelligence. Brighten the controller to brighten. This brightness adjustment is based on the local traffic flow statistics, which usually saves 70% of the solar panel area in some areas, so it is a very reasonable method of intelligent dimming. This intelligent dimming controller has been mass produced.

This originally required 500 watts of solar panels, and now only 150 watts is enough. One company has installed this system on Chongming Island in Shanghai, using x2 solar panels, which can work as usual in seven rainy weather.

Not only that, but the area of the solar panel can be further reduced. That is to use maximum power tracking (MPPT) technology. We know that solar cells have different output power and output voltage characteristics under different solar illuminations, and their typical characteristics are shown in Figure 3. However, when the solar panel is directly charged to the battery, the voltage of the solar panel must be higher than the voltage of the battery (for example, 12 V). Obviously, it can be seen from the figure that its output power is not the largest at this time. In order to make full use of the power of the solar panel, a so-called maximum power tracking device is added to the charging controller, which can operate at the maximum value of the output power curve at any (illuminance). In this way, about 30% of the benefits can be obtained, that is, the area of the solar panel can be reduced by 30%. In the previous example, only 105Wp of solar panels is needed, which greatly reduces the solar cell. The size of the board also increases the resistance to wind. More importantly, the cost was reduced and the cost was reduced from 5,000 yuan to 1,050 yuan. It is completely acceptable.

3. Battery problem

At present, most solar LED street lamp systems use lead storage batteries, and the general lead storage batteries do have short life and environmental pollution. The problem of short life can be solved with a colloidal lead battery or a wound lead battery. They not only use safety, but also have the advantages of small self-discharge, deep discharge resistance, excellent performance, long cycle life, low float charge voltage, small float charge flow and high reliability. However, there is still a problem of lead pollution. Recently, the lithium iron phosphate battery has developed rapidly, and its charge and discharge times can reach more than 2,000 times, which is more than 6 times that of ordinary lead storage batteries. And there is no environmental pollution problem, but the current price is still relatively expensive, and with the large number of adoptions, the price will also drop.

Therefore, it is an old concept to think that the cost of solar LED street lamps is too high, the endurance is poor, the wind resistance is poor, and the battery life is short. The new technology has completely solved these problems and cleared the obstacles for the rapid development of solar LED street lamps.

Vigorously developing solar LED street lights is a major event that is in line with China's national conditions and rapidly developing China's renewable energy. It is also a top priority for achieving energy conservation and emission reduction. And this can completely launch the work done by local governments at all levels and companies engaged in solar LED street lights. There is no need to do things like the construction of the Three Gorges Dam, which cost hundreds of billions and can be easily accomplished by immigrating millions. How can we not do this?

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