AC/DC conversion is the conversion of analog V (eg V = 5V) to digital D (eg D = 255). There are many types of analog/digital (AC/DC) conversions, such as count comparison types, successive approximation types, double integral types, and the like. The successive approximation type is often used in integrated circuit devices, and the basic working principle of AC conversion DC is briefly introduced.

The figure shows the structure of the successive approximation. The AC/DC converter is based on a DC/AC converter, plus a comparator, successive approximation register, set logic and clock. The conversion principle is as follows.

Under the control of the enable signal, the first selection logic is set to give the highest position of the successive approximation register “1”. After converting the DC/AC to an analog quantity, it is compared with the input analog quantity, and the voltage comparator gives the comparison result. If the input quantity is greater than or equal to the output of the D / A conversion, the comparator is 1, otherwise 0, the setting logic is modified according to the result of the comparator output to modify the contents of the successive approximation register, so it passes the analog quantity after D The /A transform continuously approximates the input analog quantity. The number of digital changes after several modifications is the amount of AC/DC conversion results.

Most currents approximate AC/DC use a binary search method, which first compares the 1/2 value of the maximum allowable voltage range with the input voltage value, ie up to “1”, and the remaining bits are “0”. If the search value is within this range, a value of 1/2 of the range is taken, that is, the second highest position is “1”. If the search value is not within this range, another 1/2 range of the maximum allowable input voltage value of the search value is sequentially executed, that is, the highest bit is “0”, and the search range is narrowed down. The range is 1/2 each time. An n-bit AC/DC conversion can be obtained by n comparisons. The successive approximation method has a faster conversion speed, so the integrated AC/DC chip mostly adopts the above method.

As can be seen from the figure, the AC/DC conversion needs to perform external start control signals and is divided into two types: pulse start and level start. Chips that use pulse-on-chip include ADC0804, ADC0809, and ADC1210. The chips that use level-on are ADC570, ADC571, ADC572, and so on. This start signal is provided by the CPU. When the AC/DC converter is activated, after n comparisons by the binary search method, the contents of the successive approximation register are the converted digital quantities. Therefore, after the AC/DC conversion is completed, the digital quantity must be taken from the successive approximation register.

To this end, the DC/AC chip specifically sets the conversion end signal pin, sends a conversion end signal to the CPU, notifies the CPU to read the converted digital quantity, and the CPU can detect the AC/DC conversion end signal or the inquiry mode by interrupt, and from A. The digital register is taken from the data register of the /D chip (ie, the successive approximation register in Figure 10-9).

Component attenuation, including LID (photoinduced attenuation, including LeTID), PID, attenuation due to aging of the package material and battery connections, is an important factor affecting module power generation. Recently, due to the heated discussion of the LeTID issue, the attenuation of PV modules has attracted more and more attention.

LeTID (light decay under high temperature conditions, typically 50-80 ° C) was found and is typically present in the polycrystalline PERC component. With the improvement of laboratory research, under certain conditions, single crystal P-type Cz, FZ and N-type A can be seen similarly on the silicon wafer. The LeTID mechanism is relatively complex. The root cause of LeTID may be: metal impurities such as Cu and Ni in silicon wafers, hydrogen entering silicon wafers from SiNx and AlOx, or a combination of hydrogen and impurities. Related mechanism debate,

Therefore, the outdoor demonstration of the State Key Laboratory of China Electric Apparatus Research Institute in Sanya, Hainan, and Turpan, Xinjiang (2016.10~2017.9) can provide an important reference for the industry (as shown in the above figure, the highest temperature is the monthly maximum temperature. Component backplane, temperature is the component. The average temperature of the component backsheet between 10 and 14 o’clock during the day answers the question of the first year of decay of the single crystal PERC component. Although the previously published results were primarily used to study power generation data, in practice, the component electrical performance parameters were accurately tested before and after sampling the components. The components purchased were from the first-line manufacturer and the initial power supply consistency was very good.

In the Sanya test site, the module’s average operating temperature is 40-50 ° C, the maximum operating temperature is about 70 ° C, the module experienced 14.5 months of high temperature, high humidity and outdoor exposure, and the single-chip PERC module relative to the initial power The average attenuation is 1.99. %, (relative nominal power attenuation is 0.93%), the open circuit voltage and short circuit current attenuation is small, mainly the attenuation fill factor FF. The initial power attenuation of the two polycrystalline components was 3.77% and 2.77% (3.26% and 0.53% relative to the nominal power attenuation), and the main attenuation was the attenuation of the short circuit current.

In the Turpan test site, the average daily temperature (10~14 hours) of the components in June to August can reach 50C or more, and the highest working temperature in August reaches 70C or more. After 14 months of high temperature, high radiation, dust and The higher the day and night, the seasonal temperature difference, the average single-chip PERC component is attenuated by 1.59% relative to the initial power, (the average attenuation is 0.58% relative to the nominal power). Compared with the Sanya empirical project, the attenuation of FF is reduced from 1.25% to 0.86%. The single crystal PERC component has a small attenuation dispersion. The attenuation of the two polycrystalline components relative to the initial power is 3.22% and 2.65%, and the main attenuation is still the attenuation of the short circuit current.

From the empirical results of the two bases, for this harsh outdoor environment, the aging attenuation of the components is much more significant than in the general mild environment, and the single-crystal PERC assembly (from LONGi) has better attenuation, indicating single crystal. PERC technology combined with low light attenuation technology can effectively cope with outdoor high temperature working conditions.

The dilemma of silicon wafer supply and demand imbalance has not yet found an effective balance method, and manufacturers will inevitably withdraw. Silicon chips are still the main target for maintaining cost operations, but the situation with upstream chips is relatively stable. Demand in the end market continues to heat up, perhaps giving the battery and component manufacturers a glimmer of hope. As the Chinese government’s policy directives are expected to push the market warmer, the already weak demand has gradually stabilized. I believe that in the next few weeks, this will be a getting better momentum.

Wafer

This week, only the price of overseas monocrystalline silicon wafers was driven by demand. Polysilicon wafer manufacturers have made price stability a major indicator and are no longer sold at prices below the cost of cash. Regarding utilization, regardless of single polysilicon, first-line manufacturers still have a large advantage, and small and medium-sized factories are more difficult under the double squeeze of price and capacity. At present, domestic monocrystalline prices remain at 3~3.10RMB / Pc, polycrystalline prices remain at 2.07~2.15RMB / Pc, and black silicon product prices remain unchanged at 2.2RMB / Pc. The single crystal in the overseas market is maintained at 0.38~0.390USD / Pc, the polycrystalline price is maintained at 0.254~0.269USD / Pc, and the price of black silicon product is slightly decreased to 0.305USD / Pc.

Silicon material

This week, silicon material prices are still running at low levels. Compared with second- and third-line small factories, first-line factories can slightly support prices. The newly opened low-cost production line has not yet reached full mass production, so there is a certain difference in supply and demand of cost calculation, which indirectly affects downstream purchase intention and price acceptance. After the low-cost production line is opened and the high-cost production line exits, it is estimated that the cost perception of the buyer and the seller will be the same, but the demand side still has the final price decision, because if there is no strong demand, the price is lower. To no avail. At present, the price of domestic polycrystalline materials is 73~82 yuan/KG, the average price is reduced to 75RMB / KG, the price of single crystal materials is 80~84RMB / KG, and the average price is reduced to 82RMB / KG. Overseas prices remain unchanged at 9~10.2USD / KG.

Components

The trading price of the parts market this week was basically flat. Although the polycrystalline products are quoted but the actual transaction is not much, the overall price is flat or even small. The turnover of single crystal components is even more intense, but it cannot push up the price due to the lack of urgent orders.

At present, China’s domestic polycrystalline (270W~275W) is maintained at 1.78~1.85RMB / W, the average price is reduced to 1.80RMB / W, and the high efficiency polycrystalline (280~285W) is maintained at 1.80~1.93RMB / W. In general, the price of single crystal (290~295W) is maintained at 1.83~1.96RMB / W, the high efficiency single crystal (300~305W) is kept at 2.12~2.20RMB / W, and the high efficiency single crystal crystal (> 310W) is kept at 2.20. RMB / W. above price. The average polycrystalline price in overseas markets was lowered to 0.215~0.270USD / W, the average price was lowered to 0.216USD / W, and the high-efficiency polycrystalline correction range was 0.220~0.275USD / W. Usually, the single crystal remained at 0.2420.360 USD / W, High-efficiency single crystals are maintained at 0.265 to 0.390 USD / W.

Cell

This week, the battery market is still focused on high-efficiency products, while domestic and foreign single-crystal PERC batteries are out of stock. Polycrystalline products have been able to stabilize prices due to increased demand. The visibility of global demand continues to rise and it is estimated that December will be better than November.

At present, the price of ordinary polycrystalline batteries in mainland China is 0.8~0.85RMB / W, the average single crystal price is 1~1.06RMB / W, the high efficiency single crystal is 1.12~1.17RMB / W, and the high efficiency single crystal (> 21.5% )slightly increased. Increase to 1.2~1.25RMB / W, the average price is raised to 1.22RMB / W. The price of double-sided battery is raised to 1.25~1.30RMB / W. The foreign general polycrystal is kept at 0.095~0.130USD / W, the general single crystal is kept at 0.121~0.129USD / W, high-efficiency single crystal is adjusted to 0.145~0.165USD / W, and the ultra-high efficiency single crystal (> 21.5%) is raised to 0.16~0.172USD / W.

China has become the world’s largest producer of photovoltaic glass. In addition to meeting the domestic market demand, China’s photovoltaic glass exports have also grown rapidly.

According to the statistics of China Photovoltaic Industry Association, in January 2016, China’s photovoltaic glass exports to Japan, the United States, Europe and other international markets, the number of about 129,900 tons, accounting for about one-third of total photovoltaic glass production, 7.74 year-on-year. If PV glass is exported in the form of PV modules, the export volume will far exceed this ratio. At the same time, China’s PV glass imports in January 2016 were only 934 tons. According to statistics, in 2015, 93% of the world’s crystalline silicon battery modules use photovoltaic glass produced in China.

From the installed capacity of PV modules, from 2010 to 2014, the global PV module installed capacity grew at an annual rate of 28.2%, from 17.2GW in 2010 to 46.5GW in 2014. In the same period, the compound annual growth rate for China’s PV modules was 106.9%, from 0.6GW in 2010 to 10.6GW in 2014.

In terms of PV module production, from 2010 to 2014, the global compound annual growth rate of PV module production was 21.1%, from 22.3GW in 2010 to 48.1GW in 2014. In the same period, China’s PV module production increased from 10.8GW in 2010, and in 2014 it was 34.5GW, with a compound annual growth rate of 33.7%.

As mentioned above, as the global installed capacity of photovoltaic power generation and the annual production of photovoltaic modules continue to grow steadily in the coming years, the demand for photovoltaic glass will continue to grow.

With its reliability, safety, versatility and resource adequacy, photovoltaic energy has become one of the world’s most recognized renewable energy sources in the context of accelerating global consumption of fossil fuels such as coal and oil. Become the main pillar of the future global power supply. In the decade from 2005 to 2015, the annual compound growth rate of global PV installed capacity was about 42%. According to the prediction of the Joint Research Center of the European and American Commissions, by 2050, photovoltaic power generation will account for 25% of global power generation, to 2100. This ratio may increase to 64%.

Among the exports of all single crystal modules in the first three quarters of 2018, the total export volume was 300W, 345W and 340W, with exports of 1,241 MW, 1,072 MW and 955 MW respectively. The top five exporters of these three categories are as follows:

In the Middle East and Australia, Jinko Energy has received orders for parts for large power plants, supplying 340-345W single crystal components, enabling Jingke to become the export champion of 300/340 / 345W single crystal components in 2018, followed by Longji. In addition, due to the use of single crystal modules in large power stations in the Middle East and Australia, the market share of single crystals in these two markets in 2018 is higher than the global average. In the parts exported to the Middle East by China in June this year, the proportion of single crystals was as high as 66.6%.

Another market worthy of attention is Europe. The European market is entering a recovery phase. After the MIP ended on September 3, China’s monthly exports to Europe increased by 34%, mainly due to the increase in exports of monocrystalline silicon modules.

In addition, since the two major markets in Europe and the United States were affected by trade barriers in the past, many components were provided by overseas production capacity, and China’s component exports could not fully reflect the market’s single polycrystalline market. China’s wafer production capacity accounts for more than 97% of global production. Therefore, analyzing the export sales of Chinese silicon wafers can more accurately determine the proportion change of the single polysilicon market.

According to EnergyTrend, China’s wafer exports have declined slightly since 2018, but the proportion of monocrystalline silicon wafers has been on the rise since 2Q18, close to 50% and is expected to rise. The market share of the crystal market is about to stabilize, and the single crystal may reverse its market share by the end of 2020.