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China-built solar project makes World Cup greener

A packed audience cheers during the opening ceremony of the 2022 FIFA World Cup at the brightly lit Al Bayt Stadium in Doha, capital of Qatar, on Nov. 20. Since then, a photovoltaic plant built by a Chinese company has provided a steady stream of clean electricity, contributing to the global sporting event, providing an important green legacy.

The 800MW Al Kharsaah Photovoltaic Power Station is the first non-fossil fuel power station in Qatar, which was independently constructed by China Electric Power Guizhou Engineering Co., Ltd.

The power station, which was commissioned in mid-October, will significantly increase the share of renewable energy in the football match’s energy consumption mix and help Qatar meet its pledge to host a carbon-neutral World Cup, the company said.

Wei Yujin, deputy manager of the project, said: “The carbon emissions saved by this project will be used to offset about half of the emissions during the World Cup.” electricity demand.”

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War accelerates global renewable energy transition

Russia-Ukraine war, global renewable energy transition accelerates

The start of this round of Russia-Ukraine local war will have a positive impact on the acceleration of new energy alternatives to traditional energy sources. Throughout the day today, new energy stocks showed big gains. Zhongli Group, Sunshine Power, Trina Solar, Orient Sunrise, Foster, JinkoSolar, JA Tech, Longi, Goodway, Chint Electric, Zhonghuan, and Zhonglai all closed higher. The PV 50 ETF was up 1.53%.

Natural gas prices have skyrocketed recently. This is not good news for the European region where natural gas prices have risen nearly fourfold in the past year. Natural gas is now the source of one-third of the European region’s natural gas, and geopolitics is magnifying the supply problem again. As of 4 p.m. today, the Dutch TTF benchmark natural gas futures price rose for the fourth straight session, a one-day gain of 41 percent. U.S. President Joe Biden has also said that further punitive measures will be taken against Russia. Any sanctions that restrict Russia’s access to foreign currency would upend the commodity markets for oil, natural gas and metals, crops and other commodities.

Europe has a very high local gas dependency of 90%, so at this point in time when gas prices are soaring, more industrial, power and heating users accustomed to gas will be looking for safer ways to meet their needs, and the substitution of new energy sources such as solar will be accelerated.

Wood Mackenzie has pointed out that with the surge in variable power output, Europe has four options for balancing grid operations: pumped storage facilities, natural gas-fired peaker plants. Rory McCarthy, the agency’s principal analyst, said, “For modern power systems, natural gas-fired plants can achieve full power output in less than two minutes and can be more efficient when running partial load situations, capable of supplying power for an infinite duration of generation, which is predicated on an uninterrupted supply of natural gas.”

But by 2030, battery storage systems will surpass peak natural gas-fired power plants as the least expensive option for balancing the European grid.

 Installed capacity for energy storage projects in all sectors in Europe is expected to grow from 3GW today (excluding pumped storage facilities) to 26GW by 2030 and 89GW by 2040. mccarthy notes that by 2040, Europe could have 320GWh of energy storage capacity available for balancing the power system. Most of that will come from customer-side battery storage systems. “The cost of fuel and coal-fired generation will also rise, and net-zero emissions policies will ultimately target decarbonization of all electricity market services,” McCarthy said.

Analyst Bloomberg New Energy Finance has issued a survey that notes that the growing popularity of solar power facilities in the U.S. has eaten into the operating hours of natural gas-fired power plants, requiring them to restart and shut down more frequently, thus increasing their operating costs due to fuel demand and wear and tear.

Currently, when natural gas prices are too high, investors are making more prudent decisions about the need to switch to new generation methods to avoid the problem of this high priced raw material.

Of course, the exporters of natural gas do not want to see this situation continue. They will also try to find ways to keep gas prices more than ridiculously high, otherwise exporting gas will become difficult once a situation of abandonment of use on the industrial and power side develops.

Looking at the first phase of the Russia-Ukraine conflict in 2014 (January 19, 2014 to March 20, 2014), the performance of broad asset classes saw a significant upswing in commodity prices, as much as 7.6%. While crude oil prices rose by 4.2% and gold prices rose by 6.1% (from Haitong Securities.) The continued high price of crude oil will also bring renewed attention to the use of electric vehicles and clean cars.

In terms of the future development of new energy, especially the photovoltaic industry, this year will continue to improve.

23 February, the relevant parties predicted that the scale of new photovoltaic installations in 2022 may increase to more than 75GW, about 75-90GW. The value compared to the National Energy Board data – 2021 national PV new installations of about 55GW, an increase of 36%-64%. At the same time is expected to 2022-2025, China’s annual average new PV installation will reach 83-99GW. 2021, according to the Ministry of Industry and Information Technology data, China’s PV polysilicon, wafer, cell, module production reached 505,000 tons, 227GW, 198GW, 182GW, an increase of 27.5%, 40.6%, 46.9%, 46.1%. The annual export of PV products exceeded US$28.4 billion.

According to the latest research report of CITIC Capital, the domestic PV installation in January 2022 exceeded expectations, the national new PV installation of more than 7GW, an increase of 200% year-on-year. Among them, distributed PV new installed 4.5GW, up 250% year-on-year; centralized PV new installed 2.5GW, up 150% year-on-year. Upstream silicon, wafers, downstream batteries, modules, and inverters, auxiliary materials, all parts of the industry chain is generally full of orders, the start rate is not down but up. This year, the traditional off-season may not be “light”.

At this point, we expect the people of Ukraine to protect themselves and their families, to spend this special moment peacefully, and to return or find a peaceful home as soon as possible.

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Beijing Winter Olympics goes carbon neutral

It is also a solemn commitment made by Beijing when it joined hands with Zhangjiakou to bid for the 2022 Winter Olympics and Winter Paralympics. Low Carbon Management Report for the Winter Olympic Games (Pre-Games)” (hereinafter referred to as the “Report”). The Report systematically presents the work related to the carbon management of the Beijing Winter Olympic Games, focusing on the carbon neutral methodology of the Beijing Winter Olympic Games, greenhouse gas emission baseline, actual preparatory process emissions, the effectiveness of low carbon management measures, the construction of forestry carbon sink projects, and corporate sponsorship of certified carbon emission reductions. After comprehensive calculations, the carbon emissions generated by the Beijing 2022 Winter Olympics and Winter Paralympics will all be neutralized.

Beijing Winter Olympics carbon emissions to be fully neutralized

At the early stage of preparation and hosting, the baseline greenhouse gas emissions of the Beijing Winter Olympics will be about 1.637 million tons of carbon dioxide equivalent according to the relevant carbon footprint methodologies at home and abroad. According to the actual situation of preparing and holding the Beijing Winter Olympics under the epidemic, the current revised baseline emissions are about 1.306 million tons of carbon dioxide equivalent.On June 23, 2019, International Olympic Day, the “Beijing 2022 Winter Olympic Games and Winter Paralympic Games Low Carbon Management Work Program” was officially released to the public, proposing 4 low-carbon energy, low-carbon venues, low-carbon transportation, and the Beijing Winter Olympic Organizing Committee taking the lead in 18 measures in 4 aspects, such as low-carbon energy, low-carbon venues, low-carbon transportation, and the Beijing Winter Olympic Organizing Committee taking the lead, in order to minimize carbon emissions generated by the Beijing Winter Olympic Games. At the same time, carbon offsetting measures such as carbon sequestration in forestry, independent action by enterprises and carbon inclusion system have been proposed. Since the release of the Low Carbon Plan, the Beijing Winter Olympic Organizing Committee has been working closely with the Beijing and Hebei governments to promote the implementation of the measures and has achieved positive results

First, all the venues have achieved green power supply. The Zhangbei flexible DC power grid pilot demonstration project will be put into operation in 2020 to transmit renewable energy from Zhangjiakou area to Beijing in a safe and efficient manner, fully meeting the electricity demand of the Winter Olympic venues in Beijing and Zhangjiakou area. The establishment of cross-regional green power trading mechanism, through the green power trading platform, will achieve 100% use of green power in all venues at the time of the tournament.

Second, all venues will meet green building standards. All new indoor venues have reached the three-star green building standard, and existing indoor venues have reached the two-star green building standard through energy-saving renovation. The innovative organization has formulated the “Green Snow Sports Venue Evaluation Standard”, and all the new snow sports venues of the Beijing Winter Olympics meet the standard. At the same time, the Beijing Winter Olympics used carbon dioxide refrigerant with a global warming potential (GWP) of 1 and ozone depletion potential (ODP) of 0 in four ice venues, which is the first time this technology is used in the Winter Olympics.

Third, to build a low-carbon transportation system during the games. According to the principle of “using electricity in the plains and hydrogen in the mountains”, electric vehicles and hydrogen fuel cell vehicles were promoted in each competition area. At the same time, the “Traffic Resource Management System” was built to realize real-time monitoring and unified command of traffic operation during the Beijing Winter Olympic Games, which greatly improved traffic organization and operation efficiency during the event.

Fourth, the Beijing Winter Olympic Organizing Committee took the lead in demonstrating. The Beijing Winter Olympic Organizing Committee has moved into the Shougang Industrial Theme Park, comprehensively utilizing and transforming the waste factory buildings, making full use of photovoltaic power generation, solar lighting, rainwater collection and utilization technologies, and building a green and high-standard Shougang office area for the Winter Olympic Organizing Committee, which not only meets the office needs of the Winter Olympic Organizing Committee, but also plays a role in promoting the transformation and development of Shougang.

Fifth, the two governments donated forestry carbon sinks. The Beijing Municipal Government and Zhangjiakou Municipal Government completed 710,000 mu of new round of one million mu afforestation and greening project and 500,000 mu of Beijing-Hebei ecological water source protection forest construction project respectively, and commissioned professional institutions to complete the monitoring and certification of the corresponding carbon sinks, with certified carbon sinks of 530,000 tons of carbon dioxide equivalent and 570,000 tons of carbon dioxide equivalent respectively. The Beijing Municipal Government and the Hebei Provincial Government donated all the above carbon sinks to the Beijing Winter Olympic Organizing Committee free of charge.

Sixth, enterprises sponsored the certified carbon emission reductions. Three official partners of the Beijing Winter Olympic Games, including PetroChina, State Grid and Three Gorges Group, actively supported the carbon neutral work of the Beijing Winter Olympic Games by sponsoring 200,000 tons of carbon dioxide equivalent carbon sinks to the Beijing Winter Olympic Organizing Committee in the form of certified carbon emission reductions.

In short, through the joint efforts of all parties, all carbon emissions of the Beijing Winter Olympic Games will be neutralized, and the goal of “holding a carbon neutral Winter Olympic Games” will be achieved as scheduled.

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Silicon price drops to 180,000 yuan per ton

Earlier this year, several institutions gave the national new PV installation 75GW +, the global new PV installation 220GW + market expectations, an important basis is 2022, silicon supply (domestic production + overseas imports) is expected to reach 850,000 tons. According to Sobi PV net calculations, these silicon materials are expected to meet nearly 300GW module production. Especially in the fourth quarter, a single quarter supply of more than 300,000 tons, when silicon prices may appear more substantial decline.

But the first month of the year, the upstream price increase behavior apparently let everyone surprised. According to the China Nonferrous Metals Industry Association Silicon Branch statistics, over the past four weeks, prices of different grades of silicon have risen by nearly 10,000 yuan per ton. At the same time, just in January, Longi, Central two leading enterprises of silicon wafers were two rounds of price increases, the rate of increase far more than the cost of silicon material price increases. Among them, 166 wafer prices rose by a cumulative maximum of 8.16%, 182 wafers rose by a cumulative maximum of 12.28%, 210 wafers rose by a cumulative 11.04%.

A number of industry experts said that the reason for this situation is that the end of the domestic and foreign terminal demand, combined with the Spring Festival holiday some manufacturers to increase inventory, as shown by the battery, module enterprises to enhance the willingness to purchase, silicon wafer enterprises to take advantage of the opportunity to increase prices. “In fact, the silicon wafer link overcapacity is more serious than the battery, module, beyond the global terminal demand of about double. Silicon wafer prices are expected to be difficult to maintain at the current level for a long time, and price cuts are the general trend. It is recommended that the relevant enterprises in each segment reasonably control their inventories to ensure subsequent profit margins.”

Silicon material needs to be reduced to 180,000 yuan/ton to ensure market demand throughout the year

According to Sobi Consulting statistics, in December 2021, the top five silicon enterprises produced 41,400 tons in total, with a comprehensive capacity utilization rate of 112.6%. In terms of silicon wafers, the two head enterprises’ start-up rate returned to more than 50%, and the integrated enterprises’ start-up rate was relatively high. In December last year, domestic silicon wafer production was 17.85GW, down 8.6% YoY. According to the production ranking, Longi, JinkoSolar, Zhonghuan, Shangji and JA ranked in the top five, with a total production of 12.35GW, accounting for 69.19% and an integrated utilization rate of 67.81%. Although there is a view that the actual capacity utilization rate of Zhonghuan is higher than the above data, the overall view is that the high prices in the upstream of the industry chain have affected the terminal demand and counteracted the upstream.

It is revealed that a few days ago there have been a number of power investment enterprises began to readjust the layout of new energy projects in 2022, more choice of wind power to complete the renewable energy investment requirements. In this regard, a number of senior practitioners told Sobi PV network, behind this decision, there are local government “resources for industry” requirements under the helpless, there are land rent, tax costs (including subsequent taxation may) concerns, there are annual utilization hours, the number of hours of trading calculations, but also the cost of photovoltaic systems in 2022 can not be reduced to The expected level of concern. “According to the 6.5% annualized rate of return measurement, in a class I resource area, the overall cost of PV system with energy storage shall not exceed 4.5 yuan / W, the PV itself can not exceed the cost of 4 yuan / W, component purchase price is best controlled at 1.8 yuan / W or less.”

How about the actual purchase price? According to the PV price index released by Sobi Consulting before the Chinese New Year, the average price of monocrystalline 166 double-sided modules purchased by ground power station projects in January reached 1.84 yuan / W, 182, 210 double-sided modules reached 1.86 yuan / W and 1.88 yuan / W. At the same time, some analysts pointed out that, due to the domestic 2022 collection of bids from various enterprises have been launched, overseas, especially India, Europe and other The market appears stocking demand, February component transaction prices may have a small increase. “If the first half of the silicon price can not drop to 180,000 yuan / ton, the domestic H1 new installed capacity may not meet expectations, which means that the end demand are piled up to the second half of the year, is not conducive to a steady decline in prices.”

What to solve the problem, the only way to reduce prices. Only upstream to further release capacity, lower prices, in order to fully open the PV market demand, revitalize the entire industry chain, especially so that new production capacity has a place to use, to avoid a massive surplus. According to the above analysts predictions, the first half of this year, silicon prices down to 180,000 yuan / ton, in the case of unchanged profit distribution of the links, component prices can be lower than the current 0.13-0.15 yuan / W. Considering that the market share of large-size components in 2022 will have a further increase, which is conducive to reducing system costs and improve project revenue, which means that more PV projects can be the level of yield Meet the internal requirements of central and state-owned enterprises, and can be implemented on the ground. This means that more PV projects can meet the internal requirements of central and state-owned enterprises and can be implemented.

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New Energy PV: From grid-connected to off-grid

At  present, there are two typical applications of PV, grid-connected systems and off-grid systems. The grid-connected system depends on the grid, and uses the “self-generation, surplus power online” or “full online” mode of operation. The off-grid system does not depend on the grid, and relies on the “store and use” or “store and use” mode of operation. Off-grid systems are highly practical for households in areas without a grid or in areas with frequent power outages.

Since off-grid is a rigid demand, the profit is relatively high. Installers who do grid-connected, want to do off-grid projects, which requires a partial change in thinking, if you continue to use the idea of grid-connected to do off-grid, it is possible that the deal will not be concluded or meet the requirements of customers.

1 off-grid system can not be considered a return on investment

We invest our money in real estate, stocks, industry and other projects, we have to calculate how much money we can make every year and how many years we can pay back. Grid-connected power generation is subsidized by the state, and building a power station is an investment, so customers are most concerned about the return on investment. But when we buy a cell phone, computer, clothes and other necessities, we do not calculate how many years we can earn back the capital, and the same goes for off-grid systems. The idea of off-grid installation is likely to be cancelled by the customer. The reason why off-grid systems are not economically viable is that they cost much more than grid-connected systems.

2 off-grid system cost is high

Off-grid systems consist of PV arrays, solar controllers, inverters, battery packs, loads, and so on. Compared with the grid-connected system, more batteries, accounting for 30-40% of the cost of the power generation system, and the components are almost the same. And the battery life is not long, lead-acid batteries are generally in 3-5 years, lithium batteries are generally in 8-10 years, after which they need to be replaced.

Off-grid inverters are 1.5 to 3 times more expensive than grid-connected inverters. Off-grid inverters have a more complex structure than grid-connected inverters; grid-connected inverters generally have a two-stage structure of booster and inverter, while off-grid inverters generally have a four-stage structure, including controller, booster, inverter, and isolation, and cost about two times more than grid-connected inverters.

The overload capacity of off-grid inverters is more than 30% higher than grid-connected inverters. Grid-connected inverters are connected to modules at the front stage and to the grid at the output, which generally do not need overload capacity because few modules have output power greater than the rated power, while off-grid inverters are connected to loads at the output, and many loads are inductive loads, and the starting power is 3-5 times the rated power.

Off-grid inverter production is low, the current PV grid-connected market share of about 98%, off-grid market share of about 2%, shipments are very low, can not be automated production, raw materials and production costs are much higher.

3 off-grid system why with energy storage battery

In the PV off-grid system, energy storage batteries account for a large proportion of the cost and solar modules, but the life is much shorter than the components, the task of energy storage batteries is energy storage, to ensure that the system power stability, at night or rainy days to ensure that the load power. Off-grid systems must be equipped with energy storage batteries, this is why?

One is the PV power generation time and load power time is not necessarily synchronized, PV off-grid system, the input is the module for power generation, the output connected to the load. Photovoltaic are daytime power generation, there is sunlight to generate electricity, often at noon the highest power generation, but at noon, the demand for electricity is not high, many household off-grid power station at night, then the electricity sent out during the day how to do, to be stored up, this storage device is energy storage batteries. Wait for the peak of electricity consumption such as seven or eight o’clock at night, and then release the power.

Second, photovoltaic power generation and load power is not necessarily the same, photovoltaic power generation is affected by radiance, not very stable, and the load is not stable, like air conditioners, refrigerators, start power is very large, usually running power is less, if photovoltaic direct with load, it will cause system instability, the voltage is high and low. Energy storage battery is a power balancing device, when the PV power is greater than the load power, the controller sends the excess energy to the battery bank storage, when the electricity generated by the PV can not meet the needs of the load, the controller and the battery power to the load.

In addition to the above three points, the design of off-grid systems and grid-connected systems are also different, components, inverters, storage batteries are customized according to the needs of users, only after these changes in thinking, in order to do a good job off-grid systems.

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Low power generation: what have you done to the inverter?

Overseas customer feedback, said the inverter output is limited, can not be effective output. After in-depth communication, we understand that there are problems with their inverter and module configurations: the modules are over-matched too much, resulting in excessive working current some of the time, inverter current-limited operation, and some power-limited phenomena.

In fact, this situation also happens in China from time to time, and many owners have done a lot of things that are unpleasant without understanding the operation mechanism of the inverter.

(1) Make a "shield" for the inverter

Mistake: Previously, when I did research, I found that customers installed shields to protect the safety of the inverter, but this not only did not protect the machine, but also affected the heat dissipation of the machine. Especially in the hot summer, the installation of the shield will easily cause the surrounding working environment to be too hot, resulting in the overheating and derating of the inverter, which will limit the output power and affect the power generation revenue.

Correct: String inverters are all IP65 or above protection level, and do not need additional overall protection. Therefore, we only suggest two points here: first, when string inverters are installed, you can install some protective canopy on its upper part to avoid direct rainfall; in addition, when installing multiple string inverters, you should pay attention to the inverter spacing to ensure enough space for heat dissipation and follow the installation manual recommendations as much as possible.

(2) Configure too many components, thinking that the more they are equipped, the more electricity they generate

There is a saying in the north that “the spoon is big, but the bowl is accurate”, which means that the bowl is only so big, and it can’t hold more rice. In fact, the same is true for inverter module configuration. For example, the maximum output power of Shengnengjie SE-5kw inverter is 5.5KVA, even if 6kw of power is input on the input side, its output will not reach 6kw, but only 5.5kw at most, which means the output power is limited.

Considering the impact of system loss, we usually recommend different over-provisioning ratio in different areas. Because, if the inverter over allocation is too high, it will not only waste the system cost, but also make the inverter overload for a long time, resulting in lower service life.

(3) Use DC sink box for convergence

As we all know, centralized inverters will add a sink box on the DC side, mainly to connect the components of the square array in series and parallel, and add lightning protection, fuses, DC switches and other protection devices, and then unified to the DC cabinet side of the inverter.

For string inverter, the DC sink box is directly omitted, and the lightning protection and overcurrent protection units are placed inside the machine, which greatly reduces the workload of construction and maintenance. However, we also found that some users are still using the old thinking of centralized configuration.

Wrong: The number of DC terminals on the input side of the inverter directly determines how many power components can be configured. Some customers ignore the current limit conditions on the input side and parallel-connect the modules before connecting to the inverter, resulting in excessive input current and burned fuses, or even damaged terminals, which affects the power generation revenue.

Correct: The power on the input side of the inverter, i.e. the current limit, needs to be fully considered. Generally, the maximum input current of the module is around 9-10A, and the double-sided module is slightly larger, but only around 11-12A, while the DC input side current of the inverter is mostly around 12.5A, so extra attention is needed when configuring.

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How many kilowatts of electricity does a PV panel generate in a year?

The world is rich in solar energy resources. Apart from the macro events of the PV industry, let’s go back to the micro PV panels. If someone suddenly asks you how many kilowatt-hours of electricity a PV panel can generate in a year? Probably many people would be stunned, yes, how much is it? This brings us to two determinants of PV power generation.

Firstly, the power generated by the PV panel.

Secondly, the area where the PV panels are installed.

In the same area, the higher the power of the photovoltaic panels, the shorter the time it takes to generate 1 degree of electricity, and the higher the amount of electricity generated in a day.

Photovoltaic panels, there is sunlight to generate electricity. So, no electricity can be generated at night. Similarly, in windy, foggy, rainy or snowy weather, little electricity is generated. This means that photovoltaic power generation is closely related to the area of installation. Different resource areas with the same type of photovoltaic panels will produce different amounts of electricity. Some places have an inherent advantage due to the abundance of light.

To calculate an average, a PV panel can generate almost 400 kWh of electricity a year (theoretical value).

Why is this a theoretical value? This is because, in addition to the power generated by the PV panel and the area where it is installed (equivalent annual hours of use), PV power generation is also subject to external factors, such as the angle and orientation of the installation, the local climate, the material of the connection lines, and surface obstructions.

The installation of PV panels requires the angle and orientation of the installation in order for the panels to receive sufficient light to be of maximum use. If the installation is haphazard, people have an angle, you lie flat placed; people sit north facing south, you sit south facing north, and scientific deviation, but not affect the power generation!

Rainfall, snowfall, long time haze, dust storms and so on, even the sun can not see, and then the good photovoltaic panels can not generate electricity.

If you use poor quality cables and other lines, the electricity generated is secretly leaking out, and it is useless to generate more, and it is also easy to have accidents. This shows the importance of the material.

Photovoltaic panels should be cleaned from time to time. For example, if there are large trees or tall houses near the photovoltaic panels, the total light is not even a few hours, so how to fully generate electricity. This is the problem of siting. Or, the local sandy wind, only to install photovoltaic panels, but not carefully maintained, the panels are covered with dust, also can not fully generate electricity.

All of the above are factors that affect photovoltaic power generation, so in order to generate more power, you also need to take care of the maintenance oh ~


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Concepts and operating modes of photovoltaic energy storage systems

The concept of energy storage

What is energy storage?

Energy storage mainly refers to the storage of electrical energy. Energy storage is also a term used in petroleum reservoirs to represent the ability of a reservoir to store hydrocarbons. Energy storage itself is not an emerging technology, but from an industrial perspective it is just emerging and is in its infancy.

So far, China has not reached the level where energy storage is viewed as a separate industry and supported by policies similar to those of the United States and Japan, especially in the absence of a mechanism to pay for energy storage.

What is photovoltaic?

Photovoltaic (Photovoltaic): short for solar power system, is a new type of power generation system that uses the photovoltaic effect of solar cell semiconductor materials to directly convert solar radiation into electricity, with independent operation and grid-connected operation.

At the same time, solar photovoltaic power system classification, one is centralized, such as large northwest ground photovoltaic power generation system; one is distributed (to > 6MW as the boundary), such as industrial and commercial enterprises plant roof photovoltaic power generation system, residential roof photovoltaic power generation system.

What is a photovoltaic system?

Photovoltaic power generation system can be divided into grid-connected photovoltaic power generation system and stand-alone photovoltaic power generation system according to whether it is grid-connected or not. Grid-connected photovoltaic power generation system mainly refers to the photovoltaic system that is connected to the grid and receives grid dispatch, such as various centralized or distributed photovoltaic power plants. Stand-alone photovoltaic power generation system mainly refers to a variety of independent of the grid operation of photovoltaic power generation systems, such as solar street lights, rural household photovoltaic power supply, etc. collectively referred to as photovoltaic systems.

What is photovoltaic + energy storage?

The combination of photovoltaic and battery as an energy storage device is photovoltaic + energy storage.

The working mode of photovoltaic energy storage system

Photovoltaic power generation has the characteristics of high output level in the short period of time at noon, low output level in other periods and daytime output, no output at night, energy storage technology has the ability to achieve the spatial and temporal shifting characteristics of electricity, for photovoltaic power plants to configure energy storage room to transfer the midday output of photovoltaic to other periods, to reduce the power plant output spikes, reduce abandoned light.

In the working process of battery storage system, the principle of minimizing the number of times of charging and discharging of energy storage system is to extend the service life of energy storage system. During the peak hours of photovoltaic power generation, the battery storage system is controlled to be charged and the power output of the photovoltaic power plant is cut to the peak. After the peak hours of PV power generation, the battery storage system is controlled to discharge. The discharge control of the energy storage system can help smooth the volatility of PV power output and assist system peak regulation to maximize the role of energy storage. According to the different roles of energy storage discharge can be divided into three working modes of energy storage system, which are peak shaving, peak shaving + suppression and peak shaving + transfer style

Working mode one: peak shaving

During the peak hours of PV power plant, the battery storage system is charged with the application goal of peak shaving, and after the peak hours of PV power, and during the daytime hours of PV power, the battery storage system is amplified and discharged to the lower limit of the SOE range of the battery storage system, and then the storage system stops working to ensure that the working time of the storage system is within the power generation time of the PV power plant, which does not additionally increase the working time of the PV power plant. The working time of the power station is not increased, which reduces the impact on the working arrangement of the PV power station due to the configuration of the energy storage system.

Working mode two: peak shaving + smoothing

During the peak hours of PV power plants, the charging of battery storage system is controlled with the application goal of peak shaving. The power fluctuation of large-scale PV power plant can be divided into two categories, one is the slow change of PV power plant output, such as the periodic change of PV power plant output caused by day and night alternation; the other is the sudden change of PV power plant output, such as the sudden drop of PV power plant output caused by floating cloud shading. The first round of changes is large but slow; the second type of changes is unpredictable and sudden, and the power output is reduced from full power to less than 30% of the rated value in 1~2s when it is serious. After the peak period of PV power output, to smooth the process of day and night alternation, PV power plant power drop fluctuations as the goal of controlling the energy storage system discharge, discharge to the lower limit of the SOE working range of the battery storage system, if it has entered the night, PV power plant power reduced to 0, the SOE of the energy storage system is still greater than 0.2, control the energy storage system to the rated power constant power discharge to SOE will be to 0.2, and then control energy storage system to stop working.

Working mode three: peak shaving + transfer

In the peak hours of the PV power plant, the battery storage system is charged with the application goal of peak shaving. The peak hours of PV power plant are from 8:30 to 18:30, and the evening peak of the load occurs between 18:00 and 22:00, during which the PV power plant has basically no power, and the battery storage system can be discharged to assist the system in peak regulation by controlling the battery storage system. The system SOE working range lower limit value, then the energy storage system stop working.