The difference between AC coupling and DC coupling of optical storage systems introduction Energy storage technology refers to the process of storing energy through media or equipment and releasing it when needed; photovoltaic + energy storage combines solar photovoltaic power generation with energy storage technology to store the electric energy generated by the photovoltaic system so that it can be used when needed. Ensure stable power supply when needed. Currently, the system solutions for photovoltaic + energy storage on the market mainly include DC coupling and AC coupling. So what is the difference between these two solutions? The difference between DC coupling and AC coupling DC coupling means that energy storage cells and photovoltaic modules are connected to the DC side of the integrated photovoltaic and storage machine. The integrated photovoltaic and storage machine is directly connected to the photovoltaic modules, and the energy collection point is on the DC side. AC coupling means that the energy storage system and the photovoltaic system are connected on the AC side. , the energy storage system (battery, energy storage inverter) and the photovoltaic system (photovoltaic modules, photovoltaic inverter) work independently of each other, and the energy collection point is on the AC side. However, due to differences in circuit structures and electrical equipment between the two, there are also major differences in working principles, flexibility, efficiency, etc. 1 Differences in working principles DC coupling: In this solution, the photovoltaic inverter and the bidirectional converter are integrated into a photovoltaic-storage integrated machine, and are directly connected to photovoltaic modules, power grids, batteries, etc. to form a whole. When the photovoltaic system is running, the electricity generated can charge the battery through the photovoltaic storage integrated machine, supply power to the load, or be input into the power grid. AC coupling: This solution includes two parts: photovoltaic system and energy storage system. The photovoltaic system consists of photovoltaic arrays and photovoltaic inverters; the energy storage system consists of energy storage inverters and batteries. The two systems can operate independently without interfering with each other, or they can be separated from the power grid to form a microgrid system. When the photovoltaic system is running, the generated power can be used to power the load through the photovoltaic inverter or be input into the grid, or it can be used to charge the battery through the energy storage inverter. 2 flexibility difference DC coupling: In this solution, photovoltaic modules, photovoltaic storage integrated machines and batteries are in a serial state and are closely connected to each other. The addition and removal of equipment is complicated and the flexibility is average. It is mainly used in new photovoltaic markets, such as newly installed Photovoltaic storage sys...

Is installing photovoltaics in rural areas harmful to human health? "Is installing photovoltaics in rural areas harmful to the human body?" On September 20, some netizens asked on the platform: At present, some towns and villages in County A have promoted rural photovoltaic projects, and they need to sign a contract with the operator during installation. How do the relevant departments supervise this kind of photovoltaic project? In addition, if photovoltaic panels are installed on the roof of your home, will there be any radiation to the human body? In response, the Development and Reform Commission of County A gave a detailed reply on the same day. According to reports, in order to promote the healthy and orderly development of distributed photovoltaics and improve the management level of distributed photovoltaics, in July this year, Municipal Development and Reform Commission, Municipal Urban and Rural Development Bureau, Municipal Agriculture and Rural Affairs Bureau, Municipal Emergency Management Bureau, and Municipal Market Supervision and Administration Bureau , the Municipal Power Supply Company jointly issued the "Notice on Regulating Distributed Photovoltaic Management in City A (Trial)", clarifying construction requirements, implementing main responsibilities, strengthening local supervision, and proposing reasonable and orderly access, and increasing laws and regulations related to distributed photovoltaics and policy publicity efforts to jointly optimize the development environment for distributed photovoltaic projects and effectively safeguard the people’s right to know. People who are unfamiliar with photovoltaic construction and development contracts can check the "Household Photovoltaic Power Station Cooperative Development Contract (Template)" and "Household Photovoltaic Product Sales and Installation Contract (Template)" published on the website of the National Energy Administration. Photovoltaic power generation projects belong to the encouraged investment projects in the "Guidance Catalog for Industrial Structural Adjustment". “The photovoltaic modules themselves do not produce any electromagnetic radiation when generating electricity, but in order to convert the DC power generated by the photovoltaic modules into AC power and connect it to the power grid, a lot of power equipment and electronic devices are usually required, and these devices will affect the operation of the power grid. The surrounding electromagnetic environment." The staff said that after scientific measurement, the electromagnetic environment of the solar photovoltaic power generation system is lower than the limits of various indicators; in the industrial frequency band, the electromagnetic environment of the solar photovoltaic power station is even lower than the value generated by commonly used household appliances. It will have an impact on personal health.

The difference between co-location and hybrid energy storage plant models Co-location power station Modeled as an independent power station, energy storage facilities co-located with new energy power stations have independent metering arrangements, submit outage requests independently, receive dispatch instructions independently, and can be operated by different entities. CAISO has adopted several policy changes to help regulate co-located plants in participating markets. In 2021, CAISO implemented the Aggregate Capacity Constraint (ACC) function [2] [3] to ensure that dispatch orders to co-located power plants behind the utility grid connection point do not exceed the constraints of the utility grid connection point. ACC can also limit the battery's FM wins. CAISO has adopted rules allowing co-located energy storage plants to deviate from dispatch orders in certain circumstances in order to allow renewable energy plants at the same public grid connection point to generate electricity while meeting ACC limits. These changes will introduce optional features to prevent energy storage plants from receiving charging orders that exceed the dispatched operating targets of new energy plants at the same public grid connection point. The changes will also allow co-located storage plants to deviate from market charging orders to avoid charging from the grid when the actual output of renewable resources at the same public grid connection point is lower than predicted. hybrid power station Hybrid plants are modeled as single plants because they have a single bidding curve for all their components and receive unique dispatch instructions from CAISO. Hybrid plant operators self-optimize their resource components to meet dispatch directives.

Introduction On the Earth's surface, there's a lot of energy: about 173,000 terawatts. If we calculate how much energy is used by the entire population of the planet, this number increases by a factor of more than 10,000. In order to make full use of solar energy, let us see, how does a solar cell work? And how is this energy converted into electricity? How Solar battery Operate A solar battery is a system consisting of a large number of related photovoltaic cells. They are usually made of semiconductors, the most common of which is silicon. In a battery cell, crystalline silicon sits between two layers of different conductivities, with each atom connected by strong bonds to four adjacent layers. These links hold electrons and don't allow current to flow. So how a solar cell works: electrons transition from a layer with an excess of electrons (n-type) to a layer with defects (p-type), in this transition we call it a pn junction, one side forms a positive charge and the other negative charge on one side. Sunlight is a stream of tiny particles, namely: photons. The photons collide with the photocells, "kicking" the electrons from their junction, leaving a hole in their place. Due to the electric field effect of the p-n transition, the negatively charged electrons move towards the positively charged holes. Therefore, mobile electrons accumulate on the surface of the battery. They then flow along the external circuit to the opposite layer, performing electrical work at the same time. One such photocell has a power of 0.5 watts. Combining batteries into modules can increase the power of the battery, such as 12 batteries is enough to charge a mobile phone, of course, if you want to power the whole house, then you need many such modules. Solar cells can work for decades because the only moving elements in their design are electrons, and they keep coming back to where they came from, meaning nothing is wasted or worn out. (1) This decision will not only be influenced by politicians, but also by leading companies. In addition, there is also a physical problem: solar energy cannot be evenly distributed on the surface of the earth. This is much less the case on cloudy days or at night, for example. That means more effort is needed to produce more efficient batteries, as well as create the infrastructure to store the generated energy. (2) The effectiveness of the photovoltaic cell itself still raises many questions. If the sunlight is not absorbed but instead reflects off the surface of the cell, or if the electrons return to the holes before passing through the circuit, the photon's energy is lost. Currently, the most efficient cells have an efficiency of 46%, and most factories are less efficient - around 15-20%. At the current level of solar technology development, humans can still provide energy to the world. It's just a matter of financing, creating the necessary infrastructure, and finding enough space. According to preliminary calculations, ...

In photovoltaic power generation, there are many different types. This article will introduce some types and differences. Photovoltaic power plants are divided according to scale and function, and are mainly divided into two categories: centralized and distributed. The centralized photovoltaic power station is a power station specially used for power generation and sales, which occupies a large area and costs a lot. Specifically, it installs photovoltaic arrays in wide areas such as mountains, water surfaces, and deserts. The photovoltaic array generates direct current under sunlight, and then converts direct current into alternating current through an inverter, and connects it to the grid through a booster station. Centralized photovoltaic power plants are usually large in scale, generally above 10MW. A distributed photovoltaic power station refers to a power station that can sell the generated electricity and use it by itself, with a small footprint and low cost. Specifically, it is a photovoltaic power generation facility built near the user's site. The operation mode is mainly for the user's own use, and the excess electricity can be connected to the Internet. Distributed photovoltaic power generation facilities are characterized by construction according to local conditions, with the principles of clean and efficient, decentralized layout and nearby utilization, making full use of local solar energy resources, replacing and reducing the consumption of fossil energy. When distributed photovoltaic power plants are installed, they can also be distributed on the surface of buildings. Photovoltaic power plants combined with buildings can be divided into two types: BIPV and BAPV. BIPV refers to the fact that photovoltaic modules are highly integrated in the building as a part of the building. The photovoltaic module undertakes the function of some building materials. If the photovoltaic material is removed, the function of the building will be affected. BAPV refers to the addition of photovoltaic modules to buildings. The photovoltaic material itself does not undertake any function of the building. If the photovoltaic part is removed, the use of the building will not be affected. This is the mainstream type in the market. According to different business models, photovoltaic power plants can be divided into mountain light, ground light, fishing light, and agricultural light. Shanguang refers to the construction of photovoltaic power stations on mountainous land, Diguang refers to the construction of photovoltaic power stations on flat land such as the Northwest Gobi area, Yuguang refers to generating electricity while fish farming, and agricultural light refers to planting or grazing at the same time To generate electricity.

When installing a photovoltaic system, some people will hold the mentality of "even if the power grid fails, if there is sun, their home can still use electricity". The reality is that when the power grid fails, the photovoltaic system of their home will only be exposed to the sun , will also stop running, and will not use electricity. The reason for this phenomenon is the grid-connected inverter, which must be equipped with an anti-islanding device. When the grid voltage is zero, the inverter will stop working. The anti-islanding device is an essential device for all photovoltaic grid-connected inverters. The reason for this is mainly for the safety of the grid. When the grid is powered off, the maintenance personnel are ready to overhaul the circuit. Electricity can easily cause safety accidents. Therefore, the national standard stipulates that the photovoltaic grid-connected inverter must have the detection and control functions of the islanding effect. The detection methods of the islanding effect include passive detection and active detection. The passive detection method detects the amplitude of the voltage and current at the output of the grid-connected inverter. The inverter does not add interference signals to the grid, and detects the current phase offset and frequency Whether the parameter exceeds the specified value is used to judge whether the power grid is out of power; this method does not cause grid pollution, and there will be no energy loss; and active detection means that the grid-connected inverter actively and regularly applies some interference signals to the grid. Such as frequency shift and phase shift, since the power grid can be regarded as an infinite voltage source, these interference signals will be absorbed by the power grid when there is a power grid. If the voltage exceeds the standard, it can be judged whether the island effect has occurred. At present, the anti-islanding function technology of grid-connected inverters is fully mature. Therefore, in household grid-connected projects, there is no need to add anti-islanding devices. In some places, not only photovoltaic grid-connected inverters are connected to the grid, but also possible It is a distributed power source such as wind power generation, biomass power generation, and energy storage system. The State Grid Corporation of China stipulates that when the access capacity of the grid connected to the power grid exceeds 25% of the rated capacity of the distribution transformer in the station area, the main switch of the low-voltage side of the distribution transformer should be Transform it into a low-voltage main switch, and install an anti-islanding device at the low-voltage busbar of the distribution transformer; the low-voltage main switch should have an operation locking function with the anti-islanding device, and when there is communication between the busbars, the connection switch should also have an operation with the anti-islanding device Latching f...

Technical Analysis of Distributed Photovoltaic Power Generation System The distributed photovoltaic power generation system quotation provided by a professional distributed photovoltaic power generation system service provider generally includes: components, brackets, inverters, circuit breakers, DC boxes, AC boxes, fuses, DC cables, AC cables, Convergence terminal, grounding terminal, switch, labor, transportation, tax and other items, considering the size, design and construction difficulty of each project, the market purchase price fluctuates, and the quotation will also fluctuate accordingly; In North China, the Yangtze River Delta, and the Pearl River Delta, where the application of distributed photovoltaic power generation is relatively dense, the difference in solar plane radiation is not as large as that in the western region, generally no more than 20%. If the optimal power generation inclination is set, the overall system efficiency is above 80%. Generally speaking, the average annual power generation of a 1KW project for 25 years should be around 900~1300kwh; If it is an industrial and commercial factory roof with steel structure color steel tiles, generally only the south-facing side is covered with photovoltaic modules (the natural inclination angle of the standard factory roof is generally 5° to 10°), and the laying ratio is generally 1KW covering an area of 10㎡. That is, a 1MW (1MW=1000KW) project needs to use an area of 10,000 square meters; If it is a brick-and-tiled roof of a household villa, generally the unsheltered roof area will be covered with photovoltaic modules from 08:00 to 16:00. Although the installation method is slightly different from that of the color steel tile roof, the area ratio is similar. , also 1KW covers an area of about 10㎡. In other words, a villa roof with a relatively large area (100-150㎡) can probably be installed with a photovoltaic power generation system of about 10KW, and the average annual power generation in 25 years is about 9,000-13,000 kwh (specific parameters need Hangyu Solar to issue professional project proposals) It will be determined after the book, only the general concept is given here); If it is a flat concrete roof, in order to design the best fixed horizontal inclination, each row of modules needs to be spaced at a certain distance to ensure that they are not blocked by the shadow of the front row of modules, so the roof area occupied by the entire project will be larger than that of color steel that can be tiled. Tiles and villa roofs. Generally speaking, after considering complex factors such as natural shading and parapet height, the roof area occupied by 1KW is about 15-20㎡, that is, 1MW project needs to use an area of 15,000-20,000㎡. Based on this, you can estimate how much capacity you can install on your roof and roughly how much electricity you can generate.

The low power generation can be checked from the following aspects: 1. Locate the problem. Check the system through the daily power generation and monitoring software to determine whether the inverter is not working, or the strings are burned, missed, or the strings are generating electricity normally? Are the operating voltages of the strings similar, whether there is current, and whether there are strings with low current? 2. Surrounding environment On-site inspection of the building parapet height of the photovoltaic power station, floor coverings (lightning rods, exhaust and dust discharge channels, etc.), surrounding coverings (tall buildings, trees, etc.), will they form a block sooner or later? Are there any corrosive factories around, such as ironworks, chemical plants, etc. Is the dust and powder layer on the components serious? Whether the lower edge of the module is covered by water stains and dust. Whether the module is ventilated. The power generation of the module installed in the unventilated greenhouse is lower than 10%! Whether the inverter is installed under direct sunlight, overheating will cause the inverter to derate. Is the cooling system (fan) of the inverter working normally? 3. System & power grid problem Are the component models, power, and number of blocks of each string of each MPPT consistent? Are the components of the same string facing the same direction? Is the number of module blocks in the string too small, and is the operating voltage of the string too low? (Single-camera is recommended to be greater than 420V, three-camera is greater than 630V) Is there too much over-provisioning of components, and does the inverter have power peak-shaving operation when the light is good? Is the power grid connected to it stable? Is there intermittent grid voltage that is too high and causes the inverter to shut down?

Development Trend Analysis of Photovoltaic Film Industry Adhesive film is a thin film material with good flexibility and adhesion. Photovoltaic adhesive film is applied to solar panels to protect the panels and improve the photoelectric conversion efficiency of the panels. The emergence of the photovoltaic adhesive film market is mainly to solve the problems existing in traditional solar panels, such as being easily affected by the external environment and reducing efficiency due to scratches and other factors. Development Status of Photovoltaic Film Industry With the promotion of global new energy policies, the photovoltaic market has developed rapidly, and the application of solar panels has become more and more extensive. Among them, as an important part of solar panels, photovoltaic adhesive film has continuously expanded its market share. According to statistics, the global photovoltaic adhesive film market reached US$3.12 billion in 2018, and is expected to reach US$5.5 billion by 2025. As the world's largest solar panel manufacturer, China's photovoltaic film market share is also increasing, and currently accounts for more than 60% of the global share. Development Trend of Photovoltaic Film Industry 1. Environmental protection With the improvement of global environmental awareness, various industries are actively exploring more environmentally friendly materials. The environmental pollution caused by the production materials and processing technology of photovoltaic film has become the focus of the industry. In the future, the photovoltaic adhesive film industry will introduce more environmentally friendly production solutions, including material selection and process improvement. 2. Enhanced Innovation How to enhance the function of photovoltaic adhesive film to improve the efficiency of solar panels is a major problem in the industry. In addition to the continuous improvement of materials, companies in the industry have begun to explore more innovative enhancement solutions, such as adding new materials, developing new coating technologies, and improving the transparency of adhesive films. These innovative enhancements will promote the continuous development of the industry. progress. 3. Expansion of application fields At present, photovoltaic adhesive film is mainly used in the field of solar panels, but in the future, with the continuous innovation of technology and people's emphasis on renewable energy, the application range of photovoltaic adhesive film will continue to expand. At present, enterprises have applied photovoltaic film to architectural glass, aviation and other fields through technological innovation. In the future, there will be more application scenarios waiting for the development of the industry. epilogue As an important part of solar panels, the photovoltaic film industry has broad prospects for development. In the future, the photovoltaic adhesive film industry will continue to improve environmental protection and ...

Why do lithium batteries need battery balancing? In today's context of increasing awareness of environmental protection, lithium batteries, as an efficient and reliable energy storage device, are gradually becoming the mainstream choice. However, lithium batteries may have problems such as capacity mismatch and excessive voltage difference during long-term use, which requires the application of battery balancing technology. This article will explore why lithium batteries need cell balancing, and explain its importance and how to achieve it. Lithium batteries pass through battery balancing, and each unit in the battery pack can be effectively monitored and maintained in a healthy state of charge (State of Charge, SoC). This not only increases the number of battery cycles, but also provides additional protection against damage to the battery cells due to overcharging/deep discharging. Active and passive equalization Passive equalization consumes excess charge through bleeder resistors, so that all battery cells have approximately the same SoC, but it does not prolong the running time of the system. Usually, the equalization that uses resistors to dissipate energy is called passive equalization. Active balancing is a more sophisticated balancing technique that increases system runtime by increasing the total charge available in the pack as charge is redistributed within the cells during charge and discharge cycles. Compared with passive equalization, active equalization can shorten the charging time and reduce the heat generated during equalization. Usually, the equalization achieved through capacity transfer is called active equalization. Active Cell Balanced Discharge As shown in the figure below, it is a typical battery pack at full capacity. Full capacity means that the charge capacity reaches 90%, because keeping the battery at (or close to) 100% capacity for a long time will reduce its service life soon. And full discharge refers to discharge to 30%, which prevents the battery from entering a deep discharge state. Over time, the characteristics of some batteries become worse than others. Even if some battery cells still have a lot of capacity left, weak battery cells limit the system run time, 5% of the battery capacity mismatch will cause 5% of the energy to be ineffective. For large-capacity batteries, it means that a lot of energy is wasted. This situation is particularly critical for remote systems and systems that are not easy to maintain. Unused energy also leads to increased battery charge and discharge cycles, reduced battery life, and higher costs due to frequent battery replacement. With active balancing, charge is redistributed from strong cells to weak cells, completely draining the battery pack of energy. Active Cell Balanced Charging If the pack is charged without equalization, the weak cells will reach full capacity before the strong cells, again becoming the limiting factor; at this point, they limit the total energy that can b...