• The difference between AC coupling and DC coupling of optical storage systems
    2023.Nov 10
    The difference between AC coupling and DC coupling of optical storage systems
    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...
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  • Is installing photovoltaics in rural areas harmful to human health?
    2023.Nov 02
    Is installing photovoltaics in rural areas harmful to human health?
    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.
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  • The difference between co-location and hybrid energy storage plant models
    2023.Sep 08
    The difference between co-location and hybrid energy storage plant models
    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.
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  • How do solar battery work?
    2023.Aug 31
    How do solar battery work?
    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, ...
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  • There are various types of photovoltaic power generation, how many do you know?
    2023.Aug 28
    There are various types of photovoltaic power generation, how many do you know?
    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.
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  • Why does the grid-connected inverter stop working when the power grid fails?
    2023.Aug 25
    Why does the grid-connected inverter stop working when the power grid fails?
    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...
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