What are the uses of three types of photovoltaic inverters: grid connected, off grid, and microgrid

Grid-connected: PV modules pass through a grid-connected inverter.

The power generation is uploaded to the national grid.

For self-use, the surplus electricity is connected to the national grid.

Off-grid: The PV module charges the battery through the charge controller and the load through the inverter.

Use. The electricity from photovoltaics is used first, and the surplus electricity is stored, and the electricity cannot be connected to the national grid.

Microgrid energy storage: It is built by a variety of energy sources, such as photovoltaic power generation, wind power generation, diesel engine power generation, and hydroelectric power generation, and these electricity are managed through the EMS energy management system with optimal configuration.

For self-use, energy storage with batteries, and surplus electricity is connected to the national grid. There are also household grades.

Three types of inverters are used in different situations:

Grid connection: There is a mains access point, and the mains power is available at ordinary times, and when the module cannot generate electricity on rainy days, it will not affect the user's use.

Off-grid: The purpose is to use photovoltaic power generation for their own use, and store excess electricity for use at night or on rainy days, without being affected by mains power outages. It is more widely used in areas without electricity.

Microgrid energy storage: It is generally used in large non-electric areas, such as towns and villages, and large public places such as islands. Generally, energy storage inverters are also installed at the residential level, which may be a little more costly.

In short, according to your own application conditions, you can choose the photovoltaic system that suits you, and you can get the optimal configuration in terms of application and cost.

All kinds are different, connected to the grid, off-grid and not connected to the grid.

Here's how it works:1Photovoltaic panels:

Photovoltaic panels convert solar energy into direct current. When sunlight hits a photovoltaic panel, the photons excite the semiconductor material inside the photovoltaic cell, generating an electric current. 2.

MPPT (Maximum Power Point Tracking): The PV inverter is equipped with an MPPT controller inside, whose role is to track the maximum power point output of the PV panel to ensure that the system can get the maximum power output. 3.

Inverter: The inverter is the core component of the photovoltaic power generation system. It converts direct current into alternating current, bringing it into line with the voltage and frequency requirements of the public grid.

The inverter contains electronic components, such as transistors and switches, which convert current by controlling the state of the switches. 4.Public Grid Connection:

The inverter connects the converted alternating current to the public grid via a grid connection device such as a grid interface. In this way, the electricity generated by the photovoltaic power generation nuclear hail sales system can be injected into the public grid for use by other users. Through the above working principle, the single-phase grid-connected photovoltaic inverter realizes the efficient conversion and power sharing of the solar photovoltaic power generation system, integrates renewable energy into the existing power network, and realizes sustainable development and clean energy utilization.

Summary. Hello, in a single-phase grid-connected PV inverter, there are three main components: DC input, converter and AC output.

Here's how it works: The DC generated by the PV panels is fed into the DC port of a single-phase grid-tied PV inverter, and an intermediate capacitor helps to adjust the current and the amplitude of each peak. Among them, the control circuit will clamp the DC voltage to ensure its stability within a certain range.

Subsequently, the direct current passes through the converter through the circuit, converts the direct current into 220V, 50Hz alternating current, and then sends it to the mains power network. At the same time, if the energy output of the power generation system is greater than the difference between the current load and the power direction, the excess power can be reversed into the municipal power supply system, and vice versa, it will be absorbed. This approach allows the mains network to introduce more clean energy and reduce dependence on traditional fossil fuels.

Hello, in the single-phase grid-connected photovoltaic inverter, there are three main components: DC input, converter and traffic sail megacurrent output. Here's how it works:

The DC generated by the PV panels is fed to the DC port of the single-phase PV inverter, and an intermediate capacitor helps to adjust the current and the amplitude of each peak. Among them, the control circuit will clamp the DC voltage to ensure its stability within a certain range. Subsequently, the direct current passes through the converter through the circuit, converts the direct current into 220V, 50Hz alternating current, and then sends it to the mains power network.

At the same time, if the energy output of the power generation system is greater than the difference between the current load and the power direction, the excess power can be reversed into the municipal power supply system, and vice versa, it will be absorbed. This approach allows the mains network to introduce more clean energy and reduce dependence on traditional fossil fuels.

In addition, single-phase grid-connected PV inverters also need to have a variety of protection measures, such as short-circuit protection, over-temperature protection, overload protection, over-voltage protection, under-voltage protection, etc. These protective measures can ensure the operational safety and stability of the anti-hand hand change system. In the specific operation process, the system will default to the monitoring bucket cluster to detect the grid voltage, grid frequency, current and other related parameters, if these parameters are abnormal, such as the grid voltage changes greatly, the inverter will actively switch the operation and stop injecting energy into the mains network.

This protection helps prevent potential transmission problems and protects the safety and stability of the grid system.

The function of the photovoltaic grid-connected inverter: in fact, the simplest is the role of boosting, which converts direct current into alternating current (220V). (Inverter manufacturer:Easter

At present, the more common solar inverter methods in the world are: centralized inverter, string inverter, multi-string inverter and module inverter.

Grid-connected inverters are generally used in the system of large-scale photovoltaic power stations, many parallel photovoltaic strings are connected to the DC input of the same centralized inverter, generally the use of three-phase IGBT power modules for large power, the use of field-effect transistors for small power, and the use of DSP conversion controller to improve the quality of the generated power, so that it is very close to the sine wave current.

The input voltage is raised or lowered by the DC DC conversion, and its output is regulated for maximum efficiency. After some additional voltage buffering, the DC voltage is converted to AC voltage by a switching frequency of 18 20kHz in the left bridge. In general, a single-phase H-bridge is a common configuration at the DC AC level, however, three-phase and other configurations can also be employed.

Finally, a sinusoidal alternating current output for grid-connected photovoltaic power generation systems is generated by a low-pass filter.

The main circuit of the inverter needs to be realized by the control circuit, generally there are two control modes of square wave and sine wave, and the inverter power supply circuit of square wave output is simple, low cost, but low efficiency and large harmonic component. Sine wave output is the development trend of inverters, with the development of microelectronics technology, microprocessors with PWM function have also come out, so the inverter technology of sine wave output has matured.

The inverter with a square wave output.

1.The inverter with square wave output mostly uses pulse-width modulation integrated circuits, such as SG3525, TL494, etc. Practice has proved that the use of SG3525 integrated circuit, and the use of power MOSFET as a switching power element, can achieve the highest performance of the inverter, because SG3525 has the ability to directly drive the power MOSFET and has an internal reference and operational amplifier and under-voltage protection function, so its peripheral circuit is very simple.

An inverter with a sine wave output.

2.The inverter of sine wave output controls the integrated circuit, and the inverter of sine wave output can be controlled by microprocessor, such as 80C196MC produced by Intel, MP16 produced by Motorola and PIC16C73 produced by Mi Crochip, etc., these single-chip microcomputers have multi-channel PWM generators, and can set the dead time between the upper and lower bridge arms, and use Intel 80C196MC to realize the sine wave output circuit, The 80C196MC completes the generation of the sine wave signal and detects the AC output voltage to achieve voltage stabilization. The output end of the circuit generally uses LC circuit to filter out high-frequency waves to obtain pure sine waves.

Direct current control, indirect current control, power control.

PQ control, VF control, and sag control.

The inverter converts the direct current into alternating current, and if the DC voltage is low, it is boosted by the AC transformer, that is, the standard AC voltage and frequency are obtained. For large-capacity inverters, due to the high DC bus voltage, the AC output generally does not need a transformer boost to reach 220V, and in medium and small capacity inverters, due to the low DC voltage, such as 12V, 24V, it is necessary to design a boost circuit.

Medium and small capacity inverters generally have three kinds of push-pull inverter circuits, full-bridge inverter circuits and high-frequency step-up inverter circuits, push-pull circuits, connect the neutral plug of the step-up transformer to the positive power supply, two power tubes work alternately, and the output gets alternating current, because the power transistors are connected to the ground side, the drive and control circuit is simple, and because the transformer has a certain leakage inductance, the short-circuit current can be limited, so as to improve the reliability of the circuit. The disadvantage is that the utilization rate of the transformer is low, and the ability to drive inductive loads is poor.

The full-bridge inverter circuit overcomes the shortcomings of the push-pull circuit, and the power transistor adjusts the output pulse width, and the effective value of the output AC voltage changes accordingly. Since the circuit has a freewheeling loop, the output voltage waveform is not distorted even for inductive loads. The disadvantage of this circuit is that the power transistors of the upper and lower side arms are not in common ground, so it is necessary to use a dedicated drive circuit or an isolated power supply.

In addition, in order to prevent the joint conduction of the upper and lower bridge arms, the circuit must be designed to be turned off first and then turned on, that is, the dead time must be set, and the circuit structure is more complex.

The premise of improving conversion efficiency is to reduce losses. The loss of IGBT is the fundamental factor that determines whether the conversion efficiency can be improved, so the efficiency can be improved by reducing the loss of IGBT. However, it should be noted that there is a certain limit to the reduction of this loss, and it cannot be reduced indefinitely.

Moderately reducing the switching frequency is the key to improving the conversion efficiency, so as to avoid blindly reducing the switching frequency and causing the power quality to deteriorate.

Secondly, the conversion rate of the PV grid-connected inverter needs to reduce the loss of the transformer. The loss of the transformer is usually the first of its own copper and iron loss, which can reduce the loss of these two aspects, which can effectively improve the conversion rate of the inverter.

In addition, the loss of the reactor is also a key factor affecting the conversion rate. On the basis of this factor, the inductive reactance of the reactor can be reduced, and the conversion efficiency of the inverter can be effectively improved.

For details, you can consult Growatt, they are professional photovoltaic inverter manufacturers, and can give more professional and comprehensive answers.

1、igbt。It can reduce the loss of IGBT and reduce the switching frequency of IGBT, but it cannot be reduced indefinitely, because when the switching frequency is reduced, the waveform of the inverter will become worse, the power quality will be reduced, and the noise of the machine will be increased, so the switching frequency of IGBT can only be appropriately reduced.

2. The loss of the transformer. The transformer's losses are only its own copper and iron losses, and when these two losses are reduced, the conversion efficiency of the inverter will be improved.

3. The loss of the reactor. Increasing the q value of the reactor means reducing the inductive reactance of the reactor.

There are many ways to improve the conversion efficiency of inverters, and you can consult professional companies or relevant experts for detailed understanding.