What Is A Solar Inverter And How Does It Work?

A solar inverter is a device that converts direct current (DC) generated by solar panels into alternating current (AC) for use in home or commercial power grids. Its main function is to convert solar energy into electricity that can be used and stored, so that electronic devices can run on solar energy.

In a solar energy system, the inverter plays the role of a "gateway", converting solar energy into electricity that can be used and ensuring the stable operation of the system. It is not only responsible for current conversion, but also for monitoring and controlling the entire photovoltaic system to ensure maximum performance, record operating data, automatically disconnect from the grid (if applicable), interrupt grid power supply, protect the grid from overload, and quickly switch to backup power when the main power fails to ensure uninterrupted power supply.

How Does Solar Inverter Work?

The working principle of solar inverter mainly includes the following steps:

DC Conversion: Solar panels generate direct current (DC) when exposed to sunlight. This DC is transmitted to the inverter through cables.

Inverter Process: The inverter converts DC into alternating current (AC) through electronic switching devices (such as transistors or IGBTs). This process is usually achieved by quickly switching the direction of the current using pulse width modulation (PWM) technology.

Synchronize with the Grid: In a grid-connected system, the AC power generated by the inverter needs to be synchronized with the voltage and frequency of the grid to ensure safe power supply or feedback to the grid.

Maximum Power Point Tracking (MPPT): Modern inverters usually have MPPT functions to optimize the energy output of solar panels by adjusting voltage and current to ensure maximum power can be obtained under different lighting conditions.

Monitoring and Protection: The inverter is also responsible for monitoring the operating status of the system, including parameters such as voltage, current, power, etc., and providing necessary protection measures such as overload protection and short-circuit protection.

Output AC Power: Ultimately, the inverter outputs the converted AC power to the home electrical system or grid for use by household appliances or feedback to the grid.

Solar inverter is a key device that converts the DC power generated by solar panels into AC power for use in homes or businesses. It also has functions such as power regulation, voltage regulation and monitoring to ensure efficient operation and safety of the system.

Different Types of Solar Inverters

Solar inverters can generally be classified according to their use environment and working principle, power, waveform and other characteristics.

Classification by Operational Context and Functionality Concerning the Electricity Grid

On-Grid Solar Inverters

Grid-connected solar inverters, also known as grid-tied or grid-interactive inverters, are designed to work with the public grid. These inverters convert the direct current (DC) generated by solar panels into alternating current (AC), which can be used directly for home or commercial purposes, or fed back into the grid. String Inverters, Central Inverters, Microinverters all belong to On-Grid solar Inverters.

The main features of grid-connected inverters are the ability to feed excess power back into the grid, saving electricity bills through net metering, and relying on grid power supply, automatically disconnecting when the grid is disconnected for safety.

Off-Grid Solar Inverters

Off-grid solar inverters are used for stand-alone solar systems that are not connected to the public grid. These inverters are usually used in remote areas or where the grid is unreliable, and they convert the DC generated by solar panels into AC and store it in batteries for emergency use.

The main advantage of off-grid inverters is that they are completely independent of the grid and can provide power supply even when the grid fails, but they usually need to be equipped with a battery system to store energy.

Hybrid Solar Inverters

Hybrid solar inverters combine the characteristics of grid-connected and off-grid inverters and are able to switch between grid-connected mode and off-grid mode. In grid-connected mode, hybrid inverters can feed excess solar power back to the grid; in off-grid mode, it can draw power from the battery for home or industrial use.

The advantage of hybrid inverters is that they provide greater flexibility and reliability, especially in areas with unstable grids or frequent power outages. In addition, they can switch to backup power mode when needed to ensure that power is still available during power outages.

Classification by Waveform

Pure Sine Wave Solar Inverter

Pure sine wave solar inverters produce high-quality AC voltage waveforms with very low total harmonic distortion (THD), close to the quality of traditional grid power supply. They are suitable for all types of electrical loads, including sensitive electronic equipment and appliances. Because their output waveform is similar to the power provided by the grid, they are very useful in systems that need to feed power back to the grid.

Square Wave Solar Inverter

Square wave solar inverters are the simplest and cheapest type of inverter, but their output power quality is low and contains a lot of harmonics. This inverter is often used in small stand-alone photovoltaic systems to drive simple loads such as lighting and hand tools. However, due to the low quality of its output waveform, it is not suitable for most household appliances and sensitive equipment. Due to its limitations, square wave inverters have become largely obsolete and are rarely used today.

Classification by Power

Small power solar inverter

Power range: usually between 100W and 1000W.

Application scenario: suitable for small photovoltaic systems such as homes, offices and outdoor activities, and can power small appliances such as TVs, computers, printers, etc.

Features: small size, cheap price, simple installation, but relatively low efficiency.

Medium power solar inverter

Power range: generally between 1000W and 10kW.

Application scenario: suitable for medium-sized photovoltaic systems, such as some small commercial projects or larger-scale home systems.

Features: more efficient than small power inverters, suitable for occasions requiring higher output power.

High-power solar inverter

Power range: usually more than 10kW, and can even reach tens or even hundreds of kilowatts.

Application scenarios: suitable for large-scale industrial and commercial photovoltaic systems, such as large ground power stations.

Features: With higher stability and reliability, suitable for large-scale photovoltaic power generation projects.