When we are going to buy inverters, you will realize that there are many types of inverters. There are also different types of inverters through different classifications. According to the solar system it can be categorized as off-grid inverter, grid-connected inverter and hybrid inverter. If according to the connection of solar panels it can be classified as string inverter, centralized inverter, micro inverter. In this article, we will compare different inverters for you from these two classifications.
Where to use: Off-grid inverters are mainly used in areas far from the grid, they are also suitable for small to medium sized travel or caravan use. These places cannot be connected to the grid, but need some power support. For hybrid inverters, they are better suited for places where temporary power outages often occur, such as commercial buildings, industrial power use, etc. Apart from that, hybrid grid inverters are also more common in homes.
Cost: The cost of a hybrid inverter is significantly higher than the cost of an off-grid inverter. The hybrid inverter has the functions of both off-grid and grid-tied inverters, which means that the control module of the hybrid inverter needs to be more compact, and the technology required is more high-end, and the use of these processes and technologies will increase the cost of the hybrid inverter. For off-grid inverters, the process and technology used are not as good as that of mixed-grid inverters, so the cost of off-grid inverters is cheaper.
How it works: Off-grid inverters provide the electricity generated by the solar panels to the loads first, when the loads’ power needs are met, the excess electricity will be stored in the battery bank, but when the battery bank is full, the excess electricity generated by the solar panels can’t be utilized. When the solar panels fail to generate electricity, the electricity from the battery bank is then provided to the load for use. The hybrid inverter is connected to the battery as well as to the grid. When the battery bank is full, the excess power is delivered to the grid. When the solar panels are not generating power, the solar batteries will first supply power to the loads, and when the batteries are dead, the grid will supply power to the loads.
System Complexity: For off-grid inverters, they don’t need to process the power and deliver it to the grid. So this hardware will be easier to install. For hybrid inverters when they can handle grid-connected operation, they can also allow off-grid operation, which usually allows the power to be sold to the grid and stored in batteries, this kind of inverter requires more complex management systems and technologies.
Operation efficiency: In string inverter system, a string inverter has to control one or more solar panel strings to realize the tracking of solar panels, but in such solar panel strings, if one solar panel has poor power generation efficiency, it will affect the power generation efficiency of the whole string of solar panels. In the microinverter system, each solar panel is controlled by a separate inverter, and the power generation efficiency of the solar panels does not affect each other, which reduces the impact of the short board effect.
Installation location: For string inverters, they are generally installed under a string, usually using a fixed bracket to fix it on the column or on the adjacent wall, while the size and weight of the micro inverter itself will be relatively small, you can directly install the micro inverter on the PV mounting bracket, which basically will not take up the installation space of the solar panels.
Working Principle: String inverter is to invert the solar panels with a small inverter in each string, and finally the power from multiple small inverters will be gathered into a large inverter, and then input into the place where it is needed. For centralized inverter, it is to gather all the solar panels’ power together and use one large inverter to invert, and then finally deliver to the place where it is needed.
Efficiency: For string inverter, there will be potential difference between different strings and solar panels, which will cause more current loss, so the efficiency of this kind of string inverter is lower. As for the centralized inverter, under the larger input of the solar panel strings, it directly converts the DC power of the whole solar system, and in this process, the current loss is less, so relatively speaking, the centralized inverter has a higher working efficiency.
Function: Hybrid inverter is a combination of off-grid inverter and grid-connected inverter, which can realize the conversion of solar panels from off-grid mode to grid-connected mode. It can store the electricity generated by the solar panels in the batteries and can also deliver the electricity generated by the solar panels to the grid. However, ordinary inverters are not equipped with this bi-directional current function and reserve function of hybrid inverters, which can only convert DC power into AC power.
Usage: Hybrid inverters are usually used in photovoltaic systems to convert DC power generated by solar panels into AC power. However, for ordinary inverters, they cannot be used in photovoltaic system, they are usually used in vehicle, wind power system, hydro power system.
Working principle: Off-grid inverters are mainly used in connection with solar battery, so that the system installed with off-grid inverters can realize self-sufficient power supply, which is completely independent of the power grid. The grid-connected inverter has to be connected to the grid, and then the electricity generated by the solar panels is directly transmitted to the grid to realize the interconnection of power resources.
Power management: Off-grid inverters need to support the autonomous operation and battery control of off-grid solar systems to ensure sufficient energy supply. Off-grid inverters can still function even when the grid fails. They will also usually have a battery management system and battery charging controls in order to ensure that the solar battery are working properly.
Grid-connected inverters are primarily designed to follow the standards associated with grid delivery, and generally need to deliver power at a frequency and at a voltage that is consistent with that of the grid. When the grid power failure, the grid-connected inverter will automatically cut off the power so that it can ensure the safety of maintenance personnel. In addition, the grid-tied inverter also has intelligent grid monitoring and feedback functions in order to ensure the safety of the power grid.
Expandability: If you want to expand your off-grid solar system, you will need to increase the capacity of your solar panels in addition to the basic solar panels in order to store more power. You may also need to add more sophisticated control systems and battery management systems in the process. This requires careful planning and design of your solar system. In a system with a grid-tie inverter, you can expand your solar system by simply adding solar panels and a corresponding grid-tie inverter.
Complexity of the system: In a system with an off-grid inverter, you also need to install a system regarding the solar panels, which need to manage the power. Timely charging as well as supplying power to the load requires you to install additional battery monitoring and control systems to keep the batteries working, the complexity of such a system is higher, but in systems with grid-tied inverters they require fewer solar modules and no battery banks, so naturally the additional systems for the battery banks don’t need to be installed. In such systems, you only need the solar panels, the grid-tie inverter and the other components, and your system is subsequently simpler.
There are many ways to categorize inverters, but these two categories are the most common. By understanding the differences between these different inverters, you will be able to choose the one that is more suitable for you.
