What is a photovoltaic inverter? How does it work and how to choose the best one for your installation?
The efficient, ecological and economical operation of a photovoltaic installation mainly depends on the correct functioning of its key components. These can include the inverter, which is responsible for converting the direct current generated by the photovoltaic panels into alternating current found in the sockets of our house. Importantly, a photovoltaic system could not work without an inverter, which is so important for the modules. So, how does exactly an inverter work and which is the best one to be chosen?
What is an inverter?
A solar inverter is a type of power converter that converts the direct current produced by photovoltaic panels into alternating current found in household sockets. This is its basic function, from which, incidentally, its name derives - it regularly reverses the direction of the current flow. This alternating current flows once in one direction and once in the other.
But how do we know if an inverter is working well? First of all, from information about its efficiency, which is expressed as a percentage. However, when reading the parameters of an inverter, we should not consider its maximum efficiency, as this tells us how the inverter will perform under the best possible conditions, which practically never exist.
Operating concept of the solar inverter
The inverter performs the function of converting the DC current generated by the photovoltaic panels into AC current, the parameters of which enable the electrical appliances in the house to be powered.
The second important role that the inverter fulfills is to actively control and monitor the operation of the PV system. Thanks to the inverter, it is possible to quickly detect faults and optimize the operation of the PV system through the maximum power point tracking system, or MPPT. The main functions of the inverter therefore include:
- Converting direct current (DC) into alternating current (AC), which is found in our sockets (230V / 50H).
- Synchronizing the PV installation with the electricity grid.
- Recording of operating data.
- Monitoring of the entire photovoltaic system.
- Tracking the MMPT, or maximum power point of the photovoltaic modules.
- Fault diagnostics.
What are the different types of inverters?
There are three main types of inverter on the market. These include:
- On-grid inverter. This is an on-grid inverter. As the name suggests, it establishes a connection with the grid, giving back to the grid the surplus current accumulated. It also automatically adjusts the voltage to the grid level.
- Off-grid inverter. This is an island inverter that does not make a connection to the grid and therefore does not feed back its excess energy to it. Unlike its predecessor, it has a battery charging option, so this type of solar inverter often adapts the voltage to the needs of connected appliances.
- Hybrid inverter. It combines the functions of an on-grid and off-grid inverter. It allows electricity to be generated from photovoltaic modules and can also charge batteries.
Which inverter should we choose?
Once you know what an inverter is, what types we have and what functions it performs, it is time to finally choose a specific device for your own PV installation. When choosing, the key issue is to match the device to the PVs previously selected and the power of the overall installation. Therefore, it is necessary as first to check the minimum MPPT tracking voltage parameter of the inverter. Furthermore, we should pay attention to the efficiency of the inverter (it should guarantee an efficiency of at least 97-98%). Before choosing a specific model, let's compare features and prices, and meticulously read all manufacturer information. Currently, the largest inverter manufacturers are companies such as SolarEdge, Huawei, Growatt, SMA, Sofar or Fronius.