Almost all solar PV systems use today at least one solar inverter, and because this is the central component that binds the whole system together, the inverter is the component that is more likely to fail sooner than other components of the system.
What Is A Solar Inverter?
Modern solar inverters have a more complex functionality compared to the inverters used about a decade ago because solar power has become more popular and is used today in many applications that require more complex functionalities.
The main function of the solar inverter is to convert direct current (DC) into alternative current (AC).
AC can’t be stored for later used, so AC is converted into DC to be stored, and when energy is needed, DC is converted again into AC to power residential, commercial and industrial devices.
Inverter Classification
Inverters are classified after the output, input, type of load, source, etc.
There are small inverters used to power gadgets or a small number of appliances, there are inverters used in residential applications to power homes, and there are large inverters used by solar power plants.
Domestic inverters are available with power ratings between 500W and 10,000W (10KW).
Based on the input accepted, there are inverters accepting 12V DC, 24V DC, 48V DC or even 96V DC.
The most common type of inverter used for residential solar PV systems is the 48V DC, while the 12V DC input inverter is mostly used for portable solar applications.
Solar power plants use inverters that accept an input voltage between 300V DC and 450V DC.
Off Grid Vs On Grid Inverter
Off Grid Inverter
An off-grid inverter is a component of the solar PV (photovoltaic) system that works completely isolated from the grid, and it can’t send or feed electricity to the grid.
If the solar PV system uses an off-grid inverter, the solar panels will be connected with a charge controller, the controller will be connected to the batteries, and the batteries will be connected with the off-grid inverter.
Off-grid inverters can work with portable applications, while grid-tie inverters cannot.
If you want to power your caravan or boat using solar energy, you have to use an off-grid inverter.
Grid-tie Inverter
An on grid or grid-tie inverter can be directly connected to the solar PV system and the grid, and there is also a charge controller option when using a grid-tie inverter because some types of grid-tie inverters can be connected to a battery pack.
The grid-tie inverter is the central component of the solar PV system and the advantage when using this type of inverter is created by the fact that you can use net metering (you can send excess energy back to the grid).
Due to this additional functionality, a grid-tie inverter is more expensive than an off-grid inverter.
Grid-tie inverters can work with batteries, and they have a functionality that can shut down the solar PV system in case of a power outage to prevent islanding.
Islanding can affect the workers sent to fix the grid if the solar PV system continues to send power to the grid (instead of being stopped).
Pure Sine Wave And Modified Sine Wave Inverter
Modified sine wave inverters are more affordable than pure sine wave inverters because they have less circuitry and use transistors acting as a switch to turn on and off the electric current and create a staircase pulse or a square wave.
If you use a modified sine wave inverter, your appliances will tend to overuse power and run hotter (which is inefficient).
However, when using a pure sine wave inverter, your appliances will run much smoother and more efficiently.
Howevere, when using a pure sine wave inverter, your applicances will run much smoother and more efficiently.
Low Frequency And High Frequency Inverter
Based on the speed of the operation of transistor switches in the commutator circuit, we have two categories of inverters: low and high frequency inverters.
A low frequency inverter is much bigger and heavier (uses a large central transformer with iron core), but has several advantages over the high frequency inverter.
Low frequency inverters can manage better difficult loads requiring high surge at the beginning (motors, pumps, compressors, etc.).
Field effect transistors used by low frequency inverters can operate cooler due to the slow frequency of switching required to produce AC power.
Low frequency inverters are available in higher power categories such as: 2,000W, 3,000W, etc.
A high frequency inverter uses way more components than a low frequency inverter, but even so, is a smaller and lighter device.
High frequency inverters are not very well equipped to handle large industrial loads, they are rather used for tools, such as: battery chargers, small appliances, gadgets, etc.
On the retail market, we can find today, mostly high frequency inverters because they are available in lower power categories such as: 300W, 600W, 1,000W, 1,500W, etc.
MPPT And PWM Charger Inverter
A solar inverter is different from a normal inverter because it has a charge controller built into it, and this is the reason why the inverters used by solar PV systems come with either the MPPT or the PWM option.
MPPT functionality allows more power to be drawn out by the solar PV system, an such an inverter is more expensive because it can make the solar PV system be up to 20 percent more efficient.
The PWM functionality is a low-cost solution for small PV systems, but they don’t work very efficiently if the panels are shaded.
All In One Hybrid Inverter
This inverter combines a solar inverter and the inverter charger into one simple unit.
A hybrid solar inverter is a very efficient way to enable self use of solar energy, by allowing the user to store solar or off-grid peak energy to be used during peak times.
IMEON inverters are a good example here because these all in one solar hybrid inverters with integrated MPPT controller use AI (Artificial Intelligence) to manage self-consumption and energy storage.
Interactive inverters can work in hybrid or off-grid mode and they are required only if you want to add batteries to your existing grid-tie solar PV system.
