How Inverters Work

The Solar inverter

The solar inverter is a vital part of your solar system. The electricity created by the PV panels on your roof must be converted from DC (Direct Current) to AC (Alternating Current), the standard current in the electrical grid and in most commercial home appliances. One way to understand the role of a solar inverter is to think about the components of a car’s powertrain.

If the solar panels on your roof are what powers your system, like an engine powers a vehicle, then the solar inverter could be compared with the car’s transmission.

We all know that a motor alone, cannot bring you from point A to point B. You need a way to transmit the engine’s high-speed rotational force (or torque) to the axle in order to turn the wheels, which are in contact with the road, and therefore make the car move. However, the wheels rotate at a much slower speed than the engine.

If you tried to connect the engine directly to the wheels, they would turn so fast you would have no control. The transmission makes sure the rotational speed of the engine translates to an appropriate wheel speed. It also sends energy to the differential, which enables two different wheels to rotate independently at two different speeds during a turn.

This is a complex system, and so is a solar system, with the solar inverter playing a key role.

AC-DC and that’s not Rock-‘N’-Roll

There are different kinds of inverters—inverters for charging a battery, inverters to supply power for off-grid living, and grid-tie inverters. As most solar installations are grid-tie, we are going to explain the functionality of a grid-tie inverter.

The Inverter is the link translating electrical messages between the solar panels and the grid. There are two translations that need to happen. First, we need to translate the DC (Direct Current) from the panels to AC (Alternating Current) as our grid is AC. Then, we need to synchronize the sine wave of the grid to the sine wave of the inverter. (A sine wave is a type of graph that uses repetitively curving lines to represents the cyclical interaction between positive and negative voltage.)

This synchronization is not easy. Not only does the inverter needs to make sure the frequency of the sine wave is equal to the frequency of the grid, the inverter also makes sure that both sine waves run parallel to each other and not shifted (Phase shift). 

Below is a graphical representation of two shifted sine waves which, in the case of voltage sine waves, cannot be connected to each other.

Luckily, we don’t need to worry about this all as this is done within one (box) module, the inverter. In the video below we show a live inverter included in the power center of a 18Kw (18.000 watt) system.

The inverter is also like the brain of the solar system. Most inverters also measure the power that is produced at the moment and also over time, and then shows that information on a display. Most modern inverts also can display that information on a webpage so you can see what your very own solar system is doing wherever you are.

Just like the transmission in your car, the solar inverter is a complex, but very vital, part of your solar installation. Without it, your solar system cannot function. However, unlike the transmission, the inverter has no moving parts, so it is much more reliable. The inverters we install are warrantied anywhere from 10 to 25 years, depending on the manufacturer and the warranty option that is chosen.

We hope that you now have a better understanding of this concept and how the inverter fits within your solar system. Education is one of our core values. At Belmont Solar we are all about Performance, Education, and Neatness (PEN). PEN is our motto.

Now, let Belmont Solar implement your solar inverter project and make solar energy work for you.