One of the most fundamentally important electrical components in your PV system is your inverter, as, without it, you cannot supply AC from your DC-powered solar array or batteries to your home appliances and devices.
The solar inverter works by converting DC from the solar array or batteries into AC to power your home appliances. The inverter is a crucial component in any PV system where AC appliances and devices will be powered as home appliances cannot operate off DC.
We will look at the following in terms of understanding how a solar inverter works as well as the additional functionality it provides for the PV System:
- How the solar inverter converts DC to AC
- The different kinds of solar inverters and their differences
- What other role the inverter plays in terms of safety and monitoring
Knowing how solar inverters work, as well as the different options, will help you make the right choice for your PV system, so let’s dive right in!
A Solar Inverter Converts DC To AC
Using a transformer in the inverter, the DC current received from the solar panels or the battery is transformed into AC current and transmitted to your electrical supply.
Solar panels only generate DC electricity, and this is due to the way the panels work with the sun’s rays and the photovoltaic cells in the panels. When the energy contained in the sunlight strikes the PV cells, it causes an electron to be released, and these electrons flow to form a Direct Current.
The DC current created can then either flow to the batteries for storage and later use, or it can be transmitted to the home directly for use in the electrical system. Since most homes in the US and worldwide use either 120V or 240V AC, the DC current has to be converted.
The solar inverter utilizes a transformer and ‘inverts’ the current from DC to AC by running it through two transistors that switch on and off super fast and emit an AC current to power the AC appliances and devices.
What Else Do Solar Inverters Do?
Besides converting DC to AC on your solar array, inverters also offer system monitoring, grid interface if you are grid-tied, power production, and safe system operation as well as maximum power output.
See also: What Is A Solar Inverter? (Explained With Examples)
Monitoring Solar System
All inverters will offer system monitoring, whether it be a whole or individual panel so that the owner can determine how well the system is performing and if and where any adjustments need to be made.
Communicate With The Grid
Smart inverters communicate with the grid and, thanks to advanced installed software, can regulate adjustments to voltage changes, frequencies, and minor disturbances like changes in voltage.
Diagnostic Reports
New technologies allow you as the owner to view and track power production and performance via apps and other digital interfaces so you can view stats, errors, and inverter diagnostics on your phone or laptop.
Safety Measures
From a safety perspective, as materials and connections age, the risk of electrical arcing increases, and inverters, especially some of the latest ones, are equipped to detect arcs and ensure the safety of operation and will switch off accordingly.
Optimizing Power Output
Solar inverters also play a role in optimizing the power output of the system, especially power optimizers and micro-inverters that reduce the impact of shade on power output and generation.
What Kinds Of Solar Inverters Are There?
There are essentially three types of solar inverters available: string inverters, power optimizers, and micro-inverters.
String Solar Inverters
As the cheapest, oldest, and most popular type of solar inverters, this type allows groups of panels to be connected via strings (hence the name) and are usually located on the side of the house, near the ground for easy access.
The groups of panels are then connected to a single inverter via strings to deliver the generated current for use in the home.
They are very reliable, but they had some restrictions on their capacity to deliver full power in the past. For example, if one or a few panels were in the shade and their generation capacity was diminished, this would cut the generation output of the entire string of panels.
String inverters also can’t monitor individual panel performance, and could only monitor the full system generation capacity, limiting the analysis and optimization of the solar array.
These were typically installed where the solar panel array all faced the same direction and didn’t suffer from extended shading. Modern upgrades to string inverters have made them more versatile.
Power Optimizer Solar Inverters
This type of solar inverter is designed to optimize the array’s power output and is placed at each panel. Unlike micro-inverters that convert DC to AC at the panel, these inverters stabilize and condition the current to maximize the system efficiency.
Where the panels may be exposed to shade, the power optimizer will continue to deliver maximum generation to the central inverter, and this won’t diminish the array output as it would with a standard string inverter.
Because these inverters are located at each panel, individual panel monitoring can be done to assess and analyze individual panel performance and full system performance.
Solar Micro-Inverters
Similar to the power optimizer inverters above, the micro-inverters are also located at each panel, but the difference here is that these little powerhouses convert the DC to AC at the point of generation and that current is then distributed to the house electrical supply.
So you don’t require a central inverter if you have these installed, and so your system can be easily expanded if need be, at a later stage. Not only that, but micro-inverters prevent the overall decrease in system generation output if there are panels that have shade.
Where that occurs, those shaded panels will simply produce less power, but the system itself will not lose power. Micro-inverters also allow individual panel assessment, and where shade is a problem, panels can be relocated to better positions.
Micro-inverters are the most expensive type available, but you save money as you don’t require a central inverter with power optimizers and string configurations. The only real drawback to the micro-inverters is repairing them.
Since they are mounted on the back of the panels, should one need replacing, it can be an inconvenience to access them.
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