Having solar panels on the rooftop has become so common that we’re no longer surprised to hear the PV small talk at dinner parties.
‘You have a solar system installed? Oh, wonderful darling. Which inverters did you choose? Chicken tastes fantastic, please pass me the salt love.’
Of course, it’s amazing to have such technology that can produce electricity out of sunlight. But when it comes to the different components, our minds and eyes still boggle about how on earth it works.
No need to be shy—it’s only in the past few years that solar PV has gone mainstream. Nobody explained it at school.
This article about different types of inverters will bring some understanding into your life, no matter if you are looking into going solar yourself or just want to participate in dinner table conversation.
So when we hear the terms micro inverters or string inverters, what do they mean and what do they do?
What Does an Inverter Do?
Let’s tackle what an inverter is and how it works with solar panels.
In simple terms, solar panels produce DC power. DC power is when electrical current measured in amps flows in a constant direction.
Batteries work with DC power and so do a lot of motors. Our homes though—and the electrical grid—use AC power.
So having a solar PV system that produces DC power doesn’t help us if we need AC power in our home environment.
The inverter at its most basic function converts the DC power generated from your solar panels to usable AC power that is used in your home.
Another important aspect of PV inverters is that they must be sized according to the total size of your PV system.
As an example, if you have twelve solar panels installed totalling 3kW, then you’ll need an inverter that is rated at 3kW or larger.
PV inverters can also be classified as being the brains behind the solar PV system.
On top of converting DC power to AC power, it manages the power produced by improving efficiency and having controls to better manage the energy produced.
Most modern PV inverters nowadays include monitoring systems to inform the homeowner how much electricity is being produced and when.
They also include diagnostics to assist installers in identifying faults.
Modern PV inverters are upping their game when it comes to communications, with most of them offering Bluetooth and Wi-Fi functionality.
It gives you the opportunity to monitor your PV system when not at home or letting your PV installer monitor the system remotely in case of any technical issues.
What Are the Different Types of Inverters?
Of all the inverters, the most common one found in most residential installations is the string inverter.
You’ve probably noticed that solar panels are installed in rows, and in the solar power lingo these rows are called strings.
Strings of panels are connected to the string inverter, hence the name string inverter.
Multiple strings can be connected to a string inverter. Each string produces DC power and provides that power to the inverter and outputs AC power on the other end.
Depending on the size of your solar PV system, multiple string inverters might be needed.
String inverters have been around for a long time with a whole multitude of brand names out there. They’re reliable and suitable for solar PV systems where there’s no shading issue.
Also, they’re good for cases when your PV panels are all facing the same direction or you have two strings of PV panels facing different directions.
Central inverters are like string inverters but more suitable for the utility-sized solar PV systems, where typical PV installation sizes are 100kW and upwards.
Large arrays of solar panels are all connected to a single combiner box and from here all the DC power runs to a central inverter.
Central inverters have some advantages over string inverters for large solar PV installations. They are more cost-effective than having loads of string inverters in a large PV installation.
Yet one disadvantage is their single point of failure: if the central inverter goes down, then the whole PV system stops producing electricity.
Solar Hybrid Inverters
Now, what on earth is a solar hybrid inverter?
A solar hybrid inverter is a cross between the traditional grid-tied and off-grid PV inverter.
It serves the purpose of converting DC power to AC power, supplying your home with clean energy, and it also acts as a battery management system.
It is responsible for charging your solar batteries with your clean electricity and managing that power from the batteries.
You can consider this type of inverters as an intelligent energy management system for your home, managing all aspects of energy production and what’s done with that energy.
Finally, we come to the ever elusive micro inverter! It’s a new technology in the solar PV game.
A micro inverter is a small inverter that is installed under each solar panel, so you have one micro inverter per solar panel.
They serve the same function as a string inverter, but have many advantages over string inverters—we’ll get back to that a bit later.
As micro inverters are still a relatively new technology and as such don’t have a long track record compared to other types of inverters, the jury is still out on their reliability.
The Advantages & Disadvantages of Micro Inverters Over String Inverters
A major advantage of micro inverters is their ability to increase the efficiency of the solar system by managing the energy production at the solar panel level.
As you know, if one of the panels is covered by shade or is exceptionally dirty, then this affects the performance of the entire solar string array. And the string inverter also.
Micro inverters, however, can compensate for this by managing the energy output of each PV panel independently, thereby increasing the efficiency of the solar power system.
Micro inverters are also suited for oddly shaped roofs where the PV panels face different directions.
Another advantage of micro inverters is that there’s no single point of failure. If a string inverter goes down due to a technical fault, then the whole PV system stops producing power.
With a solar PV system using micro inverters, if a microinverter fails, then only one PV panel is taken out of the equation.
Manufacturers of micro inverters also claim they have a longer lifespan and offer warranties from 10 to 25 years.
One of the disadvantages of micro inverters is the actual cost compared to string inverters, as more hardware is needed.
More electronic equipment also means more things can go wrong. That’s why we say less is more.
Maintenance and replacement costs might be higher.
As more effort and time is required to replace them, consider the roof access needed by installers.
What is a DC Power Optimiser?
Power optimisers are DC/AC converters and are also installed at the solar panel module level.
A solar PV array is producing electrical energy optimally when all the solar modules are performing the same.
But individual panels can be impacted by dirt, snow or shade, etc. All these conditions have a negative impact on the overall solar PV array output.
This is where the power of power optimisers comes into play, pun intended!
Power optimisers are constantly monitoring the array voltage and current and work to mitigate mismatch effects so that each module can operate at its maximum power level.
This results in optimal energy harvest for the entire solar PV array.
Should I, or shouldn’t I?
Micro inverters and power optimisers are premium products, and as such have a premium price attached to them.
Before investing in the technology, one has to consider the type of roof setup you have and the environment the panels will be exposed to.
If the requirements for the micro inverters or power optimisers tick all the right boxes, then it could be a good option.
It’s best to talk to your solar PV installer though, as they are experienced in this field and can advise the best route to take following a site assessment.
If you want to see how much solar or battery storage could save you over the next 5 years, then take our solar saving calculator quiz below!
Or talk to an Instyle Solar expert about the best solutions for home energy storage or PV-panels.
Otherwise, head back to the solar blog to find even more great educational content.