Micro-inverters vs string inverters

When it comes to choosing the right inverter for your solar system, the question of whether micro-inverters are better often arises. Usually, our answer is no, here’s why:

Difference between micro-inverters and string inverters

Firstly, you need to understand the difference between a micro-inverter and a string inverter. 

A string inverter is a centrally located device connected to multiple solar panels in a series, or “string”. It converts the DC electricity the solar panels produce into AC electricity that your home or business can use. 

On the other hand, micro-inverters are small inverters that you install on each solar panel. They work in a similar way to string inverters, converting DC to AC individually at each panel. This allows each panel to operate independently rather than as a string.

So a  micro-inverter and string inverter do the same thing, one just does it for a string of solar panels, and the other for one panel.

Shading

One of the main reasons you hear “micro-inverters are better” is because they handle shading better. And that used to be true.

Historically, if shade affects one solar panel, it would reduce the performance of the entire string of panels. For example, if shade reduced the performance of one panel by 10%, all panels would drop their performance by 10% to match.

However, with modern technology in high-end inverters, this is no longer a major issue. The Maximum Power Point Trackers (MPPT) are now advanced enough that if you get yourself a good quality inverter, a little bit of shade from a tree, pigeon, or cloud won’t affect the other panels on your roof.

A French study found the performance between systems with micro-inverters vs string inverters was basically the same.

Several tests have been set up in Australia in recent years, to test micro and string under different shading scenarios…the outcome was the same.

Price

What is not the same? The price. On average, using micro-inverters will make your installation about 30-40% more expensive. This is because you have to buy more components, and the installation takes longer.

Because you have more components, there are more things that can go wrong. As the micro-inverters are on each panel, if something does go wrong, you need the installer to get back on the roof and take the panels off to be able to fix/replace a micro-inverter.

When might we suggest micro-inverters?

We aren’t saying micro-inverters are never a good option. We certainly recommend them if the situation calls for it.

For example:

• If you value per-panel monitoring, then micro-inverters may be worth the extra cost.
• We might suggest micro-inverters when a house has been pre-wired to suit. Often when people are building they’ll get the house pre-wired for solar, even if they aren’t ready for the system at the time – this is a great idea. However, depending on who has done the pre-wire, and how long ago, it may be set up for micro-inverters with AC cable running to the roof. In this situation, it can work out more efficient to use micro-inverters.
• Some hip or complex roofs mean the best solar design is to incorporate many different aspects of the roof. As Micros are independent on each panel, you can use all aspects without worrying about having enough panels in a string (for a string inverter).

When completing a site visit we look at all of these factors to determine what option is best for you. Contact us to book a site visit today.