Microinverters Vs DC Optimisers – What’s best?

Microinverters and DC Optimisers compared, and which one is better?

Inverters are one of the most essential components of any solar system. Although solar panels convert sunlight into energy, inverters ensure your home appliances can use the energy. Three main types of inverter solutions are available for purchase, these being;

• String Inverters;
• Microinverters; and
• Power Optimisers.

The two newer pieces of technology are the microinverter and the DC Power Optimiser, which have been increasing in popularity in recent years, specifically in residential and now increasingly commercial solar markets.

Microinverters and DC Power Optimisers are similar in their technology and processes, called Module-Level Power Electronics (MLPE). However, several differences between them will make them more or less useful for your specific system.

So how exactly do these two pieces of technology work?

What do they do?

Microinverters and DC Power Optimisers have a control/converter unit attached to each panel. They can then communicate to adjust the voltage and current on each panel to maximise the performance of the whole series of panels/systems.

This is in contrast to a string inverter whereby all panels connected in the one string will alter the voltage and current, for example, if shade hits one or two panels in the string, leading to output losses.

Similarities

• Both of these technologies were created with innovation in mind, allowing the solar system to produce the most electricity even when some panels are shaded during the day;
• The technology permits the installation of solar panels at various angles and differing orientations (E.g. four panels on the North roof, three on the West roof, two on the East roof etc.) that would not be technically workable with pure string inverters;
• Allows for system growth later with a different power class panel to the original panel’s power class that can be added to the system, which can be very useful with the ongoing changes in panel power classes, e.g. we moved from 300W in 2017 to 430W per panel in 2023;
• If a single panel fails, it does not affect the performance of any other panels. Whereas a single panel failure will affect the performance of the whole string/ series of panels in the case of a string inverter;
• Increases system safety by removing high-voltage DC electricity from the home/ business cables. Whereby 230v AC created by the Enphase  technology, for example, is less dangerous;
• They both are more expensive than a string inverter but claim a higher safety and an increase in performance/output;
• Both technologies are installed at the back of a solar panel; and
• They both allow advanced monitoring of the performance of every panel within the system;
• They both have solid and reliable after-sales service.
• Both key brands now offer a battery solution to go with their product.

Differences

The key microinverter brand in Australia is Enphase, and the key Optimiser brands are SolarEdge and Tigo. While microinverters and DC power optimisers share some advantages, key distinctions exist between the two advancements.

Conversion of electricity

A key distinction between the two technologies is in how electricity is converted. Microinverters convert DC electricity to AC 230v electricity at the panel’s location. This means that AC electricity is pumped from the panel into your house, which is considered safer as AC Electricity is less dangerous than DC electricity.

Although DC power optimisers are likewise situated under the panel, they do not convert electricity independently to AC 230v power. They manage and optimise the DC electricity instead, sending it to a single string style inverter on the side of the house where it is transformed into AC electricity. This control procedure enables the string inverter to convert DC energy into AC energy efficiently.

Inverter warranty

Warranties also vary a little between the two products. For example, the Enphase microinverter warranty in Australia is 10 years but can be upgraded (like most inverters, to 25 years). However, for the Solar Edge Optimisers, the optimiser unit has a 25-year product warranty, and the inverter unit has a 12-year product warranty which is also upgradeable to an even more extended period.

Alternative Power Optimise Brand Tigo also offers a 10-year product warranty on their optimisers. Although an extended warranty on the inverter is usually provided, it will come with an additional price.

Therefore, there is no clear ‘winner’ when choosing one or the other. The main factor will be your home’s situation and the system designer involved. Sometimes the solar installer has a specific preference and will explain their reasons.

Installers

The industry is currently divided into four groups of installers. The ones who prefer Enphase, the ones who prefer Solar Edge. Those who are happy to supply both do not have a preference and installers who strongly prefer string inverters and use Tigo if shade situations occur.

It’s a bit like the Holden versus Ford argument from the past regarding cars. Both fan groups can get very passionate and have little tolerance for the other brand. And do not let me start with NRL clubs…

The one myth we seek to dispel is that these two technologies are prone to fast failure. So detractors have claimed that these products will fail after a few years, as they are located under a solar panel that can reach 80 or even 90 degrees in the Australian summer. However, performance over the past decade has seen both technologies generate outstanding solar output with low warranty returns. This means they can handle the heat for many, many years.

So which one is better – Microinverters or DC Optimisers

Given that they have similar efficiencies and are both reliable technologies with modern monitoring apps, your preferences for some of their key features will most likely determine your choice.

It is also essential to consider that if neither of these technologies tickles your fancy, there is always the trusted string inverter with quality brands like Fronius, Sungrow and SMA.