The introduction of the MC4-EVO-2 connector has created some uncertainty in the industry. James Patterson clears up the confusion and explains how the industry is working to remove grey areas. 

The Clean Energy Council processes thousands of accreditation applications and compliance reports every year. We see the good, the bad and the ugly of solar in Australia. The CEC’s staff take about 1,500 phone calls a month from accredited installers. Because of this we get a good insight into what is happening in the industry. The tech team members have all been on the tools, so we know how hard it can be to keep up with everything you have to be across in solar. Most of the time we have an answer but sometimes things aren’t black and white.

We have recently received a lot of calls about whether MC4s and MC4-EVO-2 can be mated together. For those that don’t know, the plastic plug connection points on the back of a solar panel are often called MC4s (even though MC4s are just one of the models on the market).

On first inspection, all the brands look like they are compatible with each other because the plastic parts click together. However, the metallic terminals inside the male and female connectors need to be designed to connect so that you can have a safe connection. It’s important to get a good connection between these plugs because otherwise you could get a high resistance join that could result in a fire.

A failure to connect

Discrepancies don’t normally occur when one PV module plugs into another because the modules are normally out of the same box. However, the PV array cable that goes to the inverter installed by the electrician could have plugs from different manufacturers. This is where problems can occur.

Unfortunately, there is no acceptable national or international safety standard defining how these plug connectors should be mated. If there was, there would be a product standard specifying that the male terminal should fit perfectly with the female terminal regardless of the brand.  

In the absence of international standards, Australian Standards require that plug connectors only be mated with those from the same manufacturer and of the same type. This has left many in the industry questioning whether Staubli’s latest product, the MC4-EVO-2, is going to be considered the same type as the ubiquitous MC4 connector.

We have been asked this question a lot at the CEC. Many have produced documentation from Staubli saying that they are designed to be mated. Although common sense would say that these two plug connectors are designed to be mated together, that’s not necessarily what the standards say.

Taking the grey out of solar

We all know that at the end of the day, electricians need to follow Australian Standards in order to avoid defects from inspections, so it is important to get it right.

The CEC is very involved with compliance for the Clean Energy Regulator’s (CER) Small-scale Renewable Energy Scheme, but we are not electricity regulators. We’re not in a position to rule one way or another on a grey area like this in the standards. However, the states and territories have their own organisations responsible for electrical safety, and these bodies have more discretion.

Because of our position, the CEC has better access to the regulators than many electricians, so we can ask the questions for you. We also know that some electricians work in different jurisdictions, so having different rules in different states can be a pain.

Considering this, the CEC has started a Regulators Reference Group, which includes the CER and the electrical safety regulators from the states, territories and New Zealand. The idea behind this is to get answers where the industry is having trouble finding one, and to get everyone in Australia on the same page.

A positive ruling brings clarity

We started the conversation about the MC4 and the MC4-EVO-2 many months ago and eventually got a ruling that as they are from the same manufacturer and are of the same type (MC4), mating the plugs is acceptable.   

However, it was emphasised that until there are international standards on connector mating, any documentation, information or white papers from any other manufacturer saying that their product can be mated with the Staubli MC4 plug will not comply with Australian Standards. Also, terms such as “MC4 compatible” are misleading and should be taken with a grain of salt.

The confusion around the connection of MC4 and MC4-EVO-2 plugs shows that grey areas still exist in rooftop solar and will continue to arise in the future. But by working closely with the CER and electrical safety regulators, the CEC hopes to quickly provide the necessary clarification to ensure that the industry is as black and white as possible.

James Patterson is the installation compliance specialist – standards at the Clean Energy Council.