Sigenergy’s Terminal Problem: Melted Plugs & Throttled Inverters

Sigenergy systems are suffering serious failures, with the company quietly scrambling to address a spate of melted plugs and poor terminations by throttling inverters to stop them overheating, running their own inspections of installs and offering to replace all affected components.

What Is Going Wrong With Sigenergy Installs?

Fires related to home energy systems are extremely rare but for months there’s been a problem quite literally smouldering behind the stylish plastic facade of Sigenergy products.

Inattentive electricians, using a slick, powerful new product, combined with a flawed design, have been producing bad connections.

The result is overheated terminals, melted plugs, burnt out wiring

and now a small fire.

The inverters that are overheating are ensconced in an aluminum case which should prevent any fire from spreading to the battery, but with Sigenergy keeping tight-lipped about a problem they have been trying to manage for well over a month at least, time has come to lance the boil. These plugs are a serious failure and customers need to know.

Fire Incident Linked To Sigenergy Inverter

While a few complaints and pictures of damaged equipment have appeared amongst industry channels, I think most have viewed or indeed hoped this is a minor problem with a small number of outliers.

When there’s literally thousands of installations you expect there will be some hiccups. Anybody can forget to tighten a screw, indeed a “hot joint” is a typical failure in any electrical installation.

However this article comes to you on the back of an eye-opening email sent to SolarQuotes. The abridged version reads like this:

“We write to lodge a serious formal complaint after a near-catastrophic fire incident involving our SIGENERGY Sigenstor Inverter EC 10.0 SP AU 10KW.

Around 2:00 a.m. on 3 November 2025, we were woken abruptly by a power cut which stopped my CPAP machine. We soon discovered an intense burning smell coming from the garage and found the inverter fans were running at full speed despite minimal load and room temperature around 20°C.

We saw visible flames from the inverter. After opening the garage door manually, we moved our EV outside.

Despite repeated flare-ups, the inverter continued to operate, and the fans did not stop. Even the attending fire brigade personnel struggled to locate an effective emergency shutdown mechanism. The system manual provided no clear guidance on emergency shutdown procedures, and the isolator switch was located dangerously close to the area of ignition.

After more than an hour of observation, and in the absence of any emergency contact for Sigenergy, the fire brigade advised us to monitor the system overnight. Only by holding down the red “reset” button was I able to fully shut the unit down.

Arriving later the same morning our installer technician stated, ‘This is the second one I’ve seen.’

This admission raises alarming questions about known product defects and potential systemic safety failures.”

The blue residue is fire extinguisher powder but the blackening shows where flames emanated from the fan grille

This Is A Known Problem

Sigenergy Managing Director for AU & NZ Will Hall told SolarQuotes that “the AC plug problem stems from installers not following installation guidelines, the issue is not due to a product defect” and only a “small proportion of systems have been affected”.

The problem has been bubbling away for some time: Sigenergy issued advice to installers over a month ago reminding them they are voiding warranty if they don’t follow official installation instructions.

They’ve even added a reminder in the commissioning app that installers must acknowledge they’ve made the correct terminations.

Affected Sigenergy Models

Hall told SolarQuotes that his company had found “the issue only applies to single phase 8/10/12kW energy controllers (inverters) which have a different style AC plug which requires the use of ferrules and crimping. To assist installers on future installs we have updated the AC plug on single phase 8/10/12kW inverters so that they are inline with our three phase inverters. This type of AC plug does not require the use of ferrules or crimping which removes the chance of installation error.”

While the 3 phase models look similar, they use a better plug design which so far has proven durable.

The revised single phase plug will use the same lug terminations as the 3 phase units. Why didn’t they just do this from the outset? Well, Sigenergy are promoted as fast-to-install and while lugs are durable, they’re not as quick.

The difference between a properly prepared bootlace termination or a lug terminal isn’t much in the scheme of things, and that’s the frustrating part.

Limits Imposed On Inverters Without Telling Customers

Numerous Sigenergy customers report that the company has limited their inverters without telling them. One affected user posted:

“Could we please have some basic customer communication regarding the current issue with the inverter limiting, including what the problem is and when it’s expected to be resolved? This ongoing bug is likely to have financial and performance impacts for users, and the lack of updates over the past 48 hours doesn’t reflect well on the brand.”

Those affected have only gotten an explanation when they reach out directly to Sigenergy:

“We recently discovered that improper installation could cause the AC plug to overheat and become damaged. To avoid safety hazards, we have limited the operating power of your inverter. We have performed a forced firmware upgrade on your system. This update will continuously monitor the system and protect the equipment and its components … your installer or a Sigenergy authorized service partner will contact you shortly to arrange a convenient time for onsite inspection. High-power operation will be restored after the inspection,” said a Sigenergy representitive in one response. 

Hall told SolarQuotes that “all single phase 8/10/12kW inverters have received a firmware update which allows us to monitor each system proactively. If our system detects sustained full power output of the inverter, it will dynamically and temporarily reduce the AC output slightly to prevent the AC plug from overheating and becoming damaged. This will only affect a small number of installed 8/10/12kW single phase inverters and is simply a precautionary measure in case they have not been installed as per our installation instructions.”

Sigenergy Needs Transparency

Independent solar industry and consumer forums have seen a raft of complaints about burnt Sigenergy plugs. It’s a lingering aroma that’s not going away, but what stinks more is how sanitary the official Sigenergy channels are.

Over in installer support land, there is no melting or burning, nothing to see here. People I trust say they’ve posted to the official account only to find moderation disappears the issue while the support team rings up to solve problems directly.

It’s a powerful way to offer technical advice, no doubt. However it kills off trust, slows results by tying up factory technicians and doesn’t build broader community knowledge.

Other manufacturers use social media to allow an exchange of information between installers. With broad supervision to keep everyone correctly informed, it take less company time and offers faster peer to peer support.

You can’t hide anything from the internet but what I find amazing is that people still try. Sigenergy have repeatedly cracked down on discussions of price on their consumer page. Like that’s going to stop people.

Solutions Are Inbound

In Sigenergy’s defence, they have been proactive in coming up with a technical solution. In fact some installers have complained they had to take a day off to chauffeur the company’s engineers around to inspect installations.

Perhaps the installers were identified as having a number of failures? Can Sigenergy tell via remote monitoring?

I asked on October 27th and November 5th via direct email to the MD and support addresses and further enquiries made by my collegues, but a formal response only came in the early hours of the morning today after persistent demands from Sigenergy to hold off from publishing – representitives say they couldn’t communicate due to requirements from regulators.

In that response Hall said that “our engineers have attended sites where AC plugs have failed and they have determined that the system was not installed as per our installation instructions and we have documented evidence of this and supplied to the regulators.”

Sigenergy’s solution is to modify the design of the troublesome plug.

The rhetoric is that by using the same lug terminals (which feature in the 3 phase models) to connect the wiring, local installers will be more familiar and more likely to get the process right.

The reality is that we haven’t heard reports of similar problems at the same scale among other brands, which makes me think it’s a flawed product from the outset.

Now there is a new design, some installers have flown new stock into the country to fix outstanding warranty claims, because customers have been waiting 7 weeks without resolution.

It’s not a good situation, but we’ve been assured further steps are being taken to address the problem. While a full ACCC recall doesn’t look to be on the cards at this stage, we’ve supplied images to Energy Safe Victoria officials.

I Have An Affected Model, What Do I Do?

The limits placed on inverters are a significant safeguard, but if you still feel uncomfortable, the super safe approach is to follow the labels adjacent your single phase inverter and simply shut it down.

I wouldn’t suggest contacting your installer because they’re already busy, and like us, they have not been given much guidance.

I would however suggest lodging a support ticket.

Provided your installer has used the correct cable (usually black, expensive, multi-strand, flexible) and spent time following Sigenergy’s installation guide to the letter, the risk should be minimal.

However if they used hard drawn, 7 strand, orange circular cable, and reefed it around, bent tight behind the covers in an effort that’s more aesthetic than technically compliant, it could be a serious problem.

Hall said that “we are going to work with installers and our service partner network to proactively replace all installed single phase 8/10/12kW inverters with the updated plug version which reduces the chance of installation error and potential issues with the AC plug. This will be a free replacement. As confirmed by the state regulators and authorities, THIS IS NOT A PRODUCT RECALL as there are no product defects. We are simply updating the design of the product to ensure that installers can install the product with minimal chance of installation error. Once the inverter is replaced, we will also provide the customer with an additional 2 year warranty on the inverter (at no cost) for additional peace of mind.”

Going forward, future installs will include the updated plug.

Installer Complaints About Warranty Work Payment

Sigenergy have a new and novel approach where they have apparently farmed out warranty support to a third party called Omnidian.

I haven’t seen a clear explanation as to how it works, but installers complain they can’t get the same person on the phone when they call back to follow up a problem.

Right now electricians are replacing inverters, as they should under consumer law, but some say they’ve been given no indication on when or even if they’ll be paid.

This must be sorted out, because more than anything, it will incinerate goodwill between Sigenergy and the people who should be their most powerful sales asset.

Victims Of Their Own Success

Sigenergy support was amazingly responsive in the beginning, but as they’ve skyrocketed in popularity, technical support hasn’t followed the same trajectory.

Along with installation bonuses for installers, overseas trips for wholesalers and getting retailers to prioritise customer reviews, part of the aggressive marketing campaign asked SolarQuotes for a desktop assessment in 2024.

They flagged some issues with our writeup then and we welcomed the opportunity to edit for accuracy, but some requested corrections were a bridge too far.

When I mentioned a pair of brackets for every battery wasn’t perfectly simple, Sigenergy protested. Once we explicitly linked to the official installation video, they retrospectively edited that instead. So there’s no voiceover for the wall brackets now.

Ironically I’ve seen two systems literally fall off the wall owing to installer idiocy, which might not have happened if all the brackets were used.

Other Issues Emerging

Sigenergy are still relatively new to the Australian market but secured enormous market share in a short space of time with overwhelmingly positive reviews.

But cracks in their reputation are emerging, and not just with their plugs. There are problems with the AC car charger units as well.

• Commissioning new units on existing sites require phone intervention from support;
• Solar surplus charging doesn’t work when an external export limit is applied;
• Switching between single and three phase charging doesn’t work either.

More generally, Plastic covers don’t always fit properly, making a premium product look pretty ordinary, with the location of the screws causing headaches.

Warranty replacement units are hard to come by, some waiting 7 weeks plus.

Queensland GSD requirements are forcing the use of extra hardware, requiring extra work and return visits.

Building The Plane While It Flies

Sigenergy products boast an impressive array of features that have made them popular across the industry, but we’ll be reviewing their place on the SolarQuotes recommended brand list.

We’ll be closely monitoring the level of the response and whether the new design resolves this issue. One industry expert noted to us that while they’ve had an incredible takeoff, Sigenergy “seem to be flying the plane while putting it together.”

Had a positive or negative experience with Sigenergy products? Detail your experience on our Sigenergy review pages for batteries, solar inverters and home EV charging.