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SMA Sunnyboy Inverter faults

SMA are widely considered a premium brand of inverter. Their inverters are premium priced too, and for that you can expect quality. However, our experience is that many of the older single phase Sunny Boy models fail at around five years old, often just out of their warranty. Here are some of the most common faults (as shown on the LCD display):

PE conn. missing

This message means that the inverter thinks that something has gone wrong with the a.c. supply. It’s one of the more common error messages and usually there is nothing wrong with the a.c. supply, it’s an internal fault in the inverter. If the inverter is still covered by it’s manufacturer’s warranty then we can liaise with them for you and obtain a replacement unit. Alternatively we can usually get your inverter back up and running.

Varistor defective

This message means that the inverter has detected a component failure. Varistors are sacrificial components that protect the inverter from overvoltages. They wear out with age and in an SMA inverter they are designed to be replaceable. SMA list replacement varistor kits for your their inverters but seemingly no UK supplier wants to stock such low value items. SMA varistors are simply a combination of two standard electronic components and it is possible to cheaply make compatible replacements.

However, this error message can also mean that the inverter just thinks that the varistors are faulty, whereas in fact the fault is with the inverter itself. If your inverter is displaying this error message then there is a chance that replacing the varistors will solve the issue.  However, if the inverter is old enough to be out of warranty then many other if its components are also probably on their way out. Our advice is not to throw any money at it; you are better off replacing the inverter and starting afresh with a ten year warranty.

Solar PV repair enquiry form

For repairs to your solar PV system, please call us on 01772 311016 or complete this form and we will contact you. The more information you give us, the quicker we can help with your enquiry. UK enquiries only please!
Please note that we are a small company and can only offer a call out service within a reasonable travelling time from Chorley, Lancashire. We can send spare parts and replacement inverters via courier anywhere within the UK.
e.g. Are there any fault codes on the inverter screen? Any unusual noises or smells?
If your inverter is at fault then we will definitely need to know what panels are connected to it. Many companies installed a poor choice of inverter the first time round. If we know what your panels are then we can get you the right one.
Your inverter model number and serial number can usually be found on a label on the side or underside of your inverter.
If it's around 5 years, is it over or under? This is important as most inverter warranties are 5 years.
Why do we ask this? Certain companies made consistently the same mistakes/short cuts with their installations.
A picture speaks a thousand words! If you have any photos or other documents that can help us understand your installation then please upload them here. Particularly useful are photos of the inverter model number sticker, the connections into the inverter and an overall picture of the inverter area showing all isolators etc.