Solar Panel Warranties

Your solar PV panel system will consist of a set number of solar panels, an inverter, or micro inverters, SolarEdge, a mounting frame and small components.

Often home energy storage systems or batteries were added to later systems, after 2014 batteries and storage systems started to become commonplace to be installed alongside the PV generating system. (Solar panels, or modules as they are known professionally)

The warranties typically associated with the solar panels are long. Usually a standard 2-year parts and labour, and 10–20-year product warranty. It is useful to note that a reputable installer such as SolarTherm UK will also offer at no extra charge a 10-year insurance backed warranty. Largely this is a backup if the installer is unable to return and has ceased trading.

If installed correctly, a solar panel could last 25-40 years although they have a slight degradation rate and will very gradually diminish in their efficiency.

Should you worry? 

SolarTherm UK have installed hundreds or thousands of solar panels since 2010 and although we do hold a small stock of spares for each model we have ever installed, it is very un-common to see a solar panel malfunction or die. Excluding the occasional early days bad batch, we have probably seen less than 600 failures in around 25,000 systems installed across Europe.

The common inverter pre-2014 was usually a grid tied inverter, and SolarTherm UK usually opted for SMA sunny boys, Fronius, Mastervolt and Samil. Our optimised systems were usually TIGO and post 2014….Solaredge!

SMA usually had a 5–7-year warranty. The units were bulletproof and very occasionally they did and do fail. Many are still working perfectly on inspection, and we do not get advised by homeowners that they have encountered issues on a regular basis.

Fronius usually also had a 5-year warranty, failures are a little more common, especially now at the time of writing with some hitting the 10+ year mark, but still, most are going strong.

Samil had a 10-year warranty if installed by an accredited installer. The units were more sensitive, and do not like over-voltage. It is true to say we have swapped out lots of Samil inverters, but largely they were underrated and poorly installed by others. The warranty was never honoured by Samil, and reputable companies such as SolarTherm UK bore the brunt of the costs. Largely we advise an upgrade to SolarEdge.

Mastervolt had mixed reviews on the larger units, luckily, we mainly only used Mastervolt Soladin 600 units, and the 1-1.5kw. The Soladin were only rated at around 700w max, and often we used these to connect the odd two panels when trying to squeeze as much as possible on awkward roof spaces. We have lots still running to full capacity, they do ‘pop’ if they were really stretched, especially when attached to higher voltage modules.

Oddly, one of our best-performing systems contains Mastervolt Soladins, which we believe is because they used extraordinarily little power to convert the DC electricity to AC.

Tigo – No problems here. Largely installed with one of the above inverters, this optimised and portal enabled system will notify both the owner and us of any fault within the system. TIGO have long warranties and are good at sending replacements free-of-charge when in warranty if they fail.

Solaredge, by and large our most successful roll out. SolarEdge are an amazing company and have many benefits. SolarTherm UK is a UK strategic partner and advanced installer of these systems. Often older systems on the higher Feed in Tariffs will benefit greatly from an exchange of the older grid tie inverters to a SolarEdge system. The warranties are 10 years for the inverter (extendable for an extra cost) and 25 years for the optimisers.

The installer will need to be SolarEdge accredited and the supplier of the goods bona fide before the homeowner can benefit from better warranties.

Like any other product, SolarEdge can be advised when not required, replacements of inverters to SolarEdge are not always necessary.

Older systems at a standard 20–40-degree pitch with a due South orientation suffering almost no shade using a well-matched SMA and crucially having perfectly matched high quality solar modules will see low increases in energy performance. However, the benefits of safety cut out to 1v per module, you and us being able to see all panels working live. Fault prompting and panel miss match speak for themselves.

It can be a personal choice to upgrade to the newer SolarEdge equipment if the current system is working well, but a proper assessment including electrical testing of the original PV array needs to be undertaken. Unfortunately, taking someone’s word over the phone or a man in a shiny suit sat on your sofa telepathically suggesting your system is underperforming is not the way forwards.

Some sales personnel are now even ‘inspecting’ the system to confirm a failure or underperformance.

As per our previous blog posts… DO YOUR DUE DILIGENCE CHECKS before signing on the day. Ask what his electrical qualifications are, what accreditation body they are with and do not be afraid to check.


No one has a bona fide warranty to sell to you to cover all the systems components. Yes, that is correct. You do not need, neither can you purchase from a reputable company a warranty or insurance that will completely cover your existing system.

There is no British Gas or Homecare type breakdown cover available. No inverter or module manufacturing facility is offering a home call out or a blanket cover and despite assurances over the phone or typically in your lounge. A sales agent is committing fraud when suggesting this and unfortunately we have evidence showing payments of between £5-11k being paid to these ‘companies’ to cover your system.

Of course, some of you are thinking who on earth would pay £5k + for a warranty for a system that you could possibly now completely replace for a similar sum. Sadly, the same people that bought Solar PV systems 7-10 years ago, sometimes as a retirement plan, already in their twilight years, are being duped by this, not occasionally but regularly!

NOT MUCH IS BEING DONE ABOUT IT, and when it is, sadly it is usually too late.