Solarwatt Solar Panels’ 30 Year Product Warranty Is World’s Best

SolarWatt’s German homepage claims their panels are “Perfekt”. That’s a big call, but their warranty certainly seems as good as it gets.

When it comes to product warranties for solar panels, the American company SunPower has long been king with one that lasts for 25 years.  Not only will they replace any of their panels that fail in that time, but they will send people around to install a new one free of charge and cart away the corpse of the dead panel for autopsy to discover why it died so young.

But SunPower is no longer king.  They have been dethroned. Their quarter of a century product warranty has been beaten by the 30 year product warranty Germany’s Solarwatt has placed upon their double glass panels, which is three times the 10 year industry standard.

That is a very long time.  With the average age of first time home owners in Australia now around 38 years, people could buy a set of Solarwatt panels for their first home and they won’t be out of warranty until after they retire. And maybe they’ll die of old age before any of their panels start to fail.

While in practical terms for most homeowners there is not a huge difference between a 25 year and a 30 year product warranty, But I am very impressed with the confidence Solarwatt has in their solar panels and I am interested in seeing if SunPower will eventually extend its product warranty to meet or beat theirs.

Terminology Note – Double Glass Panels

Double glass panels consist of solar cells sandwiched between two sheet of thin, but seriously sturdy glass.  Another popular name for them is glass on glass panels.  Regrettably, both these terms are far more popular on Google than my preferred terminology, which is crunchy silicon sandwich.

Because glass on glass gives the most Google hits I guess I should call them that, but I think double glass just rolls off the tongue better.  Quite unlike a crunchy silicon sandwich which has no beneficial effect on tongues at all.

Solarwatt just calls them glass-glass panels.  Because they are a German company, this gives me a very strong and I think realistic fear they will hire Vanillia Ice¹ to sing “Glass-Glass Baby“.

Terminology Note – Product Warranty

Solar panel manufacturers provide two warranties with their panels.  The useful one that matters to Australian households is the product warranty.  If the panel stops working it requires the manufacturer to either replace it or at least hand over some cash, depending on the conditions of the warranty.

For tier one panels, which are those considered reliable by major banks, the typical product warranty is 10 years but some will offer 12 or more years.  If anyone ever offers to sell you a solar panel with only a 5 year product warranty, run.  Do not look back.²

Terminology Note – Performance Warranty

The second type of warranty solar panels have is a performance warranty and it is a bit of a con.  They are for 25 or 30 years and guarantee a minimum performance.  They seem reasonable, but the fine print says it only covers panels with performance below a certain level, but not panels that have completely failed and have no performance at all.  Any sensible person would say a panel that is dead isn’t meeting its performance warranty, but apparently the people who write these things aren’t terribly sensible³

Terminology Note – King

I said that SunPower was the King of product warranties, but because Australia has no king (thank god), perhaps I should have said they were the Queen of product warranties.  But to divide people into Kings and Queens solely on the basis of sex seems rather arbitrary to me, so instead I will say SunPower was the Qing of product warranties, which is a gender inclusive term I just came up with.  Also, it was the last Imperial Dynasty of China, which ruled over a mulitcultural empire for 268 years from 1644 to 1912.

Four Reasons Why Their Warranty Is Record Reaching

Solarwatt sells 6 different double glass panels in Europe, all with 30 year product warranties and matching 30 year performance warranties.  I asked a Dutch representative of Solarwatt why they have so much confidence in their panels and I was given four reasons:

1.  Glass is non-reactive.
2.  Their panels resist flexing.
3.  They use high quality epoxy.
4. Their manufacturing process is extremely precise.

Glass Is Non-Reactive

Glass is very chemically stable.  This is why the bottles containing acid in chemistry labs are made of it.  Oh sure, hydrofluoric acid will eat glass, but if you are using hydrofluoric acid, please let me know so I can be sure to never ever go there.⁴

This means they can sandwich their solar cells and the epoxy glue they use between two sheets of glass and be very confident that chemical reactions that could cause the materials to deteriorate will be limited.

Their Panels Resist Flexing

Flexing is bad for solar panels.  While this video shows panels being pounded with artificial hail and and driven over by a ute⁵ without them breaking, this sort of thing doesn’t do them any good at all.

Flexing solar panels can cause microcracks to form in the solar cells and damage electrical connections, causing performance to deteriorate.  This flexing can be caused by wind, snow, or improbably heavy house cats on the roof.  The better a panel is at resisting flexing, the longer it will last and Solarwatt is proud of how hard and stiff they have been able to get theirs.

Replacing a conventional panel’s plastic backing with a sheet of glass contributes to stiffness, and unlike many double glass panels, Solarwatt’s have aluminium frames which further contribute to their strength.

They Use High Quality Expoxy

Epoxy is the sticky glue goo they use to hold the glass and solar cell sandwiches that are their panels together.  It has to be of very high quality so it will do its job for decades and remain clear for all that time.  Poor quality epoxy will yellow with age which reduces light hitting the solar cells and just looks awful.

Apparently it is extremely difficult to use high quality epoxy and not create bubbles when the two glass sheets are pressed together, but I have been told Solarwatt has this process down pat.

Their Manufacturing Is Precise

Now I don’t want to get stereotypical here, but the engineering used by the German company Solarwatt is very precise.  I have been told they have very high quality control and they have very little tolerance for things that aren’t within tolerance.  This makes them very confident their panels will be free of any defects that would appreciably contribute to their deterioration as they age.⁶

For Super Lightweight Panels They Are Pretty Average

The very first point Solarwatt make about their glass-glass panels on their datasheets is they are “super lightweight”.  But they don’t actually say how heavy they are, which is kind of important information.  It seems their quality control has slipped up here and it will be interesting to see how long they will tolerate this mistake now I’ve sent them an email pointing it out.

I looked up the weight of other double glass panels and performed some calculations to account for the thinner glass Solarwatt uses and worked out they might be just under 20 kilograms.  Then I got a message from Zygmunt Nejman, the Managing Director Solarwatt Australia, who told me they are 19kg.  So I felt pretty good about my estimate and I am feeling very confident about my chances in this year’s Guess My Solar Panel’s Weight contest.

A total of 19 kg is very light for double glass panels, which are generally around 23kg, but as far as conventional solar panels go it is pretty average.  Manufacturers generally regard 20kg as the limit for easy rooftop installation and I am impressed to see double glass panels come in under it.  I had doubts it could be done.

Solarwatt Panels Are Made In Germany

Solarwatt manufactures their panels in Germany.  This may come as a surprise because it wasn’t that long ago Germany was disassembling their production lines and moving them to other countries.  But times they are a changing.

In the past low cost labor was a significant contributor to keeping the cost of solar panels down, but far less labor is now needed.  New solar panel manufacturing plants are highly automated with a limited number of actual humans.  This is because using machines for most processes is now cheaper than cheap labor and robots can work with greater precision and consistency, which is very useful for quality control.

As a result, solar panels can now be manufactured where ever the cost of building robo-factories is low, rather than where labor is cheap.

We May Get Complete Replacement For 30 Years

In Germany if a Solarwatt panel fails they will send someone around to your home and replace it with a new one.  They won’t just hand over a bit of cash and say, “There you go, sort it out yourself.”  I think they may even provide compensation for electricity generation lost due to a defective panel.

Solarwatt told me they are considering whether or not to have a full replacement warranty in Australia.  They are a little concerned about how Australia is a bit larger than Germany which means replacing panels that are beyond more than one or two black stumps can get very expensive.  We will have to wait and see exactly what the terms of their warranty are when they become available in Australia.  Presumably this will be soon, as they are looking for installers to partner with.

Are They Worth It?

I don’t know anyone in Australia who currently has Solarwatt panels installed and I certainly haven’t known these people I don’t know for 30 years.  But Solarwatt has done a good job of convincing me their panels are highly reliable and they are not just relying on people forgetting their panels have a multi-decade product warranty.

But their panels do come with a hefty premium.  Solarwatt gave me an estimate of the retail price for Australian households of $1.40 a watt.  That is a lot more than the cost of panels with a puny 10 or 12 year product warranty.  So you will have to decide for yourself whether or not it is worth it.

Personally, I am tempted to buy a set just to see if I can outlive the warranty.