Solar Panel warranties explained and a comparison of warranties from LG, Sunpower, Panasonic, Trina, Hyundai and Kyocewra solar panels?

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Solar panels are a unique consumer product in that their entire viability depends on them continuing to serve their purpose to produce electricity for a long time.

Most solar panel brands offer a power output warranty of 25 years. In consumer electronics terms this is a very, very long time and I can't think of one other consumer electronics product that offers a guarantee that it will continue to work for this length of time.

So when you buy a solar panel, or a solar power system for your home including solar panels you are really paying for two things:

  1. A physical product which is supplied and installed up front and will work day one; and
  2. A promise from the manufacturer that this product, the solar panel will continue to produce for 25 years or more.

This makes evaluating solar panels very different than evaluating most consumer brands because you need to take a view on:

  • Which brand of product is mosty likely to work and be free of defects today;
  • Which brand of solar panels is least likely to develop defects over time; and
  • If the panel does fail over time what defects and failures does each company consider warrantable and which won't they cover; and
  • Which company is most likely to still be in business 10 or 20 years down the track should a warrantable defect arise.

Whilst the first two points above the things that are considered on all consumer purchases the third and fourth point above are particular to the nature of solar panels as a product. In particular the final point relating to the likelihood that a solar panel company will exist in the future is particularly important given the very long life of the warranty and the real likelihood that any performance problems might occur at the tail end of that 25 year guaranteed working life.

But first, let's start by explaining the three basic warranties that you get when you get a solar company to install solar panels on your home.

 

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Product Warranty

Product Warranty is usually for 10 years and it refers to the structural completeness and integrity of the module. It is different to the power output warranty. It essentially says that the panel will remain structurally intact and free from physical defects for the Product Warranty Period.

However, there are a number of exclusions and requirements that you have to meet before you can claim under the Product Warranty for a panel.

lg solar panel warranty information

Here is an example of some of the standard exclusions that you will find in Product Warranty Document.

This is an LG solar product warranty document but most manufacturers have similar terms:

  1. Fair wear and tear;
  2. Modules where the serial number has been removed or made illegible;
  3. Modules which have been subject to misuse, abuse, neglect or accident;
  4. Alterations, improper installation or re-installation;
  5. Damage and/or failure caused by improper wiring;
  6. Damage and or failure caused by other parts of the solar system;
  7. Modules which have been installed in mobile units such as caravans and motor homes;
  8. Modules installed in extreme corrosive environments e.g. boats (Please note: Panels installed in residential or industrial areas near the coast are covered);
  9. Incorrect system configuration and damaging installation environments, e.g. installation of mutually incompatible modules, inadequate system design, permanent installations under constantly moving harsh shadows e.g. palm tree leaves;
  10. Modules which have been installed by someone other than a qualified or licensed technician in the solar or electrical business field;
  11. Non-observance of LG's installation and maintenance instructions as outlined in the LG installation manual;
  12. Repair or modifications to the module by someone other than a qualified solar installer approved by LG;
  13. Power failure, surges, lighting, flood, fire, accidental breakage, acid rain, vandalism, acts of war, natural disasters like tornadoes or other events outside LG's control;
  14. In addition, the warranties do not apply in relation to any cosmetic change of the module in appearance over time, if and to the extent such change does not result in an impairment of the functioning of the product;
  15. External marking in the modules such as mold and lichen e.g. transferring from nearby roof tiles, and which occur after delivery to the customer shall not qualify as a defect hereunder

Firstly it is up to you to have the panel tested and returned to the manufacturer. It is not possible for you as a consumer to remove and test a solar panel and so you will usually have to pay the solar company who installed your panels to do it for you. They might agree to do it for free if they are a nice company (and happen to still be in business when a problem occurs) but technically it is not their responsibility as your warranty on the panel is from the manufacturer not from them.

Secondly, a manufacturer will usually argue that damage to the panel was caused in installation and it is impossible for you to prove if this is or is not the case.

A third issue, and the issue most likely to arise is what is a cosmetic defect and therefore not warrantable and what is a material and warrantable structural defect. In this respect an issue arises with snail trails visible in modules and microfractures visible in cells within the module.

It is common that when snail trails and microfractures first appear in cells that manufacturers claim that these defects are cosmetic rather than structural and do not replace the panels under warranty. Usually when these issues first become noticeable the panel is still performing within an acceptable power output range and so you can not have it replaced under the power output warranty.

The problem with this is that there is growing evidence that these snail trails and microfractures can actually develop into hot spots. A hot spot is a short circuit within a cell causing a DC arc (electrons jumping from one side of the fracture to the other) which is effectively the same as an arc welder. A hotspot can get get extremely hot and being driven by DC power can burn continually causing fires. I have seen many burnt out solar panels and solar cells but fortunately in my experience these have never set a house on fire. However, I think it is definitely the case that there is enough evidence that snail trails and microfractures can lead to hot spots that manufacturers should replace panels that display these issues.

graph of power output warranty

Power Output Warranty

The power output warranty for a solar panel is a warranted level of power that a solar panel will produce at standard test conditions (STC) for each year extending into the future.

The industry standard is for a power output warranty is 25 years.

The standard solar panel power output warranty is for the manufacturer to guarantee 90% of the rated peak power at STC for 10 years and that the panel will produce at least 80% of its rated power output between years 11 to 25.

Step down vs Linear Power Output warranties

The standard power output warranty in the industry has always been a straight line step down warranty.

What this means is there is a guaranteed level of power output from 1 to 10 years, originally 80% but in more recent times 90%, then a step down and a fixed guaranteed rate of power output at STC for years 11 to 25.

This type of warranty is still the case for the majority of solar panel brands on the market.

However a number of the leading brands now offer what is called a linear warranty. What this means is that they allow for a small drop in production over the first year and then a linear fall in production each year after that.

Power output warranties for the leading brands, LG, Sunpower, Panasonic, Trina, Rene Sola. Hyundai.

 

This table shows a comparison of the power output warranties offered by each of the leading brands of solar panels

Brand Type of Power Output Warranty Term of power Output warranty Warranted power output at STC step 1 Warranted Power Output step 2 at STC
Sunpower

Consumer reviews of Sunpower
Linear 25 1-5 years: 95% (1% reduction per year for first 5 years) Linear reduction of 0.4% per year from 5-25 years such that 87% of Pmax guaranteed after 25 years
LG Solar

Consumer reviews of LG Solar
Linear 25 Up to 2% reduction for first year Linear reduction of 0.55% per year. 84.7% at 25 year mark
Panasonic

Consumer reviews of Panasonic
Linear 25 Up to 3% reduction for first year Linear reduction of 0.26% per year. 90.76% at 25 year mark
Trina Solar

Consumer reviews of Trina Solar
Linear 25 For polycrystalline panels up to 2.5% reduction in the first year and 3% for monocrystalline Linear reduction of 0.7% per year for poly and 0.68% for mono. 80.7% by year 25 for poly and 80.68 for monocrystalline.
ReneSola

Consumer reviews of ReneSola
Linear 25 2.5% reduction in first year. 90% by year 10 then 80% by year 25. After first year: Linear 0.833% reduction until year 10 and then 0.67% for remaining 15 years going down to 80%.
Hyundai

Consumer reviews of Hyundai
Linear 25 Up to 3% reduction for the first year 0.7% linear reduction rate. 80.2% by year 25.

Installation Warranty

When you get a solar company to install your solar panels for you they will usually offer you a warranty on the quality and workmanship of their installation.

This is important because there is every chance that if you had a problem with either the structural integrity of a solar panel (Solar Panel Product Warranty) or the output of a panel (Power Output Warranty) that the first thing the manufacturer is going to do is blame it on incorrect installation.

This is why the installation warranty comes in handy because it allows you as a consumer to say to both the manufacturer and the installer that one of you must be liable for this issue.

10 year installation warranties have become common in residential solar in America because under some old rebate program this was a requirement to claim a rebate. However, this length of installation warranty is not common in overseas markets.

The most common things that might be covered by an installation warranty are:

  • Water getting into glands and junction boxes;
  • Failed circuit breakers (although this could be argued to fall outside an installation warranty;
  • Solar panels becoming loose as a result of clamps not being secured properly.
solar panels