Electronic – the failure mode of a solar panel

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I have understood that solar panels don't last forever. Warranties are typically a couple dozen years, and you can expect your panel to last for perhaps twice the warranty period.

But what does exactly happen when the panel is failing? Does it fail suddenly like computer hard disks, or does its output degrade like the capacity of batteries? What are the physical principles behind the failing solar panel? Is the failing in some way related to heat?

Do solar cells made by a reputable brand last longer than cheap Chinese cells?

Is it possible to make a solar panel that would last essentially forever given a high enough price is possible? Such a panel might prove useful if it turns out that the low interest rate environment will continue.

Of course, there are many types of solar cells, so the answer may be limited to the most common types, i.e. polycrystalline and monocrystalline silicon cells.

Best Answer

Reading here and a couple other places makes it sound like solar panel degradation varies widely. Manufacturing origin doesn't appear to be correlated to longevity or if it is, it may be opposite what we expect (China appears to do well). The general gist is that you'll lose a fraction of a percent every year on average. It's likely due to high energy photons slightly changing the structure over time. Weathering is also a concern. Wind-blown sand scratching the surface and dust blocking light are two other ways cells degrade. Most solar installations appear to be able to handle 20-40 years of use without issue, but some don't appear to handle thermal cycling well. In that case, you can have catastrophic failure of one or many cells causing poor solder bonds to break, delamination to occur, or entire cells to crack. Corrosion of the cell and connectors could be another late game failure mode.

I think more of a concern than the cells degrading is the supporting electronics (inverter) dying. The cost of installing a solar installation these days is largely being determined by peripherals rather than the panels themselves. Power electronics to support the system and their failure mode is really what I would be researching if I were in your shoes as I believe the likelihood of catastrophic failure there is much more likely in a much shorter timeframe.

This looks to give a great rundown of many manufacturers and their lifetimes. I've included a diagram from there below: enter image description here

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