What Happens When a Solar Panel Fails?
Solar PV panels are pretty remarkable devices. They contain no moving parts, they’re resistant to the harshest of
weather conditions, they don’t need any periodic cleaning or maintenance, and they’ll convert sunlight into electricity
for decades without problems. They’re truly a “set it and forget it” type of device. Yet just like any other technology
product out there in the market, problems with solar panels occasionally surface and require a bit of attention. Here’s
what would happen in the unlikely event that one of the panels in your solar PV system fails.
A Panel Failure Doesn’t Hose Your Entire Solar System
If you deploy a solar PV system for your home, by far your most likely scenario is that your panels will perform troublefree for decades. That’s one of the reasons that they’re typically warranted by their manufacturers for 20-25 years. But
problems do occur from time to time, so if you happen to experience a problem with a solar panel after it’s been
installed, it’s important for you to understand that the rest of your system will not be rendered inoperable—not by a
long shot. In all likelihood, depending on the nature of the panel failure, all strings in your solar array—including the
string containing the failed panel—will just continue running with the failed panel left in place (see below for more
details on panel replacement and interoperability options). In other words, if your entire solar PV system consists of
twenty panels and one failed, your system would likely still operate at 95% of its previous performance until the failed
panel was replaced.
Who’s Responsible for Replacing a Faulty Solar Panel?
The responsible party for addressing a solar PV panel failure depends on a few key factors, including (1) who owns the
solar system, (2) whether the panel manufacturer is still in business, and (3) whether an identical replacement for the
failed panel is still available in the market.
The chart below outlines the most common scenarios that you would encounter if your solar PV system experienced a
panel failure.
Availability of Original Solar Panels
Solar System Ownership
Homeowner (purchase)
Lessor (lease to homeowner)
Lessor (PPA to homeowner)
Manufacturer still in
business, original panels
available from
manufacturer
Manufacturer replaces faulty panel
with original model
(under warranty)
Lessor replaces faulty panel with
original model
- or Lessor credits lessee's monthly lease
fee for unmet production guarantee
Lessor replaces faulty panel with
original model
- or Lessee's monthly PPA fee is lowered
due to reduced system production
Manufacturer still in
business, original panels
no longer available
Manufacturer replaces faulty panel
with compatible substitute
(under warranty)
Lessor replaces faulty panel with
compatible substitute
- or Lessor credits lessee's monthly lease
fee for unmet production guarantee
Lessor replaces faulty panel with
compatible substitute
- or Lessee's monthly PPA fee is lowered
due to reduced system production
Manufacturer out of
business, original panels
available on aftermarket
Homeowner purchases and replaces
faulty panel with original model
- or Homeowner continues using system
with degraded performance
Lessor replaces faulty panel with
original model
- or Lessor credits lessee's monthly lease
fee for unmet production guarantee
Lessor replaces faulty panel with
original model
- or Lessee's monthly PPA fee is lowered
due to reduced system production
Homeowner purchases and replaces
Lessor replaces faulty panel with
Lessor replaces faulty panel with
compatible substitute
- or Lessee's monthly PPA fee is lowered
due to reduced system production
Manufacturer out of faulty panel with compatible substitute
compatible substitute
business, original panels
- or - or Homeowner continues using system
Lessor credits lessee's monthly lease
unavailable
with degraded performance
fee for unmet production guarantee
As you can see, in most instances you would not incur any out-of-pocket expense to completely rectify a panel failure.
And even in those rare instances where you needed to bear the financial burden of replacing a solar PV panel yourself,
doing so would neither entail a significant capital outlay nor an expensive service call. Solar PV panels are relatively
straightforward to swap in and out, and most new panels only cost several hundred dollars to purchase in today’s
market (and will undoubtedly cost less than that in the years to come).
Panel Replacement and Interoperability
Replacing a faulty solar PV panel with a new one of the same model maintains complete interoperability with the rest of
your solar system. What you may not know is that that same level of interoperability is frequently achieved with the
introduction of other solar panel models into your solar system—even those from other manufacturers.
If the original panels in your solar system were discontinued and no longer available in the market, then a compatible
substitute could be used to replace a faulty original panel. Within the context of solar PV systems, a compatible
substitute would need to have similar electrical characteristics as your original panels (specifically, the same volts at
open circuit [VOC] and volts at maximum power [VMP] ratings). Most of the solar panels in the market today have
similar VOC and VMP ratings, and are therefore electrically interchangeable.
Solar panel interoperability between different models and manufacturers becomes even less of an issue if your solar
system contains microinverters as a shade mitigation solution. With microinverters, the DC power created by the solar
panels is converted to AC power right at each panel itself, which electrically isolates every panel in the array from every
other panel in the array. That’s how microinverters are able to mitigate the effects of shading. But it also comes in
extremely handy in ensuring that virtually any replacement panel can be inserted into your solar system as a substitute
for one of your original panels if there was a panel failure. With microinverters in the equation, your panel replacement
options become virtually limitless.
Leave It, Remove It, or Replace It?
Finally, it’s worth saying a few more words about how your solar system performs when a panel fails. As mentioned
earlier, whether or not a single panel failure affects the performance of other panels in your system depends on the
nature of the failure. In the absence of microinverters, if the panel failed in a way that still allowed electrical current to
pass through it (even though it was no longer producing power itself), the production from all other panels on that string
would not be negatively impacted whatsoever. However, if the panel failed in a way that affected one of its bypass
diodes and current could no longer flow through it, the bad panel would “take down” its entire string and you would
only get production from the other strings of panels in your array. If that happens, then you’d definitely want to at least
remove—and likely replace—the failed panel in order for the remaining panels on that string to pass electrical current
and resume their full production.