What is the expected life span of a solar panel?

[JPin AZ]

I have no idea who made the panel but my controller shows no array current.
I disconnected both battery cables and only show one volt going into the battery, when I first bought this trailer I disconnected the battery and was surprised that the radio was still playing. This is how I found out the rig had solar. Controller appears to be working correctly. I am guessing the panel is 12 plus years old.

 

[TitanMike]

Some claim up to 25 years but far too many factors to consider. The cells in a panel can be damaged by hail, getting walked on, etc.

Bypass diodes ( often just two in panel junction box on back) can fail. Wires connecting panels to controller can break as well as the MC-4 type connectors failing due to water intrusion.

I'd start by disconnecting panel at the roof and measure for voltage. With no load even moderate sun will produce 18-20+ volts. If no output here the panels failed.

If output reconnect and check at input terminals of Solar Controller. If none, bad wire continuity from panel. If voltage is present and no output from controllerthe controller is bad

 

[Aussieguy]

the wire box on the back should contain the diodes
new ones can be soldered in place

this often fixes a zero voltage panel...
new diodes won't fix a a damaged panel with noticeable voltage drop even though panel is in full sun

brown spots and or white(ish) color marks often referred to as snail trails can indicate a damaged panel.
it may continue to work but the voltage will decline.

 

[PhilFromMaine]

Unless you have catastrophic damage, glass panels should last forever at some level of output. I have read that you will start seeing a reduction in efficiency in about 20 years, but the panels will still function.

 

[JPin AZ]

Thanks for the replies. I washed it first and saw nothing wrong with it. I also saw the box underneath but not the connections. Sounds simple enough to diagnose. I am betting bad diodes.

 

[D W]

Heavy snow, ice, wind driven silt/debris, and prolonged exposure to UV Rays. Yes, the sun can damage your solar panels.

 

[jimmoore13]

A consideration...especially given the age.

Solar charge controllers want to be connected to a load (battery) before connecting the panels.
There are very explicit warnings in the installation instructions about this.

Though unlikely, disconnecting the battery from the charge controller while the panels are producing energy can damage the charge controller. Apparently your controller is not fried entirely (assuming this might be the problem), but it might be damaged.

Warning: All testing should be accompanied by a blanket to cover the panel(s) as needed to be able to turn them off.

After you test your panel(s) on the roof and verify power down to the charge controller (pull it out of the wall, disconnect the input wires, and test the wires from the roof for 18 volts +/-), then put a blanket over the panel(s) and disconnect the charge controller's output wires from the charge controller - WITH THE BATTERY CONNECTED. You should see roughly 12.5 volts on those wires...verifying a good connection to the battery bank.

If the panel is putting out roughly 18 volts and you see 18 volts at the input side of the charge controller, and if you have 12 volts at the wires that connect to the output of the charge controller, my hunch is that the charge controller may be damaged from being connected to the panel(s) without a load (when you disconnected the battery).

This kind of damage does not happen often. But given the age of the system, it's not hard to imagine the 12 year old charge controller being more susceptable to damage from being hit with input power and having no load to send it to.

The problem(s) may be elsewhere, but I think this is a test you may need to perform. And, if nothing else, you now know that you must cover your panel(s) before disconnecting the battery bank.