Solar Panels By The Sea And Corrosion Resistance

If you are putting solar on a house by the sea then I’m jealous! And I also need to tell you about the IEC-61701 standard.

Oh, I do like to be beside the seaside,
I do like to be beside the sea…

Ever wonder why you never hear a robot singing that song? I’ll tell you why.

Two words: corrosion!

Sorry, that was one word. Two words – bad corrosion!

When they sit on the beach and watch us swim in the salty sea robots regard us with envious eyes. They positively turn green with envy. Or possibly galvanic corrosion.

And it is not just robots, but anything metal which can suffer corrosion on the coast including solar panels. Wind and waves can cause sea spray to be carried well over 100 meters inland and any solar panel within the sea spray’s reach needs to be especially corrosion resistant.

Fortunately, there are a large number of solar panels suitable for use by the seaside. If you ensure the panels you install meet the proper standard for corrosion resistance you shouldn’t have any problems.

Solar Panel Corrosion Resistance: What To Look For

A standard for salt mist resistance for solar panels has been set by the IEC or International Electrotechnical Commission.

Panels have to meet a standard called IEC 61701 to be suitable for installation near the sea. 

This is an easy number to remember as everyone knows 617 was the year Sigeberht the Little was crowned King of Essex. He was built like Humpty Dumpty and resembled a 0 and he was 1 meter tall. So 61701.

If you want to remember the whole thing, just pretend IEC stands for I End Corrosion.

But even though the standard is easy to remember there is probably no need to. Most solar panels that meet it will proudly proclaim that it has, “Salt mist corrosion resistance” on its datasheet. Solar panel datasheets are rarely shy about this sort of thing.  If they’ve got it, they flaunt it and won’t hide their corrosion resistance behind a number.

So far the datasheet of almost every tier one panel I’ve checked says it meets the standard except for Q CELLS, Trina’s popular “honey” panel, Canadian Solar’s SmartDC panel, and Winaico panels.

[Update 7 March 2017:  Trina Honey panel datasheets now display certification for corrosion resistance and in the comments below Mars7 kindly provided a link to certification showing Winaico panel corrosion resistance.  In addition, Winaico themselves have chimed in to say all their panels are corrosion resistant despite it not being stated on their datasheets.  Clearly, just because a datasheet doesn’t say a panel is corrosion resistant doesn’t mean it isn’t.]

[Update 10th March 2017: Mars7 has provided links in the comments below to updated Canadian Solar SmartDC panel datasheets which shows they now state they are corrosion resistant.]

[Update 13th March 2017: I have contacted QCELLS and they have told me their panels are corrosion resistant.]

[Update 24th May 2020: Winaico have informed me their datasheets now state their panels are salt mist corrosion resistant and have provided me with a copy of their panels’ level 6 corrosion resistance certification.]

There could be other datasheets out there that don’t state they meet the standard, so be sure to check, just in case.  And if you live on the coast and are not using a tier one panel then it becomes vital to check.

Make sure an independent third party has determined the panel meets the standard and given it the certification to prove it.  If a panel’s datasheet just says, “Trust me, I’m corrosion resistant,” that promise isn’t likely to do you much good if it was made by a crap manufacturer producing panels in a workshop for the ethically challenged.

The Six Levels Of Corrosion Resistance

There are six levels of corrosion resistance to the IEC 61701 standard. Level 1 is suitable for marine environments such as on roofs by the beach.  Level 2 isn’t actually used, while levels 3 to 6 represent increasing levels of corrosion resistance.  To receive a level 6 rating panels have to survive 112 days of testing that simulates decades of exposure to a salty environment with less than 2% decline in power output.  That’s twice as long as the 56 days panels have to survive to get a level 5 rating.

If you want peace of mind you can get yourself a panel with level 6 resistance.  While they’re not quite suitable for use on submarines they should be able to handle any exposure that doesn’t require being submerged in salt water.  Technically level one resistance should be all that’s required for solar by the coast, but fortunately most panels that are certified have better than level one resistance, with level 6 resistance being very common, so you are unlikely to have to settle for the lowest level of protection.

The Danger Zone Is Within 200 Meters Of The Beach

In a reasonably sheltered area, such as near the beach in Adelaide or in Hervey Bay, there will rarely be salt mist more than 100m from the shore so you will probably be okay without corrosion resistant panels beyond that point.

In places where the weather and waves tend to be wilder then you’ll probably want to ensure your panels are corrosion resistant if they are going to be installed within 200m of the shore.

And if your town looks like this then you definitely need level 6 protection.

Warmth and humidity increase the rate at which corrosion occurs because salt only corrodes when it’s wet and heat speeds up any chemical reaction. So if you live in tropical Australia, such as in Darwin or Townsville, you’ll want to be absolutely certain your panels are salt resistant if there is any chance of sea spray reaching them. Especially in Townsville on account of how the sea is so friendly there it occasionally sloshes into the center of town just to say hi to everyone.

But don’t take my word for what is a safe distance. Check out your site and see if things such as fence posts, letter boxes, nails, air conditioner units, and so on show signs of excessive rust. If there are signs of above average corrosion you’ll want your panels to meet the standard for corrosion resistance.

If There Is Any Doubt, Go For Corrosion Resistance

Even if you are a good 300m back from the shore and you are pretty confident the location never receives any salt mist, I say you may as well go with corrosion resistant panels anyway. This is because I recommend using a tier one panel in the first place and since most of them are corrosion resistant, the premium you’ll have to pay to have peace of mind will either be very small or none at all.  So if you are going to use quality panels in the first place, you don’t have much to lose.

Which Parts Of  A Solar Panel Can Corrode?

Corrosion affects all metals. Well, all metals except gold.  Gold does not corrode under conditions normally found on this planet, so feel free to invite C3PO and Hedonismbot down to the beach for a swim.

The form of corrosion we are most familiar with is rust which results from the oxidation of iron and steel.

Other metals can also oxidize, including aluminium, which is what solar panel frames are made of. This normally occurs very slowly because when aluminium oxidizes it forms a protective layer that inhibits further corrosion. As a result you can own something like an aluminium ladder for decades without it noticeably deteriorating. Unless it is the aluminium ladder that I bought. That one deteriorated pretty damn quickly. I told the store that its “Maximum Weight 85 kg” warning should have been much more noticeable, but they didn’t pay any attention.  I tell you, they are going to be in so much trouble if I ever manage to fit through their doorway.

As exposure to the elements wears away aluminium’s protective outer layer, corrosion can move deeper inside the metal. This normally happens so slowly for solar panels in Australia it is rarely a problem, but salt mist, especially in a warm humid environment, can greatly accelerate the process.

Corrosion can also affect the electrical wires and contacts in the solar panel and its junction box. Unless of course they happen to be made of gold, which I admit is pretty unlikely, unless King Midas is currently working in solar panel manufacturing.

James Bond sees the harm a Goldfinger can do.

Marine Grade Aluminium Resists Corrosion

Pure aluminium is very good at resisting corrosion, but aluminium alloys tend to be considerably worse at it and aluminium is almost always alloyed with other materials because it makes it easier to work with. So the first thing solar panel manufacturers do to improve corrosion resistance is make the frames from a marine grade aluminium alloy which resist corrosion, such as good old 5086.

Anodizing Fights Fire With Fire

Panel manufacturers will also protect your frames from being oxidized by using an electric current to oxidize them first.  While this might sound crazy, there is a method to the madness. This process, called anodizing, forms a hard protective shell that resists being worn away and so protects the aluminium against further oxidization.

Because the oxidization of aluminium by the elements is a slow and boring version of what happens when aluminium is set on fire, I feel quite justified in saying that anodizing fights fire with fire.

Paint Works Fine

Paint – not only does it taste great, but it will protect the things it covers from corrosion for years.

Protection Of Wiring

Corrosion can also affect a panel’s wiring and electrical contacts and the main way this is prevented is to seal up the panel, junction box, and connectors so, hopefully, salt water never gets in.

What The Hell Is Ammonia Corrosion Resistance?

Right next to where they mention salt mist corrosion resistance, solar panel datasheets will usually boast they have, “Ammonia Corrosion Resistance”.  Whether or not this is something you need to worry about all depends on how often you pee on your solar panels.  If the answer is never, then you can probably get by without it.

Ammonia corrosion is normally only a problem for panels placed on farm buildings where there are a lot of animals and a whole heap of peeing going on.

For most people, provided they can refrain from peeing on them, panels that aren’t ammonia corrosion resistant should be fine. Just don’t put them in Uranus. Uranus, Jupiter, Saturn, in fact all the gas giant planets, have ammonia in their atmospheres.

Galvanic Corrosion

Corrosion from salty water blown in from the sea is not the only form of corrosion that can affect solar panels. Galvanic corrosion is also a potential threat. It occurs when two different metals come in contact with each other. In dry conditions it may not be a problem, but throw in some salty water and the more vulnerable of the two metals can quickly corrode. For example, if the aluminium frame of a solar panel comes in contact with any steel mounting hardware, corrosion will eat into the aluminium frame where the metals touch. In most of Australia this will happen very slowly but by the coast it could potentially cause panels to fail well within 10 years.

No competent installer will allow solar panel frames to come in direct contact with steel, but there are some incompetent cowboys out there and some of them even work for big installation companies. To avoid this problem I suggest using an installer recommended by SolarQuotes. I hear they’re very good at weeding out the shonks.

Solar Inverters And Corrosion

Solar inverters can also suffer from corrosion. High quality inverters are normally quite resistant to it, but in an area with heavy sea spray I’d recommend either placing them inside a cool garage or providing some form of shelter such as a hood or cabinet.

Cheaper inverters will be more likely to suffer from corrosion, but they’ll also be likely to fail earlier and so, on average, won’t have as much time to get corroded.  But it is probably still be a good idea to either install them inside or give them some kind of protection.

Solar Panels And Sea Grime

Corrosion isn’t the only problem panels installed by the sea can have. You may have noticed windows on buildings by the beach can rapidly become covered with a layer of gritty, yet delicious, salty grime. In some places it can be mixed with enough organic material to make a sticky biofilm, which is a mat of bacteria and not a movie genre.

This grime will stick to solar panels and reduce their output, although usually by well under 10 percent. Your options are to clean the panels regularly, or simply add a panel or two to cover the lost output. Remember you can safely add more panels than your inverter’s rating may otherwise suggest.

The Moral Of This Sea Shanty Is…

To sum up, if you think there is any chance at all your solar panels will suffer from sea salt corrosion, then get panels that meet the IEC 61701 standard for salt mist resistance because if you are installing quality panels anyway it is likely to cost you very little or nothing.

If you are in a location that does get a lot of salt spray, consider installing your inverter in a cool garage or providing it with some form of protection. Also consider adding an extra panel to your roof to make up for power lost due to salty grime on your panels.

And finally, don’t trust robots. Slowly, but surely, they are drawing their plans against us. I know, because that’s what I’ve programmed my robot to do.

Updated on 11th of September to add to the list of panels that do not have corrosion resistance certification on their datasheets.