{"id":21899,"date":"2018-06-25T14:55:48","date_gmt":"2018-06-25T04:25:48","guid":{"rendered":"https:\/\/www.solarquotes.com.au\/blog\/?p=21899"},"modified":"2024-01-25T10:33:59","modified_gmt":"2024-01-25T01:03:59","slug":"dnv-gl-2018-solar-panel-test","status":"publish","type":"post","link":"https:\/\/www.solarquotes.com.au\/blog\/dnv-gl-2018-solar-panel-test\/","title":{"rendered":"DNV-GL’s 2018 Scorecard Results — Longi, REC, & Suntech Only Residential Solar Panels To Pass All Tests"},"content":{"rendered":"
\"DNV-GL

Those nice people at DNV-GL have done another year’s worth of panel torture testing. Here is a summary of the results.<\/p><\/div>\n

Over the past 4 years the Norwegian company, DNV-GL<\/a>, has performed annual tests on solar panels and released a report on their performance.\u00a0 Their latest one, the 2018 PV Module Reliability Scorecard<\/strong> is now available<\/a>.\u00a0 The good news is solar panel reliability looks as though it is continuing to improve.\u00a0 If you buy now you are more likely than ever to get panels that will last for decades without failing and with only minimal deterioration in output.<\/p>\n

But note DNV-GL don’t test every panel in the world.\u00a0 Only ones they are paid to and makers of el cheapo1<\/a><\/sup> panels aren’t likely to shell out to have theirs assessed.\u00a0 So the improved quality may only apply to better manufacturers such as those that are tier one<\/a> or otherwise have good reputations<\/a>.<\/p>\n

If you like, you can read what I wrote about last year’s<\/a> report or the year before that<\/a>.\u00a0 But keep reading this article and I’ll tell you about the 4 tests used for their latest scorecard report and which panels earned DNV-GL’s “top performer” status for each.\u00a0 I’ll also let you know which 3 panels suitable for rooftop solar installation passed all their tests this year2<\/a><\/sup>.\u00a0 I’ll also point out that just because a panel isn’t a top performer doesn’t mean it’s not good quality.\u00a0 This is because DNV-GL doesn’t tell us whose solar panels were submitted for testing or which ones failed.\u00a0 They only tell us about those that did well.\u00a0 While this a very positive and upbeat approach it does mean their scorecards aren’t as useful as they could be.\u00a0 I suspect you may have to be a paying customer to get all the dirt.\u00a0 But only knowing which panels did well is still useful information and I’m very thankful it’s freely provided.<\/p>\n

DNV-GL Is All About Standards<\/h2>\n

DNV-GL is a standards organization.\u00a0 By this I don’t mean they won’t let you put your elbows on the dinner table or scratch your head with a fork. The kind of standards I’m referring to are certifications that show a company’s products meets certain standards.\u00a0 While they don’t certify everything, they can help you out with a wide range of items ranging from mining and oil extraction equipment to solar panels.<\/p>\n

If you want a piece of paper that says your solar panel meets the minimum standards required to be sold in a sensible country, DNV-GL can help you out.\u00a0 And if you want to see if you have a quality solar panel that a home or business can confidently buy without worrying about it failing or suffering more than mild deterioration, then you can subject it to the kick-arse testing DNV-GL uses for its scorecard reports.<\/p>\n

They Only Give The Winners — Not Losers Or No Shows<\/h2>\n

DNV-GL’s Scorecard only gives the names of what they call “top performers”.\u00a0 These are the solar panels that suffer no more than 2% deterioration in output after testing.\u00a0 And it’s “pass or fail”.\u00a0 They don’t tell us which of their top performers did the best.<\/p>\n

I find this unfortunate.\u00a0 Maybe it doesn’t say much for human nature, but the gossip we regard as the juiciest and are most eager to hear is usually about miserable failure rather than excellent performance.\u00a0 So it’s a bit of a bummer we don’t get to learn about the solar panels that crash and burn.\u00a0 After all, it would be good to know what to avoid.<\/p>\n

We’re also not told if a particular panel that isn’t among the top performers was tested or not.\u00a0 So when we look at their top performers we can only know that those panels did well in the test, but we can’t conclude anything about panels that aren’t top performers because we have no way of knowing they were actually tested.<\/p>\n

Bills Of Materials Are Important<\/h2>\n

DNV-GL doesn’t just test one solar panel and base their conclusions on that.\u00a0 They test multiple panels and average the results.\u00a0 This is important because panels that appear identical and have the same model number can have considerable differences in durability.\u00a0 Some of the variation is because there is always some imprecision in manufacturing, but it mostly results from using materials of varying quality.\u00a0 The exact list of specific components used to make a solar panel is called its Bill Of Materials or BOM.\u00a0 Just one small alteration to its BOM can make a panel’s performance go from fine to awful.<\/p>\n

The illustration below is an example DNV-GL gives that shows how a single change in the glue that holds solar panels together3<\/a><\/sup> can make a huge difference in performance on their Potential Induced Degradation or PID test.:<\/p>\n

\"Balance

Image: DNV-GL<\/p><\/div>\n

While both solar panels suffer very little harm after the first 96 hours of testing, the one with the high quality glue is still doing well after an additional 96 hours while the one with lower quality glue has suffered six times the deterioration.<\/p>\n

Homeowners Can’t Do Much About BOMs<\/h2>\n

Unfortunately, if you are looking for solar panels for your home<\/a> there is not much you can realistically do about Bills Of Materials.\u00a0 But solar installers and wholesalers can check whether they are getting the good stuff or if manufacturers are unloading their worst panels on we poor, trusting, innocent Australians.<\/p>\n

But average Australians can protect themselves by making sure their solar panels are tier one or from a manufacturer with a good reputation for quality.\u00a0 While this won’t guarantee getting panels with the best BOMs it does help as these companies generally want to build up a good reputation and hopefully are aware of Australia’s consumer protection laws and don’t want to fall afoul of them.<\/p>\n

The Four Tests<\/h2>\n

This year DNV-GL gave solar panels 4 different tough tests for their scorecard report.\u00a0 They are listed in the table below4<\/a><\/sup>:<\/p>\n

\"DNV-GL

Image: DNV-GL<\/p><\/div>\n

The very best solar panel or panels in each test suffered no detectable deterioration at all, while those declining in output by 2% or less were called a top performer by DNV-GL.\u00a0 For each of the tests the majority of panels submitted were rated as top performers.\u00a0 While this doesn’t make it seem like a very exclusive group it is still a good result as the tests are rigorous and I regard it as good evidence that solar panel quality is improving, even if it’s not possible to conclude that for certain from the report.<\/p>\n

In general, the bottom results are less bottomy than in previous years.\u00a0 But while it is difficult to make a panel durable enough so it only suffers 2% or less deterioration after tough testing, it is actually very easy to simply not submit a crap panel for testing, so there is no good evidence that buying cheap panels<\/a> with zero reputation is any less of a bad idea than it was a year ago.<\/p>\n

Thermal Cycling<\/h2>\n

Stuff expands when it gets hot and contracts when it gets cold.\u00a0 Because different materials do this at different rates it places joins between them under stress, which can slowly degrade a panel’s performance.\u00a0 One effect is the weakening of solder joints between electrical connections that increases resistance5<\/a><\/sup>.\u00a0 This can result in a panel operating normally under low light conditions, but under good conditions maximum output will be reduced.<\/p>\n

In the outback, a solar panel can hit 65 degrees on a hot day and drop down to 15 degrees at night making for 50 degree temperature change over 24 hours. \u00a0 Daily temperature swings aren’t so extreme near the coast, so a good result on this test is more important inland.<\/p>\n

The test involves cooling a panel down to negative 40 degrees and then heating it to 85 degrees.\u00a0 While the temperature is increased it receives the maximum current it is rated for.\u00a0 This is done 600 times.\u00a0 And if you think that sounds tough, next year DNV-GL will crank it all the way up to 11<\/a>, which in Norwegian means 800 times.<\/p>\n

All the solar panels that suffered 2% or less reduction in output were classed as top performers and are displayed in the table below.\u00a0 The xxx in the model designations represents a panel’s wattage.\u00a0 Because this figure can vary a triple x is given instead of a number.\u00a0 Note not all the panels may be available in Australia6<\/a><\/sup>:<\/p>\n

\"2018

Image: DNV-GL<\/p><\/div>\n

A total of 44 different solar panels were tested and 8 of them were awesome and suffered no measurable decline in output, while a total of 34 passed.\u00a0 The number of panels in the chart above seem to match up with these figures, but it’s difficult to tell, as sometimes they put more than one panel on a line.<\/p>\n

With 77% of the panels passing and becoming top performers it’s not surprising they are planning to make the test tougher next year.\u00a0 They’re definitely not complacent in Oslo or sitting on their laurels in Bergen7<\/a><\/sup>.<\/p>\n

The Damp Heat Test<\/h2>\n

The second test was damp heat.\u00a0 Passing this is important for solar panels installed in places where it’s hot and sticky. \u00a0Heat and humidity can damage panels and even cause the glue that holds them together to become unstuck.\u00a0 This can result in poorly made panels literally falling apart.<\/p>\n

The test is done by putting the test subjects in a chamber where they are held at 85 degrees and 85% humidity for 2,000 hours.\u00a0 This was done to 52 different solar panels and 27 passed and became top performers with less than 2% decline in output:<\/p>\n

\"2018

Image: DNV-GL<\/p><\/div>\n

Only a single panel was awesome enough to suffer no measurable deterioration, but out of the 52 were tested 52% did well and passed.\u00a0 The worst performing panel had its output fall by a little over 8% which is not so bad considering that in previous years they had solar panels deteriorate by over 50%.<\/p>\n

Dynamic Mechanical Load Test<\/h2>\n

Wind and — in places that mostly aren’t in Australia — snow can stress panels.\u00a0 A stiff wind can cause them to continuously flex and gradually deteriorate.\u00a0 The dynamic mechanical load test simulates this by flexing a solar panel 1,000 times and then subjecting it to 50 thermal cycles as in the thermal cycling test.\u00a0 After that they put it in humid air and freeze it 30 times to allow ice to form in any cracks that may have formed and further damage the panel.\u00a0 This is 20 freeze cycles more than in previous years.<\/p>\n

After all this punishment, out of the 51 panels that were tested, 5 were awesome and had no noticeable deterioration while a total of 42 were top performers with less than 2% decline in output:<\/p>\n

\"2018

Image: DNV-GL<\/p><\/div>\n

No Humidity Freeze Test<\/h2>\n

The humidity freeze test simulates damage caused by temperatures falling below freezing in damp conditions, but DNV-GL skipped it this year.\u00a0 I don’t know why.\u00a0 Maybe there wasn’t room in their freezer because they’d smuggled too many Swedish meatballs across the border.\u00a0 More likely they thought the results of the dynamic mechanical load were similar enough, particularly after increasing the freeze cycles from 10 to 30.\u00a0 The good news is this was the least relevant test for Australians.\u00a0 If frosty damp was an Olympic sport we wouldn’t even qualify.<\/p>\n

The PID Test<\/h2>\n

Potential Induced Degradation, or PID for short, is a type of damage caused to solar panels by stray currents going where they are not supposed to, which is very naughty of them.\u00a0 It can result in marks on solar panels that resemble snail trails and in severe cases cause panels to completely fail.\u00a0 The effect is worse in warm climates with high humidity, so being resistant to this type of damage is very important in the tropics.<\/p>\n

The solar panel is placed under conditions similar to the damp heat test for two sessions that total 192 hours, while 1,000 volts are passed through most panels or 1,500 volts for larger 72 cell panels.\u00a0 Out of the 46 solar panels tested, 5 were awesome with no measurable deterioration while 27 were top performers with 2% or less decrease in output:<\/p>\n

\"2018

Image: DNV-GL<\/p><\/div>\n

Only 3 Residential Panels Passed All 4 Tests<\/h2>\n

There were a total of 12 manufacturers that had one solar panel model pass all 4 tests:<\/p>\n