{"id":29704,"date":"2019-05-03T07:20:12","date_gmt":"2019-05-02T20:50:12","guid":{"rendered":"https:\/\/www.solarquotes.com.au\/blog\/?p=29704"},"modified":"2023-07-20T18:58:05","modified_gmt":"2023-07-20T08:28:05","slug":"72-cell-solar-panels","status":"publish","type":"post","link":"https:\/\/www.solarquotes.com.au\/blog\/72-cell-solar-panels\/","title":{"rendered":"Large 72 Cell Solar Panels Can Go On Home Roofs But Beware Of Shoddy Installers"},"content":{"rendered":"
\"72

Large 72 Cell Solar Panels Can Go On Home Roofs But They Must Be Clamped Correctly<\/p><\/div>\n

This article is about big solar panels.\u00a0 Bigger than the standard sized 60 cell panels commonly installed on residential roofs.\u00a0 Those are only around 1m by 1.65m.\u00a0 I’m talking about larger ones with 72 cells that are about 1m by 2m.\u00a0 These larger panels are mostly used for commercial installations and solar farms, but they can be used on household roofs provided they are installed properly.<\/p>\n

Unfortunately, this doesn’t always happen.<\/p>\n

One problem with larger solar panels is the clamps holding them aren’t always placed correctly.\u00a0 When the proper clamping zones<\/a> aren’t used it generally voids manufacturer warranties as they can suffer damage from being flexed by the wind.<\/p>\n

I’ll go over the main disadvantages of larger panels and I’ll cover their one potential advantage, which is cost.\u00a0 I’ll also explain why you should be cautious when it comes to getting a low cost 72 cell solar panel system installed.<\/p>\n

What I won’t do is spend much time explaining what larger panels are.\u00a0 They’re just 20% bigger than usual.\u00a0 It’s nothing particularly complex.\u00a0 It’s not like the question of why does stale bread get hard but stale biscuits go soft.1<\/a><\/sup><\/p>\n

Half Cut 144 Cell Panels Are Similar To 72 Cell Panels<\/h2>\n

Half cut solar panels<\/a> are becoming popular.\u00a0 These have their solar cells cut in half to provide a small increase in efficiency.\u00a0 A 144 cell panel is simply a 72 cell one with its solar cells cut in half.\u00a0 Everything in this article about 72 cell solar panels\u00a0 also applies to half cut 144 cell models as they are similar in size and weight, with only slightly different average performance.<\/p>\n

3 Disadvantages Of 72 Cell Panels<\/h2>\n

Larger 72 cell solar panels are rarely used for home installations due to three main drawbacks:<\/p>\n

    \n
  1. They’re larger, so it’s harder to arrange panels to fit on a section of roof.<\/li>\n
  2. They’re heavier, so they’re harder to carry and haul onto roofs and safely install.<\/li>\n
  3. Clamping zones<\/a> — the locations where the clamps have to go to secure them to the roof — can be different from standard sized solar panels, making them more difficult to install correctly.<\/li>\n<\/ol>\n

    Big Panels On Little Roof Can Be Big Problem<\/h2>\n

    Smaller solar panels can cover more roof area. \u00a0If solar panels were the size of mobile phones it would be easy to cover an entire section of roof with hardly any dead space left over.\u00a0 In practice, with standard sized 60 cell panels, it is often impossible not to leave a lot of empty room around the edges.\u00a0 With larger moduels this problem is more pronounced.\u00a0 As a result, a system that uses 72 cell panels can end up with less capacity than if 60 cell modules had been used.<\/p>\n

    \"\"

    While the problem is not always so extreme, this diagram shows how it’s possible for a section of roof to support 250% more module capacity when standard sized 60 cell panels are used.\u00a0 (It may be hard to see, but the panel on the right is 20% larger.)<\/p><\/div>\n

    Heavier Solar Panels Are Harder On Installers<\/h2>\n

    There are various methods for getting solar panels onto roofs but most of the time muscle power is used.\u00a0 And muscles, as well as the joints and ligaments they are attached to, can really start to hurt after lugging a dozen or so panels up onto a roof.\u00a0 A typical 60 cell panel weighs around 19kg while a 72 cell module is around 22.5kg.\u00a0 That may not sound like a big difference, but when hauling them onto a roof it’s definitely noticeable.\u00a0 Larger solar panels also catch the wind more, making them unwieldly and harder to handle.\u00a0 This is clearly dangerous when up on a roof.<\/p>\n

    \"\"

    “This isn’t unwieldly!\u00a0 I install 72 cell solar panels for a living!”<\/p><\/div>\n

    While using larger panels means fewer need to be carried in total, from the point of view of strains and injuries, it is generally safer to make more trips with lighter loads than fewer trips with heavier loads.<\/p>\n

    The extra weight of 72 cell panels is not a problem for the roof, as it gets spread out over a similar area as when 60 cell modules are used.<\/p>\n

    Panel Clamping Zones Can Be A Problem<\/h2>\n

    A major drawback of some 72 cell solar panels — their main weakness, their Achilles’ heel, if you will<\/a> — is their clamping zones can be very different from 60 cell panels.\u00a0 Many can only be clamped on their long sides and some have very small clamping zones that leave little margin for error.\u00a0 The smaller the zones and the less motivated an installer is to do quality work, the more likely you are to end up with clamps outside the correct zones.<\/p>\n

    Under Australian consumer law the installer is required to fix problems caused by their incorrect clamping, but if the installer has disappeared and the manufacturer’s clamping recommendations weren’t followed, the manufacturer is likely to declare their warranties don’t apply.<\/p>\n

    Using Installation Manuals To Find Clamping Zones<\/h2>\n

    To find out the clamping zones of a module you will need to check its installation manual.\u00a0 These can normally be downloaded from the solar panel manufacturer’s website.\u00a0 JinkoSolar<\/a> is the world’s largest producer of solar panels and many of theirs are on Australian rooftops, so I will use them as an example of how to check clamping zones.<\/p>\n

    First I went to the Jinko Australian site<\/a> to download their installation manual but the links weren’t working, so I instead found an older version online which was full of useful advice such as:<\/p>\n

    \"JinkoSolar

    Remember, always avoid anything that could threat your safety.<\/p><\/div>\n

    Then I checked their site again and found it was working properly.\u00a0 So I went to this page and was given a choice between a UL<\/a> user manual and a TUV<\/a> user manual.\u00a0 UL is an American standards organization while TUV is a German one and relevant for Australia.\u00a0 (Let’s face it, Germans tend to be better at these kinds of things.)\u00a0 So I downloaded an up-to-date installation manual with better English and found the following information on clamping zones:<\/p>\n

    \"JinkoSolar<\/p>\n

    In the table above the 72 cell panels are in Groups 5, 6, 7, and 8.\u00a0 To work out the clamping zones you have to look at the J and K figures and there are two sets of them.\u00a0 One is for 5400 Pa<\/a> and the other is for 2400 Pa.\u00a0 These are measures of how much wind pressure the modules can withstand and in Australia you will want the clamping zones for 5,400 Pa.\u00a0 The clamping zone is equal to the J figure subtracted from the K figure, which makes them 200mm or 20cm which is 10% the length of the module.\u00a0 This better than the clamping zones of their 60 cell panels that are only 14cm or 8% the panel’s length.<\/p>\n

    REC Solar Has Small 72 Cell Clamping Zones<\/h2>\n

    Here is a diagram showing the clamping zones of a 72 cell REC Peak Energy solar panel:<\/p>\n

    \"REC<\/p>\n

    Its clamping zones are only 10cm across, which is only 5% the length of the panel.\u00a0 This is less than half the length of the 20cm clamping zones on their standard sized panels.\u00a0 This leaves very little room for error and an installer will really have to be on top of things to ensure they are installed correctly.<\/p>\n

    Trina Panel Clamping Zones Larger Than Most<\/h2>\n

    I downloaded Trina Solar’s installation manual from their Australian site, but it only gave information for clamping zones for 2,400 Pa of wind pressure when you want them to be clamped for 5,400 Pa.\u00a0 So I looked online and found a different Trina installation manual with this diagram:<\/p>\n

    \"Trina<\/p>\n

    The writing is a little small but it says to withstand 5,400 Pa of positive (downwards) wind pressure the clamps have to be located on its long sides between one eighth to one quarter the distance from the corner.\u00a0 This makes the clamping zones for their 72 cell panels 24.5cm, which is 12.5% the module’s length.<\/p>\n

    Canadian Solar Recommends 6 Clamps<\/h2>\n

    Here’s a diagram from the Canadian Solar installation manual that recommends 3 roof mounting rails and 6 clamps be used for their large CS1U-MS panel:<\/p>\n

    \"Canadian<\/p>\n

    When 6 clamps are used the clamping zones are 10cm, which is 5% the length of the panel.\u00a0 Four clamps will suffice but the clamping zones are only 8cm across, which is 4% the length of the panel.\u00a0 This allows even less margin for error than REC 72 cell solar panels.<\/p>\n

    The Best Clamping Zones Should Always Be Used<\/h2>\n

    Some solar panels give a choice between clamping zones that are suitable for high wind and lower wind locations.\u00a0 In Australia the highest wind clamping zones should always be used.\u00a0 Even if you live in a low wind area you never know when giant willy willy might come through and cock things up.2<\/a><\/sup><\/p>\n

    Voltage Issues<\/h2>\n

    Standard sized 60 cell solar panels are usually rated for up to 1,000 volts while most 72 cell panels are rated for 1,500 volts.\u00a0 But in Australia the highest voltage allowed for residential solar is 600 volts, so it should make no difference for home solar power — provided they are installed correctly.<\/p>\n

    Unfortunately, shoddy installers sometimes don’t allow for larger panels having higher wattage ratings and install them as though they were they were standard sized solar modules.\u00a0 This can result in the system’s DC voltage exceeding Australian standards and the inverter’s limits, potentially creating a dangerous situation.<\/p>\n

    Their One Potential Advantage — Cost<\/h2>\n

    There is only one potential advantage to using 72 cell solar panels and that is money.<\/p>\n