Solar Panel Testing Has Moved On. Has Your Tester? - PV Checks One

[00:00:00]There's an unwritten rule I've discovered with solar PV testing. The moment I say the words solar tester, the clouds gather, the rain starts, and summer quietly leaves the country. I need to know, is this just me, or does your solar test kit also come with built-in weather control? Let me know in the comments. I even flew to Italy to collect this new PV-Checks One directly from the manufacturer, thinking sunshine might finally break the curse. No chance. The demo finished, and guess what? It rained.

[00:00:26]>> [snorts] >> One month later, I'm finally back to put this thing through its paces. And yes, it does come with a sundial in the box, presumably so you know what perfect testing weather is supposed to look like. Of course, it's not just the weather that can catch you out with solar PV testing. The panels themselves are changing. Modules are getting physically larger, power ratings are climbing, and bifacial panels can generate from both sides. But manufacturers can't just keep winding up the voltage, because once you start moving beyond 1,000 V DC, the world gets more complicated. Different equipment, different design considerations, different training requirements, and a bigger regulatory headache. So, for many installers, keeping PV systems below that 1,000 V DC line still matters, which means a lot of the extra power from modern panels is arriving in a different form. Current, more cell area, half-cut designs, parallel path through the module, and rear-side generation from bifacial panels all add up to higher amps. That's good news for energy yield, but it can be bad news for testing. Because if the PV installation has moved on, the test equipment has to move on with it. Thankfully, this new PV-Checks One is designed for that shift. It can handle PV string currents up to 30 amps, which makes it a good fit for the kind of residential and small commercial systems installers are now seeing more often. But higher current is only one part of the story. There's another increasingly common feature on modern solar installations that can make testing more awkward. Module-level power electronics, optimizers, rapid shutdown devices, and other electronics fitted at panel level can all change how a PV string behaves when you come to test it.

[00:02:07]So, the question is not just whether a tester can cope with higher current, it's whether it can cope with the electronics now sitting between the panels and the inverter. And that is where this tester starts to get interesting. Because this is where the PV-Check 1 claims to be a first. It's designed to safely perform insulation resistance tests on solar PV strings with module-level power electronics still connected in the string. That matters because normally devices such as optimizers, rapid shutdown units can complicate insulation resistance testing. In some cases, the safe answer is to remove them from the circuit before carrying out the test, but that takes time. And on a roof with a lot of modules, that turns what should be a straightforward DC wiring check into a connector opening treasure hunt. With PV-Check 1, the idea is that you can check the integrity of the DC wiring without having to remove those module-level power electronic devices from the string. So, here in the plant room, we're going to perform the insulation resistance test on the arrays that are connected to this Huawei inverter. Few important points: one array has optimizers, the other one doesn't. It's important not to mix the tests up and do the wrong one on the wrong array. An easy way to check, obviously, on the conventional array, you'll see a high voltage, which you can check using the multimeter function built into check one. The other one, for the Huawei one with the optimizers fitted, they give out a resistance on the array of 1 k ohm per module fitted.

[00:03:35]So, the 17 optimizers on there, we'll measure that with a conventional multimeter, you'd expect to see 17 k ohms. So, that's how you know you've got the right array. It's a simple process to do the testing, just selecting the right one in the menus. Of course, another challenge when you're working at the inverter. You need to disconnect the DC strings from the inverter itself if you're performing on an installation that's already been installed so maintenance work. Need to ensure there's no current flowing in those cables before disconnecting the MC4 connectors.

[00:04:06]Now, you usually do that by turning off the inverter's built-in switch right here underneath the unit. If you don't do that and current's flowing, when you pull those out, you'll draw an enormous arc. Obviously, that can cause serious burns and the other one, it will destroy the connectors on the inverter, which is a tricky repair job. Now, one way to make sure that isolator has done its job and the same with any other external isolator is to use the TIS 9000 open jaw clamp meter. Now, we reviewed that in another video. I would recommend checking that out cuz it's a great bit of kit for anyone that's regularly working on solar systems and it can also be used to do that resistance check to check how many optimizers are connected to this circuit. So, we're going to get this array powered back up and hopefully everything is working as planned. On this installation, it's a pass but back at the HT Instruments test facility, the team showed me what happens when there is an insulation fault and how the PV-1 can detect it on a string fitted with module level power electronics. And that's the key point here. This isn't a standard insulation resistance test.

[00:05:16]It's a dedicated test mode for checking the integrity of the DC wiring on strings with optimizers, rapid shutdown devices or other module level power electronics still connected.

[00:05:27]And we followed the journey of the PV check through various iterations as the product keeps improving with each generation. One thing that is constant though, you do need a reasonable amount of sunlight for the tests to work.

[00:05:39]Something that often eludes me no matter where we are in the world to try and produce the video. So, we're out here.

[00:05:46]We're going to do now the IVCK test.

[00:05:49]It's an important test to do because it proves lots of things. It proves that the panels are working as the manufacturer intended. It proves you've got enough of them in the right string configurations. You haven't mixed them up. And it also checks whether you've made any wiring mistakes in terms of polarity. Perhaps somebody's just nicked a cable as they're trying to undo the cable ties that the manufacturer has put on the leads that come with the panels.

[00:06:09]Simple process. Connect up to the strings. Connect to the grounding system if there's one in place for the array.

[00:06:15]We've got a local earth rod here. And then we need to couple in the light sensor and the temperature sensor, which is a remote unit. So, we don't need to wire that into this directly. It works off Bluetooth. That would have been a bit of a struggle back in the plant room because underground Bluetooth's not so clever. There is a way around it that we did look at in a previous video.

[00:06:33]However, we're close by here and it is almost perfect conditions. We've got the sort of light level you'd expect to get data sheet values up at nearly 1,000 W per meter squared. So, we set the test push the button, and it steps through all of those tests and you get a result within about a minute for the whole array. And that's job done. We're not going to turn this video into a full tour of every test function because we've already covered some of the key ones. If you want to see the full IVCK test process, check out our video on the previous version of this tester. The interface on the PV1 is the same. So, that walk-through still takes you through the process. There's also a ground fault locator built into this unit, which is really useful when you're trying to track down where an insulation fault is hiding within the array. We've covered that process in a separate step-by-step video as well. But back then, it was a separate unit. Now, it's built in to the PV1. And it sounds like this tester may continue to gain new functions through future firmware updates. So, make sure you subscribe because when those updates land, we'll take you on a proper look. One issue we haven't covered in great detail before is bifacial panels and the clue is in the name. They can generate power from both sides. This makes testing a little more challenging because you're no longer dealing with the light falling directly onto the front of the module.

[00:07:55]With a bifacial panel, reflected light can also bounce back from the roof surface, mounting surface, or ground beneath the array, creating additional generation from the rear of the panel.

[00:08:05]So, if you want the test results to mean anything, you need to understand what the module is actually being exposed to, not just front-side irradiance, rear-side irradiance as well. To capture that, the remote unit for the PV checks 1 has three photo cell inputs. One photo cell measures the light hitting the front of the panel and two additional photo cells can be positioned behind the module, typically at higher and lower points on the array, but irradiance is only half the story. To perform the calculations, the tester also needs to know the manufacturer's module performance data. It can then work out what the panel should be producing under the actual test conditions. Those panel specifications can be stored in the tester memory and when you add a bifacial module, the key extra value is the bifacial coefficient. This tells the tester how much energy in theory the rear surface can generate compared with the front surface. Using the front and rear irradiance readings, the stored manufacturer's panel data, and the bifacial coefficient, the tester can account for contribution from both sides of the module and compare the measured electrical values against the expected design values.

[00:09:15]So, from rain in Italy to glorious sunshine here in Skipton.

[00:09:18]>> One month earlier.

[00:09:24]>> I'm actually testing the panels that Rick and Ross installed last year that we've just connected up to this inverter here. Few challenges in that. Can't get back on the roof. The scaffolding is long gone. So, I've set this bin up at exactly the right angle of the roof.

[00:09:36]I've got the irradiance meter, the remote unit there plugged in with the photo cell there. Can't get a temperature measurement from the panels up there, but luckily in the PV1 checks one you can do a manual input for the temperature. So, I've measured the temperature of some panels that we've got in the yard in this glorious sun.

[00:09:51]Hopefully, we'll get a good result.

[00:10:00]And good news, it's a pass, which is a relief because Rick and Ross put those panels up there quite some time ago. PV1 checks one is a great tool for all kinds of fault finding and of course compliance testing on solar installations. I was actually surprised that we got a pass there because there is a problem on this installation that you can find out in the next video where we install this Hyena hybrid inverter system. I'll leave a link in the description so you can learn more about the PV1 checks. It would be great to get your comments and questions for future videos.

[00:10:29]if you're out there testing installations that are fit with optimizers or rapid shutdown devices.

[00:10:34]And I spoke to someone recently at a trade show from the insurance industry and they are seeing a lot of problems with those modules in terms of reliability, potential causes of fire where I guess an instrument like this could be particularly useful to make sure they are okay. But, are you seeing that? Let me know in the comments.