Hi, it's tear down time. and yes, you voted for this one so we're going to tear it down. It's the uh Hoi Miles I Have been told that is the correct pronunciation Uh, they make solar inverters and uh, they very kindly sent in uh, this is the runt of the letter. this is a 400 watt.

um PV solar inverter. So it takes you a single solar panel uh, input anywhere from 16 to 60 volts there at Max input 65 volts. So basically a single panel and then it'll start up at uh, 22 volts and that'll give you 240 volts out. and uh, it's a 400 watt jobby.

so this is more powerful than the best one. Uh, that there's ones that I've got on my roof. I've got the 295 watt in phase one so this one leaves that in the dust because I've got left 370 watt panels or something I'm only using 295 watt micro inverter anyway I've done a video on that LinkedIn if you haven't seen it so we're going to get serious, we're going to get the gloves on because as you saw a snake oh God Okay, stuck back down. a sneak.

oh jeez, hang on Hey sneaky Peak that we got in the last video Jesus yeah it's really it stuck itself back down. it is fully potted anyway. it's a very uh, nice bit of Kit Physically look at the big heatsink on it this it looks like it is like they've got their own wireless system I Don't believe it's Wi-Fi I Think it's their own custom uh system? Don't quote me on that though. but uh yeah, it is actually filled with a re-enterable um, pot in gel.

I Guess it's not a hard potting compound, so what you can actually do is you can actually get in there with your screwdriver. You know, if you've got a pot in there, you can actually get in there and you can actually tweak it and when you pull it back out, it, oh, it's this one doesn't quite reseal. I've used re-entable uh, potting uh gels before that are truly like a re-enterable Anyway, these ones you can actually get back into them so we should in Theory be able to pull this out. so I don't know if you know the exact type.

Maybe I should ask them what is the exact type I'll I will actually ask them before. I Edit this video and see if they do get back to me very quickly. Um, oh geez, that's coming off pretty easy isn't it? Anyway, oh no, it's stuck in the inductor. Look at that.

Ah yeah. I mean you could shove it back in I Mean this is going to be thermally conductive stuff too. So of course to uh. But the whole idea is that it's completely weatherproofed because this is sitting on your roof under your solar panels even though it's protected.

Oh, there we go. there's a movel something. got to be careful that you don't rip up. Your Parts Anyway, there's the uh, looks like there's the wireless.

This is really fun. This is uh yeah yeah. I'm enjoying I'm enjoying this. Can't see the look on my face but oh yeah, this is good stuff.

Loving this. but yeah, it's going to be a uh DC to DC step up because you've got to convert the DC Ultimately, all this does essentially is convert um a DC voltage into 240 volts Ac. So it's like a, you know, just a regular, like a 12 volt car inverter thing. Except the voltage does vary and you want maximum PowerPoint tracking I assume that this is discharged I have not powered it up and uh, it would have been powered up maybe a long time ago in the factory.

So maybe I should actually be a bit more careful. I Don't want to set a bad example, but I'm pretty excited here. Is that a uh temperature sensor on top of that? Don't know. Anyway, I am shooting this in 4K resolution for those playing along at home.

Oh by the way, I forgot to show you the connections I don't recognize that? Is that a uh Hoy miles? um special. But anyway, you've got the standard Mc4 connectors here for your solar so it just plugs straight into your solar panel. Of course there's a big mounting Point here to mount on your uh, your frame on you that your solar panels are mounted on. This is fun stuff.

Really good. that's uh, thermally compound a thermal compound um I'm sure it's thermally conductive. We could probably test that. they do actually have a plug here which just pops out.

so I presume that uh, either you can extend the mains like that. um, so you can like plug them all in parallel. Yeah, this one's only got the one lead supplied. Um, because of course it's all on just one big uh Mains AC bus.

That's the advantage of these inverters is that it's relatively low. well, lower voltage than a traditional string inverter like mine at home. For example, with 12 panels is uh, 450 over 450 volts DC and that's going to ruin your day. And I've done a video on how that's one of the benefits of micro inverters is that uh, yeah, there's no high voltage DC Arc over.

So there's essentially no, you know issues with uh, fire of these things because if you've got a real high high voltage, high energy DC source and it arcs over as it does in those Um suite and those uh isolation switches, they catch on fire and a lot of homes have actually burnt down because of DC Solar DC isolation switches. and even here in Australia they've had to recall like dozens of different models. My one wasn't caught up in the recall, but you've seen I've done a video which I'll link in on the Folia Mine did actually fail, it didn't Arc over thankfully and burned down my house. That would have ruined my day anyway, even though these are still still present.

of course, the 240 volt AC risk. Um, and that's nowhere near as bad as the high voltage DC string. So the other thing is, depending on your country, um, a regular electrician can install these systems as opposed to a, you know, a certified solar person who's got to be certified for installing high voltage. um DC solar systems.

They can be installed by your regular electrician and to and still be uh compliant. so no worries. So who am I Always have single, Channel, dual, Channel and four channel jobbies of this as you've seen in my previous video and I'm absolutely sure that the two and four Channel units are exactly the same as this, except they've got extra channels so we'll just tear down the little runt of the letter here. Yeah, cheap ass gloves.

Well, there you have it. we're in. but uh, I don't see a sufficient number of switching transistors I Only see two down here. Um, and that's it.

So yeah, obviously we've got DC in here. Uh, these look like they're probably all in parallel and then we've got our high voltage DC to DC converter switcher here. so all the switch in mosfets must be on the bottom side here. I Was wondering what these little puppies were at first glance I thought oh, they're little trimmers, are they And then I went no, no, they're not little six pin jobbies.

And if you look at the silk screen actually, uh, TR they're actually a little uh, miniature Transformer is the micro which will also be on the bottom somewhere that actually has to measure the uh, not only the mains, but input to make sure that the voltage is there, but the frequency as well. Uh, because this thing has to automate by regulation, it has to be sold. Um, in this country. and I think pretty much any other country, it must, uh, switch off if it doesn't detect the main so that it doesn't backfeed.

So if there was a grid power fire, uh, over here, then you don't want this inverter pumping out voltage. Uh, to the um, the poor Oompa lumpas working on the transmission lines and they'll get zapped. So yeah, all uh, inverters and not only micro inverters, but like big string inverters? Um, yeah, must a disconnect from the grid unless they're specifically designed for off-grid use. And that particular safety feature is known as anti-islanding So if you hear that uh mentioned in or in the data sheets, then uh, yeah, you know that's what it's for.

It's a safety disconnect because there's you know, a lot of energy. Behind These Solar panels. Especially if you've got a big string system. Well, in this particular case, um, it doesn't matter because you'd have multiple ones.

and if this was, if there were power failed on your grid, over here, this thing was just pumping out. you know, kilowatts and then you have you know, hundreds of houses doing it on the same connection, then uh yeah. um, something's going to go bang somewhere or some poor Line work is going to get vaporized. Is that a lead on the bottom that shows through? I Don't know.

Um, it looks like it. Anyway, there's a heatsink, so most likely we've got uh, surface mount switching transistors under on the bottom side of this board are pressed against uh, the bottom of the case and that's what they're using is the heatsink. All right. So let's check these caps here and uh, see if they're in parallel.

I Can see that there I can see at least one pin is connected in parallel. So that's the positive. So yep, all the positives and all the negatives, let's have a squeeze. Yep, now is the negative actually connected through to solar negative? It is, indeed.

There's a couple of caps under there. Um, directly across. Actually, they've got a single cap across the input there. And of course, I've done videos on where those sort of caps have caught a light.

Now, if you get a micro crack in there and they fail short, there's a lot of energy in that solar panel that's going to release the Magic Smoke in that cap. So after Link in that video, problem here is I don't know how far that compound goes under though. I can actually move. Wiggle wiggle wiggle.

Yeah, the board from side to side so it's loosey-goosey but oh um, that feels like it's going to crack. Wow, No, it's just it's bending like here. Well, that's interesting. It looks like these two caps here are sit in a cutout in the PCB whereas these two caps over here don't.

They're a shy brand 105 degree jobbies. Um, yeah, they're all right. You know they're not a Panasonic, but there are, but they are a reputable name in China at least. Oh no, there you go.

They've got cutouts as well, but yeah, the board just doesn't extend out like that, so that's interesting. Anyway, they're doing that for the height profile. of course. these caps are the diameter of these.

These are too large to put them flat. flush on the PCB and then the top lid on here so they have to put the cut out in there. I Got it? I Got it? Um, yeah. it's completely.

Ah, power device is stuck right down to the bottom. Nope. it's just all thermal. It's it's Turtles all the way down.

See the imprint of the uh processor down there. look. Got some either. power transistors, power diodes, whatnot.

Um, yeah, you can see the pins, of course, the through-hole stuff. As I said, this is all thermally conductive. We might run a test on that. That's the whole idea and insulative of course.

Otherwise, you're going to come against her real quick. And of course, yeah, here's all the extra power transistors. I was expecting a whole bunch there. There you go Anyway, there's our main processor I'll take a high-res photo of this and the other side and then we can go over to the computer and uh, have a squeeze.

All right. So let's see if we can figure out what's going on here. I've got the top of the PCB like this and I've got the bottom which I have, uh, flipped around so all the electrons are gonna, um, go on one side. It's going to be very confusing.

So the DC input down here is going to line up with the DC input down here. No workers. So we have our negative and our positive DC input here. and then we go through an inductor like this.

We've got a little common mode. yeah, common mode joke. That's pretty how you're doing, isn't it? And we've got our Jtags over here now. what processor do we have? Well, you can't see it here.

Um, because or there's Gunk on all the chips. So I had to like ungunk them. It's actually a TMS 320 DSP old school. I'm the winner.

That's very surprising for a, uh, like a Chinese um, product like this. So yeah, but I haven't got some old school designer there? Yeah, TMS 320 No workers. So that's really interesting. Now, as I mentioned, uh, the input caps down here.

they're directly across there. so if that goes, uh, short circuit. Um, yeah. the magic smokes aren't going to escape it.

but these things aren't subjected to vibration and you know Flex stress and stuff like that so you know it's it's fine. And they've got the same thing here as well. They've got a cap. There's another one the there which is not fitted.

Now there's a current sense resistor here, so they've got a low side because this is a negative input here. they've got a low side current sense resistor and you can see the differential pair going off to obviously a low side current sense amplifier here. and that's going into our TMS 320. And obviously you can see here that all of the Caps are in parallel as we measured.

So yep, and we can go to the top side here and you'll get uh, the same thing. So this is the positive. Uh, this is not a ground plane. This is the positive plane so you can see all of those are connected in parallel.

So all these caps for 2700? Uh, Microfarad and the 63 volt is the dead giveaway. They're the input caps. Presumably they need the input. You know it's a DC Source right? But presumably they need those input caps because if Sun comes over fluctuations clouds Shadows you know, bird flies over or whatever then you don't want.

Uh, your processor. Actually, you know, just getting starved to voltage and being dropped out so it looks like that. Yeah, they need. That's where they needed.

All of their bulk storage is actually on the input. But interestingly, you can see here, there is no input fusing. It is directly across those caps. So um, yeah, you know, which is normally not a problem because the supplied Mc4 connectors, um, they're polarized right so you can't hook them up the wrong way.

But you're not counting for the human factor. You know Bruce is installing on the job and he goes, ah yeah, no worries, they're just down a couple of beers and and then I'll rewire this panel here and uh, she'll be right. No worries. and yeah, yeah, Kamagatsa.

So yeah, if you, uh, apply the Um panels backwards, um, that's going to go Banksy And as I mentioned before, we've got little uh Transformers here, which um, it's but interestingly, the three pins here look to be tied to the positive. So yeah, okay, um I'm not sure maybe the other yeah. I'm not sure how that's working, but um, TR is Transformer So I was going to say that's maybe for, uh, galvanically isolating the uh, negative input here. which is here, which is all these caps so it's actually marked there.

Um, so and it looks like the ground for the processor. that's all separate. You can see that here, so that looks to be galvanically don't know why you'd need to, but maybe is that galvanically isolated from the input here? Anyway, Yep. Uh, that little port on the back was leads.

There's there's two little leads in there which shine out the back. I Don't know who's ever going to see it I Guess during commissioning. Um, and that's about it. That's the only time you'll ever, um, see these things.

We're getting ahead of ourselves. but this is the voltage. These two resistors here. Um, they use big ass axial ones like this for the voltage.

Uh, standoff. And yeah, this is measuring the uh voltage on the AC Mains output. So they need to know that. So they need to measure the DC input and they need to measure the AC output.

So maybe is that coming from there? I'm not sure. or is that a Gate Drive for the switch in under the bottom here. I Don't know. I'm not really gonna like comprehensively reverse engineer this.

Aha, no. the bottom side here. You can see that there's our two axial resistors there and we've got that going over to here. So so obviously this, or at least this is the measurement part of measuring the mains output voltage.

so that will be detecting the mains voltage and the mains frequency. and if they aren't uh in compliance, Um, then if they're not there. if you get uh, you know, a grid fault, then that's part of the anti-islanding uh protection and that's all controlled by the micro over here. All right.

I've jumped ahead a bit and done a little bit of a reverse engineering here so we can figure out what's going on here now. Um, these are the mosfet switching transistors. We can have a look at these here. These are Aon 6250 Alpha Omega Job is 150 volt n-channel mosfet.

Pretty grunty little things. and it looks like that they have two of those in parallel on each side. Now they're all identical. There's no uh, P Channel or n-channel thing.

Why? Because there, it looks like that they're using an interleaved flyback here here. So they've got two different Transformers You can see here. they've got, well, two identical Transformers like this. So they're actually interleaving.

They're switching between this Transformer and this Transformer here. And then there's a these mosfets. They're in parallel and they're just uh, switching that down to ground here as you can see. So this is the positive input which is actually here.

but you know it's a bit hard to draw these things in situ. But uh yeah, there's the Uh primary side Transformer coil there and there's the secondary side on those pins there. So the reason that they're using interleaved fly bag here is probably no. Well, I when you interleave it with two Transformers Like this, you've instantly doubled your frequency for starters, so that makes it uh, more efficient.

And then you reduce your output Ripple current uh per given output capacitance as you can see on the top here that they haven't actually got much output capacitance. it's just these two caps here. basically. so I forgot to draw these lines coming out here, but this is basically um, a a boost DC to DC converter and interleaved flyback.

So you've got your, you know your 60 odd volts maximum coming from your solar panel input. Here, it's smoothed by these caps here, which, uh, holds it up just in case of any uh, brownouts or uh, you know, shading and then obviously this chip here, which I couldn't get details on I do actually have a number on that, but it's obviously like a dual mosfet driver. That's it just by its sheer placement there. and then the control lines run off.

uh, to your micro over here. So you, yeah, they're using two separate sides there to give an interleaved feedback and then, obviously, look, there's feedback. Come in here because the micro has to know the DSP right is controlling all of this actively. And if you have a look at the top side here, there's even more, right? There's another isolation.

Transformer Here, There's some more optocouply things here, right? So that micro on the bottom is like really controlling the it's you know it's it's measuring the outputs and it's optimizing everything. And then it's doing maximum PowerPoint uh tracking as well for the solar panels right? It's doing the whole kit and the caboodle. So anyway, 60 volts here and then you get a couple of hundred volts DC out of this and you can see that that's just diode out like that. they're just diode or like that and there's some.

As I said, there's a little bit of capacitance there. So low voltage DC Rail High voltage DC Rail Like this. and then they've just looks like they've just got a standard like H-bridge Uh, switch in here. There's is, uh, two mosfets here and there's two mosfets on the other side here and there's miscellaneous stuff.

and I won't get you know I Won't go into huge details, it's just a standard. Looks like a standard H Bridge uh. driver there and then you've got your main isolation. Um, the Transformer here which steps the high voltage DC up to AC here.

so you just switch that and bingo. They've got a relay here which is actually a pretty good one. It's a, you know Tycho there's no, like, no name Chinese stuff in here. Now we've got a big ass mob.

Uh, on the high voltage yard DC side here just in case. and um, yeah, this, the relay is a double pole. uh, double throw jobby. So this entirely disconnects it.

Um, from the grid here. So you've got not only isolation and they, of course, claim this in the data sheet. it's completely galvanically, uh, isolated. and um, yeah, it, it switches off.

Um, you know, part of the anti-islanding protection. All that, uh, sort of jazz. it physically, um, disconnects from the grid, so there's absolutely no chance of even if the switch in was still happening. On this side, that relay is disconnected over there.

So there will be an isolated relay drive going back to the main processor on here. In fact. I Haven't looked for that, but uh, that'd be it here. There you go.

there's your relay drive so that's going over here. Yep, so that that's your relay drive and that eventually must how somehow get back isolated to uh, the micro over here, which is controlling that. Then we've just got an output fuse here. Like this: we've got some output capacitance I didn't draw that in, but there's two extra caps here going down to uh Mains like chassis Mains Earth down here.

so uh, just for Emi uh purposes and we just got some extra filter in here. common mode? uh, choke. We've got another Uh cap on this side here. We've got a bleeder resistor here, so it discharges that um, you know, slowly so it's fairly safe.

Interestingly, there is another cap missing here I Don't know. was that for a higher power model or something? Got no idea. Anyway, Um, then we've got a dual mobs here I've drawn a single mold, but I think they might be uh in series. Haven't checked the exact uh connection there.

But yeah, so we've got big ass more uh, protection straight across uh, the mains. If that wasn't enough, then we've got a Gdt here. Here it is uh, 600 600 volt Joby and uh yeah, that's a Gdt that's a gas discharge tube so spark gap, uh, protection. And then we've got some another couple of caps there going down to uh one once again.

uh Mains Earth Down here you can see the green wire down there and they've got some bonus mob protection which I haven't drawn in here. In fact, I didn't look at that part I forgot to look at that look at that. it's like, um, it's what? Anyway, that's interesting, but yeah, they've got more protection down the ground so it's very well protected. So there it is.

um that? you know there's not a huge amount in this. so if this one can do 400 VA I'm not sure what um in phase are doing. for example seems to be a I Was contacted by and yet another micro inverter manufacturer and they wanted me to like review their micro inverters. so I you know, let me know in the comments down below if you want me to do another one to compare to this one I don't know um you know I've seen one Cinema I think but there you go.

Yeah, just a H-bridge driver galvanic isolation really switch in. We've got output filter in and that generates the mains and of course it's reading back uh via these. So for me, the major surprise is, uh, the TMS 320 uh processor here. They've got big capacitance on the input here which is not a fuse or a diode protected or anything.

anything going wrong? Yeah, but I don't know if. um, interleave? uh, flyback? Um, is typical in micro inverters like this I don't know if you know more, leave it in. comments down below: This is the first micro inverter I've torn down. So there you go.

Yeah, so in terms of um, isolation, they've got an isolation slot under here like this. um I don't know why they didn't extend the isolation slot on under here? I would have like. Just as a matter of course. although there's adequate, um, you know, creepage distance there.

But the problem with this is that if you get any, uh, moisture trapped, you know, due to the firm, you know, because these are subjected to Thermal extremes on your roof. So if you're getting the moisture Ingress or moisture buildup inside the thing, then you could actually get a uh, you know, leakage creepage path across here. But yeah, I don't know, you know. I I Think that clearance looks pretty decent.

So anyway, there you go that's inside a uh, Hoy Miles 400 VA 400 watt micro inverter I hope you found that interesting I certainly uh did I Don't know if I'd be able to power this up now. There was a bit a lot of bending on that board. so yeah, I don't know if this is still operational that stuff sticks really well on that potting compound. but uh yeah, that's interesting to tear down these things.

Absolutely fascinating. This is what uh goes into a I assume other micro inverters are, uh, typical. Maybe I should take up that other company on the offer and offered to do a uh tear down on there. Um I think 400 I know their ones go up to 500, as do the Um Hoi Miles ones.

I think they do a 500 watt model, but this is the Uh 401. so I don't know. slightly bigger, beefier output capacitance beefier Transformers You know, beefier switching perhaps? And don't forget to subscribe. You know what to do.

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If you did, please give it a big thumbs up. And as always discussed down below, catch you next time.