EEVblog 1518 - Hoymiles Solar Microinverter TEARDOWN
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- Опубліковано 1 лип 2024
- Depotting, teardown, and some reverse engineering schematic analysis of the 400W Hoymiles solar microinverter.
www.hoymiles.com/products/mic...
CORRECTIONS: • Hoymiles Microinverter...
Hoymiles vs Enphase microinverter review: www.mcelectrical.com.au/hoymi...
Forum: www.eevblog.com/forum/blog/ee...
00:00 - Hoymiles 400W Micro Inverter
01:05 - Removing the silicone thermal potting compound
04:20 - Mains wiring and dangers of high voltage DC string inverters
05:43 - Installation requirements. Electrican vs solar installer
06:40 - PCB top side
07:54 - Anti-islanding safety feature
09:56 - What's a bit of flex...
10:48 - Bottom the PCB
11:41 - Reverse engineering time
15:57 - Mains voltage and frequency detection
17:03 - Schematic
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CORRECTIONS to the reverse engineering as pointed out by some viewers. The mains side isolation transformer is a common mode filter inductor: ua-cam.com/video/yOJ7xPugsdc/v-deo.html
Just about t say.... Way too small for a 50Hz part.
The common mode filter almost certainly functions somewhat as a differential inductor, too.
The isolation is done by the two-phase DC/DC boost stage transformers, which are modulated to produce the required wave shape; the H-bridge output transistors probably just serve as a polarity switch, as there's minimal capacitance on the output of the DC/DC boost circuit.
@@davidbeard7262 the isolation is provided by the AC coupling capacitors, so it can't affect the bias voltage on the transistors' base
At least that's what the book says
what about using a solar panel and a motor to turn an induction motor, a mind mill thing..
☀️🧲🤷♂️🙇♂️
@@DonaldSleightholme why would you ever do a dumb thing like that?
Really interesting! I would love a teardown of a different micro inverter! I always think you can learn quite a lot when you compare two different products and check what the two manufactures did similiar and where they differ. That's the interesting part! :D
Those little transformers TR100 and TR101 are actually current transformers to measure the current in the respective switching MOSFET and winding.
The current passes through the metal strip over the top of the ferrite core ( primary winding with 1 turn) and inside the core is the secondary winding with e.g. 100 turns. The sec winding is accessible on the two outermost pins on the left side. all the remaining Pins are NC and soldered just for mechanical stability.
Ah, yes, that makes sense. Should have gone in for the microscope closeup.
got P/N?
Ah, NVM, found it: PA1005.100NL
I thought they were called "current transducers". (Still "TR")
@@ZomB1986 At component level only current transformers exist.
I have 17 Enphase microinverters on my roof, installed 7 years ago. Over last 2 years, four of them have failed one by one, which is about 600 times their claimed failure rate of 50 per million per year. I suspect they would have lasted longer in Arizona or Australia, but in wet, humid and often overcast Southeast US, with all the thermal expansion and contraction, you just can't keep moisture out of those boxes no matter how hard you try. Theoretically they are under warranty but kind of a nightmare getting them replaced, because I'm too old to be getting up on the roof and the outfit that installed them is no longer in business. Enphase doesn't like dealing with homeowners anyway, so I have to find a certified Enphase installer willing to work on somebody else's system, not so easy. And the icing on the cake, so to speak - the warranty doesn't cover labor!
Wow, four of them?
Lots of hardware up on the roof, those primary DC caps are under a lot of stress, switch mod ripple current high temperatures (especially in AZ) and anything connected to the AC mains is subject to all sorts of nasty transients that are very hard to protect against. Would be very interesting to see the RCA (root cause analysis) of those micro inverters.
Yikes. We have 16 which have been up for two years. Fingers crossed.
@@EEVblog enphase does not like humid weather. They are not known for their reliabillty in europe. Many people dont use micro inverters because they fail often and are a B to replace compared to a regular inverter in the attic
It's tough to begin planning out a system like this. There are so many new names, and so many _no-names,_ that you can't just say "oh yeah, Eaton, they should know what they're doing..." I'm in the far north, with potentially a couple months of well-below-freezing temperatures, and lots and lots of precipitation. It would make me nervous to put _any_ active electronics outside. (Although baking in the sun can't be too easy on them either.)
I want to DIY, because: cheaper, more fun; but also because if you pick an installer, they're just going to use what they carry -- which is either what's best for their profit margin, or what they can get, or simply just what they've always used.
Learning curves always suck. What can you do.
Thanks! I liked the way you did the schematic over the parts. Makes it a lot easier to comprehend.
Regarding the AC plug - there are essentially two versions: daisy chain (double AC plug) or trunk like this one (you plug it into "T" connector on trunk AC cable)
Looks like its following a Microchip AN1338 app note but using a Ti processor. Basically the two large PQ cores are the inductors for two interleaved flyback boost converters. They are interleave for efficiency. These produce a high voltage DC that is galvanically isolated from the panel input DC by the inductor's secondary winding. The DC then runs to a combined PWM and un-folder stage to produce the AC output sign wave. The un-folder makes the opposite half phase. Micro inverters are current sources not voltage sources. You can't expect your 350W inverter to change the grid voltage but you can push current to the grid. I didn't go through the code but my impression is it adjusts the voltage phase relative to the grid phase to control the current supplied to the grid and to remain within the MPTT range of the panel. The DSP math is quite complex, with several servo loops, PLL's and error checking. All the while running the flyback converters, PWM and unfolder circuits. Lots of factors to consider. Every so often they turn off and check that the grid is still alive and shut down if the grid has failed. Don't want to fry the lineman up in the bucket truck.
Nice find. Yeah, almost indential topology.
Always wanted to know how they know grid is there or not WITHOUT turning its output off and listening. And you said its that simple, they just turn off for a few cycles🙂
Apart from detecting an overload, any other way to detect grid is down or not without dropping output power?
Thanks for pointing to interesting lecture 😊
Great video. Watching all the way from Western Kenya.
Dave the TMS320 is a mainstay of solar (and motor control). Especially the Piccolo family. Why? They have a High Resolution PWM (HRPWM) that uses some magic technique to get PWM resolution greater than the clock for very precise mico adjustments. I think it's 150pico second steps (less than 200ps anyway)! I expected to see a TMS320 and lo and behold we have it.
True. People tend to forget the TMS320 is a very loose branding that TI has applied to many families of DSPs over the last 30 plus years, with quite several completely disparate CPU and instruction set architectures (I can recall seven or eight different families at least without looking anything up). Some of the newer devices with dedicated power control peripherals certainly fit well here.
It would be interesting to know *which* TMS320 is used in there
Love your Video. Cried a bit though watching you tearing down a unit, which was very hard to get for month here due to supply chain issues. The educational aspect was worth it, though.
I had never heard of Hoymiles before the hardware appeared in your mailbag. Apparently we've all been missing out. Looks like they're ticking all the boxes for safety and reliability. Thanks for the teardown, despite the goop.
one of the only micros that passed ÖVE and DVE Testing and are certified to run here in germany/austria on the grid.
I had to replace the relays on a full size inverter that weighed about 30kg. Some scary caps in there, I definitely triple checked they were discharged 👍 Was a very nicely designed piece of kit, very high quality boards in it.
Good job!
Almost can( re) projecting my own device!
It was wherry deep!
That was a cool tear down. A video on how these work would actually be really cool. Ex: how do they sync with the grid, and how do they detect if it goes down. Especially when there are many of these on the grid, how does one inverter not think another inverter is "the grid" and keep going, for example. I presume it goes by current draw, if grid goes down it will try to pull massive current?
Or even just how to DC to AC conversion works.
I was about to say a similar comment. How does the microinvertor keep in phase with the grid when it is supplying power to it?
@@dogastus Well they measure the voltage at every microsecond so they can follow.
The inverter turns off when voltages or currents go off limits. A blackout looks like an eventual voltage spike (depending on where in the phase the current stopped) followed by a shortcircuit = current too high on the grid side.
@@AndreasDelleske one would think that current would flow in the inverse direction and the solar panel would become an LED.
just kidding
Very interesting teardown and going through the path like that. I would like to see another to see how they compare to be honest.
Great tear down very useful for beginners like me, Cheers Brother.
Thank you Dave, I really wanted to see a teardown of a microinverter.
Wow thank you for this, I always wondered how that would look like from the inside.
I enjoyed this teardown. Pretty popular devices right now.
@offgridgarage
Yes. Please review also the other inverter.
The electrolytic capacitors store energy to balance the 2x50Hz mains power pulsation, not clouds or birds covering the panel.
Yeah, I was going to say the same. Otherwise you drop efficiency a load - you have to draw a constant DC current from the panel at the MPPT to get max power output from the PV panel.
That goo looked nice, I’m ordering 10 of these. I would love a teardown of a different micro inverter!
Just don't put it down on the desk and let it pick up solder blobs and other detritus, and then let it flow back over high voltage high power electronics.
Nice to see. There's an HM400 in the very small system that I installed in my daughter's apartment. We have HM1500 on our second system on the garage roof. They seem well engineered.
Interesting black "goo". I have disassembled two IGBT modules at different times. In comparison to your semi rigid stuff, what I found inside was crystal clear stuff (except the black burnt traces indicating electrical tunneling). But, clear or already burnt, it still was sticky and stretchy beyond my belief. The modules were about 6" by 3" by 0.5". They contained a 6 diode 3-phase rectifier bridge and 4 IGBT H-bridge for variable frequency drive and a "bonus" IGBT for a brake. It took me over ten hours to pull most of the goo out with tweezers, forceps, small screw driver and exacto knife. Half of the time was spent on cleaning my tools with paper towels...
More please, I always dreamed of making these as DIY but it is beyond my skill level.
This video gave me a rough understanding
I, too, would love to see teardowns of different micro inverters to see the differences in design and operation, please!
Thanks,
KW
That's the same goo that I pulled out of an Enphase IQ7+ microinverter. Sticks well when thrown at a wall. 🤪
I'm not great with electronics but great explanations of it all!
I say keep on opening them up until we see something weird/different. Bound to be some gems out there.
Interesting! I was sold IQ7 Enphase from the solar salesman, but the installer wanted to install Hoymile inverters with 4 panels to each. They didn't look impressive from a general overview, and I didn't like their production dashboard. I insisted on getting the Enphase, but these Hoymiles don't look too bad. Definitely would be interested in seeing what the IQ7 inverters look like in comparison!
I add it to my schematic playlist!
When I saw it! Hi resolution is good, but 2xxx is greater!
Complete good job!
I wish all potting compound would be like this it would be so much fun.
Oooobaby can’t wait to watch this later
Yeah! Please do the ZBeny review! :)
My congratulations from Krymia
We are expecting for U!
Th-x for all!
It would be cool to see some testing on these before you tear them down. Hooking them up to the lab power supplies and measuring output waveform and the thermal output at the case would be examples. Maybe also do some over driving of the inputs and see what breaks first?
To a degree I wouldn't be surprised if the "transformer" Dave suspects to be the main isolation transformer to simply be an inductor.
And instead have the two DC-DC converters handle the isolation. And I suspect this to be the case given the two optocouplers top left at 21:30 going over to towards the "transformer". And there is more optocouplers on the back of the board for this region too.
The advantage of isolating in the DC-DC ones is that one can make a compact design able to handle high power.
And then use a class D output stage to generate the low frequency AC for the mains voltage. Ferrite transformers don't tend to like low frequency stuff, especially at high currents. Tends to over saturate and do a poor job. But this isn't a problem if one switches a class D amp at high frequencies to generate a low frequency signal. Efficiency is typically fairly decent too.
Yes, correct, it's a common mode inductor. See the pinned comment. My brain was not engaged.
Totally, a iron transformer for mains frequency would be way bigger.
@@EEVblog It is easy to make these sorts of mistakes when faced with an unknown circuit. Educated guesses and a bit of fast analysis is the way to go.
One can also jokingly say that a camera removes a good few IQ points to say the least. The spur of the moment reacting to something "live" isn't usually the best approach to also remain correct. But does give useful insight regardless and something for us commenters to ponder over as well.
Overall, a decent video.
Though, first thing I looked for where how the solar panel and main's were isolated, and where. Tracking down opto couplers, transformers and such clues to potential DC isolation. And generally following the copper-less valley across the board. Since large bulky inductors/transformers/chokes are usually a black box until one does a continuity check.
@@erlendse That were my main suspicion as to why the DC isolation must be elsewhere.
Also helps that I for fun designed my own grid tie "transformerless" inverter a few months ago out of pure curiosity to how one would do such. (Designing a circuit based on pure "This is the goal" is more fun than looking up how others have actually done it already. Usually one stumbles down a few rabbit holes along the way, learn some tricks, and generally find a few alternate solutions to a problem.)
It would be great if you ranked them: for example: temp management via thermal camera, protection for reverse polarity or overvoltage
yes please, i like knowing the failure points of these
☺
The cable glands and the seal on the lid that is to flexible with to little screws. I opened my DS3 AP-Systems; same goo and waterdrops in all 4 corners within 6 montths after install.
My solar installer wired one of my 9 panel strings reversed polarity into the hybrid inverter. Managed to handle it fine, i was impressed. Though it would have at least destroyed the mppt for that string, but no... It's running fine...
Thanks for sharing!!!!
One more inverter for comparison would be good.
The tiny transformers are CTs for the power switches
ChargerLab channel just did a teardown of the Enphase IQ7+ micro inverter today. It must be a trend! 😆 Their layout seems a bit different, but they also use a lot of input capacitors.
I would love to see the switching topology of this inverter since me and a friend started our thesis making a 2kw inverter
I would like to evaluate the micro inverters based on emc compliance and testing. In our country basically every imported micro inverter fails to meet regulation and its a big problem!
definitely more inverter teardowns
Just I recognize that is a HMS version. The models with HM and MI it exist already a opens source project in github (Ahoy and OpenDTU). With that you can read the inverter and control it.
The HMS use a other frequency (868mhz) and it is in reingeneering process already.
It is, in fact, a differential mode filter to filter out the switching harmonics.
Hi Dave
what great timing , I was looking at these for my new installation.
I have heard these units run bloody hot even when ambient is under 30 deg C , this worries me for longevity when compared to Enphase.
What have you heard and your thoughts.
I was also lucky enough to meet you at Norwest mall a year ago, keep up the good work.
Cheers
A few years ago I opened an Enphase microinverter and it was fully potted with the same kind of material. Yup, it liked to stick in components like inductors :) In my case, the potting material seemed to kind of flow back into place with a little bit of heat and time - warmed it over 30 minutes or so on low temp in my "projects oven" in the garage.
Looking back in my circuit pics, the Enphase inverters (at least the model I have) don't have fusing in the PV input side either. And they have the same double-transformers that you showed here, so I'll guess the same push-pull "interleaved" drive that you pondered of them. I apparently didn't take pictures of the bottom side where the FETs live.
Of course, their only copying enphase. They developed the "borrowed" idea In the 1st place, which is cool to me, I think IP Protection Laws are nothing but bull**** anyway. But anyway, I have a question for you. Do you have grid-connected solar? If so, Why isn't it necessary that your inverters must cease to generate electricity when the grid goes down, right when you could use it the most? And why are you not fighting this tyranny and theft you are subjected to?
@@mpirron1 Tyranny?
There are sound technical and safety reasons to not having a random (and out of utility control) assortment of power sources pushing against a broken grid. At the most basic level, isn't the "grid-tie" concept orphaned if there's no grid to tie to? The "tyranny" of physics is always ready to get involved too.
Also there are solutions to your no-power-when-there's-no-power problem. Of course they center around batteries, can involve transfer switches and cost more.
Ah, the tyranny of No Free Lunch.
@@Randrew but its okay for ice generators?? Why can't I install an automated transfer switch on my inverter?
No, that's untrue. There is no code provision in the country for DC coupled Transfer switching. Even though it works perfectly fine. And the backup battery solutions that code allows is also tyrannical, I still can't use my solar panels for power. Only for charging the batteries. Look, here's the bottom line. If the grid operator is not going to be able to Monitor and siphon off your solar generation, then its not going to be used to generate AC power, period and its pathological.
@@Randrew Tell me this, smart guy Why is it illegal for me to send my excess solar generation straight to ground if I am connected to the grid? Why am I forced to sell it to the grid operator? Why Is he paying me 1/6th of what I'm paying him? And only in the form of credits that cannot be accrued? Why can I not be paid in cash like I have to pay? Those provisions don't sound authoritarian in the least to you. I suppose.
The DC output of the solar panel is not as clean as you want it. They actually have a fairly high source resistance. I forgot how many cells you have to have in series to get 60 volts. Adds up to a lot of slop in the voltage hence a lot of beefy caps to smooth it out. What kind of current pulses do you have at 400 watts?
Thanks for this. If you apply the panel backwards, the diodes in the FETS limits the voltage to -0.7V. I routinely get 356W out of my HM-350NT and they blow away my IQ8+. They're excellent, IMO.
haha that’s not a good thing. a -0.7v “limit” is a short across the panels...
@@Ferraday They are current limited to Isc, it doesn't hurt anything for a short period, and doesn't damage the inverter.
@@Ferraday Across one panel - it doesn't matter since they'll only get as hot as they would with no load anyway. The panel will get the same amount of energy from the sun whether it's shorted, disconnected or properly connected. Only difference is where the heat gets dissipated. If the panel can survive sitting out in the sun, it can survive being shorted.
I'm more concerned about the 0.7v drop across the FETs. At around 13 amps short circuit, they'll have to dissipate 9.1 watts worth of heating. Better hope that thermally conductive potting compound is up to the job since that's the only thing moving the heat from the PCB to the outer case.
@@wasddasw6485 Clamped at around only 1v the panel will be so far from it's MPP that the output current will be nowhere near the rated value of that panel
Making the insaney more plainy. Thank you
Input fuses are not needed because the panels are current limited (Isc) so even if you reversed polarity they would not source any extra current to blow the fuses anyway.
True.
If installing one or two PV panels say just to supplement a few watts grid tied , dose Hoymiles Micro Inverters need the gateway to wake them up like Enphase micro inverters ?
The square device on top of the AC side MOV is most likely a thermal fuse in series with the MOV to guard against short circuit failure of the MOVs. Quite typical arangement for surge protection. Will isolate a MOV that has failed low impeadance. You loose the surge protection but it shouldn't catch fire. Safety feature rather than functional benefit.
The h-bridge drive after the flyback looks like it might be a full bridge driven LLC converter? - hence the two caps, one for DC, one for AC resonance. Did you check the pin connections there?
Great video. I do wonder if the drawing of the isolation transformer is right. It would have to output 240VAC at 50/60 Hz, rated for 400VA. It seems awfully small for this job.
No. The mains voltage and waveform will be approximated through PWM modulating the Power at high frequency.
I was thinking the same thing. I think what Dave thought is the 'isolation transformer' is actually the output filter, and the flybacks are the ones that perform the isolation. That little thing will never do 400VA at 50Hz.
@@andreasdill4329 That PWM signal would still contain a very larege 50Hz component. (check the spectrum of a high frequency PWM 'approximation' of a 50Hz sine wave). You can't pass that through a high-frequency transformer.
Yes, you are correct, I should have actually put my thinking cap on, it's a common mode choke.
I believe your are correct, I think that is a common mode choke on the AC line side. From what I have seen the PWM is done in the unfolder after the interleaved flyback converter stage. Very clever, get your PWM 1/2 wave sine conversion and polarity swapping for the second 1/2 wave with the same components.
It would be unusual to fit a spark gap over the top of an MOV, it is more likely to be a thermal sensing device to check if the MOV's are getting hot through over voltage.
Back when I worked on inverters the TI chips had much faster and more capable ADC which made the control software easier to write.
There was a fireman that died in Germany due to DC arc over a few years back. Since then they have to check the solar panels before starting the fire fighting.
Note, that even if its in nighttime. Just the back light from the fire, might charge up the panels to a considerate voltage, even if there is hardly any current.
This is a problem, because if your house is on fire... for some other reason, and they can´t verify that your pannels are AC or low voltage DC, they will not save your house. (well.. they might if its just a minor fire, but if its a big fire and they have to spray the whole house)
do some more of them!!!!
in derek's @veritasium video representing poynting vector diagram ,do we still use ampere's hand rule to find magnetic fields using conventional current? (not electron movement ?)
Please consider working another micro inverter for comparison. I'm using Enphase on my panels. Thanks for what YOU do. ...N3JLR
Hi Dave, I wonder how mains sense works. How it can differentiate mains coming from grid from mains coming from another micro inverter? Can it be fooled by lets say UPS?
Certianly. Some of them have a bit of an iffy rep. I was thinking of getting 3 of these for the 3 spare panels I have. However the cost!! So I bought a Solis 1 KW inverter 2nd hand. (As new under speced by an installer) so it has only a few hours of use. This will tie in with my 5 Kw Solis inverter. It wiĺl run 4x 260w panels so I can add another panel if I want. It cost less than one 300w micro inverter so all good.
That thermal 'putty' would be nice to identify and source.
By using the putty, no pressure equalization element (valve) is needed, since there is practically no air in the housing - right?
Does this work well in practice?
Might be also a good alternative (instead of controlled ventilation) for outdoor home projects (Wi-Fi APs...)?!
I think they are using two 180 degree interleaved step up converters and than make the AC which they then step up to 230ac using that other output transformer. That could be, instead of using two fkyback with all their disadvantages vs step up in CCM.
Theres an open source solution for the wireless protocol with an ESP32 and some wireless module as a bridge. Got it running, works like a charm and only costs cents!
Can you share the solution?
That potting compound looks like a goopy silpad!
Please do that other inverter teardown.
My son's friend is a lineman. Protocol states that each primary phase must be grounded before any work can be done on the conductors. However, it is interesting to note that no such protocol exists for the stepped down 240V residential connections to the distribution transformer. As more and more solar go online I think these rules need to be changed.
3:00 Dave playing with EE play-doh lol.
Those Caps are called DC-Link capacitors, mainly energy buffer und reduction of current ripple, a common thing in Inverters 👍
And regarding the TMS320, no suprise 🙂 the C2000 is still being used today, but mainly as a redundency/safety controller not as a main MCU
Thank You Everybody for All that you are doing for our Planet Earth.... Peace.. Shalom.. Salam.. Namaste .. 🙏🏻 😊 🌈 ✌ 🌷 ☮ ❤🕊
High frequency High voltage side via Trough relay!
I'd like to get a deep review of the HMT-1800/2250-6T though.
i wanna know whats that black cover or gel for. does that make the inverter hotter in the inside? in my thinking the less or air that have the cooler it will be?
The little RF communication board has its own FCC ID ...
I know someone had anti-islanding fail because two different inverters fed the grid keeping each other awake.
Aishi caps are used in CFLs a lot._
I considered this to achieve island on a boat, haven't tested yet.
If there are multiple of these micro-inverters connected together, how do the units keep all AC voltage wave forms in phase?
And what is the max units connected together?
If you have multiple strings, how do they stay in phase at the breaker panel?
thanks
Single phase AC has a sine^2 power profile where the PV panels need a constant DC load to provide maximum power. You don't want 2x AC line frequency power flow ripple current to show up on panels or you lose power from PV panel.
That is the reason for all the electrolytics across PV inputs and the weak component reliability link in the micro-inverter scheme. Electrolytic caps MTBF is highly dependent on their operating temp. Micro-inverters operate in a very hot environment behind PV panels, likely a few inches from a hot roof. Not great for electrolytic caps longevity.
Those axial power resistors are pretty high spec for carbon film jobbies - 2% tolerance, 25 ppm/K. Very not bad.
Why not metal film or metal oxide?
Metal oxide are flameproof and grunty.
I don't think, that the transformer on the top (AC-output) is an isolating one. It's too tiny for 400W @50Hz. I guess it's a filter in mH range.
Though I couldn't see the look on your face while you depotted this thing, I could practically *hear* the gigantic grin.
I'd be real interested to know this thermal compound. You got any info from them?
you can talk to them via an NRF and openDTU :)
Prices have gone through the roof since they are controlable by opensource software
Hi @Peter Kowalsky,
MI- and HM-Models did use NRF24L01+ for communication via 2.4GHz Enhanced Shock Burst at 250kBps.
But recent HMS- and HMT-Models instead employ an CMT2300A for communication via 868MHz / 915MHz at an expected 125kBps rate.
OpenDTU and AhoyDTU do not support HMS-/HMT-Model communication yet. But we are working on that :D
You may check our Wiki for the Protocol and some of the details for Germany and Austria,
in case you want to keep the produced signal in line with the local Grid Profile(s).
@@karlakunze9823 thanks for the info karla!
I'm missing something: at what frequency does the transformer in the top position works? Souldn't it be the mains frequency? If so, with that size?
@ElectricExperimentsRobert33 has done a really good video showing the difference between switching AC versus DC. Well worth a look.
So gas discharge between the mains, and another between mains and ground. Good protection in case the mains are subject to something harsh, like a lightning strike?
nope. this will protect only from minor arcing, like f.e. ballast from fluorescent tube kicking in or disconnecting wall-wart . Lightning strike has current of about 10 000A. For 0.1ohm protection, this means 1000V spike . Also lightning strike generates huge EMP.
IMHO best protection against lightning is insurance, as anything else just adds incredible complexity and cost.
Another good protection are dpdt relays with at least 5KV isolation on both input and output.
As storms usually do not happen in clear sky, if there is no sun unit should be disconnected and grounded by relays. Usually spikes coming from storm can be also detected on AC side. Most UPS devices have some kind of protection algorithm implemented basing on detecting voltage spikes in the grid, throwing protective relay and switching to battery mode.
That is a pretty cool (pun intended) solution for something that is not needed to be opened..
I wonder if anyway to use such microinvertors off-grid?
Yeah I know they are designed to be grid invertors and must switch off when main power disappears. But maybe some solution exists for off-grid.
For example will such invertors work if use pure sine invertor from the battery as the "master sine"?
Assuming no ingress, what do you think would fail first? (My bet is a 65V max input rating could age those 63V input caps. I like to see 100% margins on input/output caps.)
Residential panels are signifantly under that though.
@@EEVblog I could see someone putting a couple in series on each inverter, especially if they are hedging against a poor roof angle or something.
Very disappointed to see a customer facing rating HIGHER than that on the caps. Negative headroom, and on something typically installed out in the heat.
@@tactileslut it's all a continuum curve anyway. It's just less time before it begins to fail.
@@tactileslut You have to consider that in normal operation, the panel operates at about 70% of rated open circuit voltage due to the MPPT. So, it would only ever experience 65 V in case of maximum solar irradiation during a grid failure. I would still not rate such an inverter for 65 V though.
hello great video.. I have to repair the enphase microinverter which does not work because of 1 swollen capacitor.. I removed the gray paste.. but it must be replaced for the seal. Did you find the name of this thermal paste.. thank you
I would like to see the other teardown
more and more ppl is ordered to shut down there solar systems here if they use inverters of that type (one for every panel) they make so much radio noise together that they shut down airport radar and other communication systems. yes they complies by itself.. many of them together do not.
How do they synchronize the current phase with grid? 🤔
It would have been nice to see the THD distortion, there has to be quite substantial crossover distortion 1 - 5 % ?
Can you do a video where you go into detail about circuit protection like with MOFs etc? I know little about what you can do and should do. There was sadly nothing lectured in university despite this maybe being the most important thing when designing an electric device…
Also would be great if someone could recommend some existing tutorials.