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How about a solar car port on a budget?


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7 hours ago, carlyai said:

Sorry if this is unhelpful, but there's a YouTube video by Sam Ben-Yaakov on building a MOSFET snubber. Bit more involved than a single capacitor.

Two different options— a snubber or a surge suppression capacitor with the MOV. The snubber is generally better, but the capacitor could do the job potentially.  
 

I would be curious if the enphase inverters have similar issues. At 4-5,000B for a single panel Microinverter the economics might not work though. 

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Some of you may remember us building this back in 2015.     Thread here https://forum.thaivisa.com/topic/481794-housebuilding-thread/?do=findComment&comment=9603407  

Warning - solar panels are 'kin heavy when you have to lift them onto the roof 🙂   Finally, the 4 panels are in place.     Panels are fixed using plates and long screws i

Something like this:-  

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11 hours ago, Muhendis said:

That is undoubtedly a design shortfall.

 

No doubt whatsoever.

 

I still suspect the actual damage is occuring when the power goes off rather than when it returns (which is when the fuse pops).

 

The issue has certainly been around for a while if you look back at the various info on t'internet. I was rather hoping they'd sussed it with the updated design. There is no doubt that they are aware of the weakness, the support engineer immediately knew what was wrong and the spares needed to fix it when I described what had happened.

 

I agree there's not a lot we, as users, can do apart from keep fixing the fried FETs and hope that daytime power failures continue to be rare😞

 

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1 hour ago, Crossy said:

the actual damage is occuring when the power goes off rather than when it returns

The way to confirm this would be to disconnect city power next time you are on full load, then check the outputs of the individual micro inverters. Switching things back on again after this might be ok if the load is removed first.

Perhaps the supplier should include an inexhaustible supply of bits, a soldering iron and some explicit instructions. It seems that this micro inverter is not suitable for an unskilled novice.  

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1 hour ago, Crossy said:

 

No doubt whatsoever.

 

I still suspect the actual damage is occuring when the power goes off rather than when it returns (which is when the fuse pops).

 

I agree there's not a lot we, as users, can do apart from keep fixing the fried FETs and hope that daytime power failures continue to be rare😞

 

I have no understanding of the way the Electronic systems work but logically wouldn’t it be possible to add in a normally off contactor into the mains connection so that the restore of the mains link is no longer automatic or can not happen while the panels are producing full power to the inverter when the mains link is re-established 

 

If the failure is not instantaneous with the power cut then a mains powered N.O. Contactor between the panels and the inverter might be able to cut the supply to the inverter before the majic smoke can escape.

 

please shoot down these ideas if they won’t work or you’ve already discarded them. 

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12 hours ago, tjo o tjim said:

I would be curious if the enphase inverters have similar issues. At 4-5,000B for a single panel Microinverter the economics might not work though. 

 

My investigations have concentrated on the WVC inverters although other micro inverters have popped up in the results with similar faults (fried MOSFETs).

 

I've also looked for more robust devices (the existing ones are 650V) but anything higher (1000V) at similar current rating (30A) are either not available in the TO-220 package and/or are considerably more expensive. 

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3 minutes ago, sometimewoodworker said:

If the failure is not instantaneous with the power cut

 

From other reports it seems that the failure IS instantaneous (very fast) when the power cuts. The shorted devices then sit there until the power returns at which point the fuse pops.

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7 minutes ago, Crossy said:

 

From other reports it seems that the failure IS instantaneous (very fast) when the power cuts. The shorted devices then sit there until the power returns at which point the fuse pops.

So not ideal and maybe not cost effective but the fuse popping part could probably be stopped with my idea?

Edited by sometimewoodworker
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10 minutes ago, sometimewoodworker said:

I have no understanding of the way the Electronic systems work but logically wouldn’t it be possible to add in a normally off contactor into the mains connection so that the restore of the mains link is no longer automatic or can not happen while the panels are producing full power to the inverter when the mains link is re-established 

A contractor operates in about 20ms, a fuse in about 5ms, and a MOV in about 3ms. The igbt switches in about 50us, which is the time required to protect. 
 

The problem is instantaneously you can get “infinite” reverse bias voltage across the SCR/IGBT, and the only real solution is to dissipate that energy. That happens when power returns generally. 

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By the way, the manufacturer will fix any failed inverters for free. You pay shipping both ways which equates to about half the cost of a replacement unit. I only got spares (again free + shipping) because the support staff understood that I'm in the position to actually fix the unit.

 

I've located a supplier of the devices on AliExpress for about 2 bucks a piece (with free shipping) which actually works out about the same as getting them from the manufacturer (6 FETs plus 2 fuses free + $15 express shipping) but they take 30 days to arrive.

 

I don't have the drawings but it seems these inverters may have one output stage per panel, it was only one pair of MOSFETs that actually failed (I'm replacing all 4 anyway, I'll keep the "good" ones for emergencies). There's a possibility that simply removing the failed devices and replacing the fuse would return the unit to operation at 50% output. I may try this next time, I have no doubt there will be a next time I'm afraid (I've ordered 20 spares which probably guarantees that I won't see another failure).

 

 

Slightly off-topic, but a lot of commercial electronics has a set of "stock" failures that appear after a design has been in service for a while. i.e. When you see one on your bench you can pretty much guarantee what the fix is. CPC (now long defunct) used to do repair kits for the popular chassis containing all the bits needed to fix the main faults. Most of the time the service chaps didn't even bother to diagnose the issue, just install the repair kit and test.

 

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If you had enough of them you could send them back four at at time making shipping more cost effective.

Particularly since you have plans to expand. At some point they’d get them right.

Of course that would take the fun out of it...


Sent from my iPhone using Thaivisa Connect

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By the way, the manufacturer will fix any failed inverters for free. You pay shipping both ways which equates to about half the cost of a replacement unit. I only got spares (again free + shipping) because the support staff understood that I'm in the position to actually fix the unit.
 
I've located a supplier of the devices on AliExpress for about 2 bucks a piece (with free shipping) which actually works out about the same as getting them from the manufacturer (6 FETs plus 2 fuses free + $15 express shipping) but they take 30 days to arrive.
 
I don't have the drawings but it seems these inverters may have one output stage per panel, it was only one pair of MOSFETs that actually failed (I'm replacing all 4 anyway, I'll keep the "good" ones for emergencies). There's a possibility that simply removing the failed devices and replacing the fuse would return the unit to operation at 50% output. I may try this next time, I have no doubt there will be a next time I'm afraid (I've ordered 20 spares which probably guarantees that I won't see another failure).
 
 
Slightly off-topic, but a lot of commercial electronics has a set of "stock" failures that appear after a design has been in service for a while. i.e. When you see one on your bench you can pretty much guarantee what the fix is. CPC (now long defunct) used to do repair kits for the popular chassis containing all the bits needed to fix the main faults. Most of the time the service chaps didn't even bother to diagnose the issue, just install the repair kit and test.
 
Like a microwave system I consulted on, had a breadboard arrangement outside the main unit which containing connectors and all the transistors that blow up with lightning strikes. Just pop in a new set if T'sistors.

Sent from my SM-J700F using Tapatalk

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The most annoying part of this whole game is that the last 3 days since the inverter failed have been the best for generation on the remaining unit 😞

 

Meanwhile the 1,200W unit should arrive Tuesday so next weekend will be extra panel installing time.

 

I'm also going to re-configure the DC wiring to minimise the cable lengths, got to get every last Watt 🙂

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17 minutes ago, Crossy said:

The most annoying part of this whole game is that the last 3 days since the inverter failed have been the best for generation on the remaining unit 😞

Meanwhile the 1,200W unit should arrive Tuesday so next weekend will be extra panel installing time.

I'm also going to re-configure the DC wiring to minimise the cable lengths, got to get every last Watt 🙂

My Suoer D600D GTI is still working and only costs 2,650bht from Lazada.

27.3 units from my one panel so far this month, lost 1 day to rain, and another 1/2 day to clouds.

The panel was getting a bit dusty so I gave it a wipe today, one day I'll get around to adding a second panel.

 

Just got my bill, 271 units 1,075bht.

Edited by BritManToo
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