EEVblog #844 - Solar Panel Replacement

[EEVblog]

Dave replaces the shattered LG Mono-X solar panel on his home rooftop solar power system.
http://pvoutput.org/list.jsp?userid=22501
http://www.lg.com/au/commercial/mono-x-solar

[Brumby]

I was wondering how this was going...

[Brumby]

So, all done.  Has the next day 'Sun test' proven successful?

[Alexei.Polkhanov]

Hmm, I think "the projectile" may still be inside the panel. David maybe able to find it and if not I would have poured an opaque silicone at the place of impact and once it is solidifies I would try to lift it off carefully to get an imprint of whatever object hit it.

[EEVblog]

So, all done.  Has the next day 'Sun test' proven successful?

It works.

[richms]

That dent out the back is pretty epic!

Mine are going in on the 5th here. "2.6kw" system on the garage roof, hope I don't have anything like that happen since its a 45degree roof so not something that you can just walk on.

[Brumby]

That dent out the back is pretty epic!

Yeah - I thought so too.

For those who wish to study it....

[Alexei.Polkhanov]

Perhaps the object that hit the panel still in there beneath that plastic wrap?

[SL4P]

My guess would be a 12mm or 1/2-inch nut or similar.
Falling from 15000 feet - would make a serious dent - dissipated by the glass and panels.
Maybe not so lucky if it hit you on the head.

And if it hit the glass at an angle - it would bounce a fair distance away at 'terminal velocity'... tens of metres?

[Stonent]

Rinoa Super Genius did a video on trying to reseal some panels he got at the scrap heap.

[HackedFridgeMagnet]

I'm sure the shutdown procedure would be AC off first then DC. Its just to minimise arcing and thus help with the longevity of DC isolator.
The shutdown procedure is written on the white plaque on or near the inverter.
Startup is the opposite but I don't think it really matters.

Underneath one of the mid clamps should have been an Earth plate, when the new panel goes on, this one need to stay sitting in the correct position. This just pierces the oxide layer of the panel to attach the chassis to earth.
Just done my solar installer course, I know this stuff.
 

[EEVblog]

I'm sure the shutdown procedure would be AC off first then DC. Its just to minimise arcing and thus help with the longevity of DC isolator.

Not when you switch it off with bugger all power generated. I wasn't shutting the system down.
I only needed to isolate the DC side to work on it.

[HackedFridgeMagnet]

Ok I agree that waiting for the sun to go down is an effective way to prevent arcing when isolating the DC.

Unnecessary as it probably is I would normally shutdown the whole system.

ps. It is ok to short a solar panel or even the whole string.
Just one a range of tests done by the installer to check the integrity of the system.

[mtdoc]

A blanket or tarp thrown over the panels is a tried and true method as well.

Besides, proper rated DC shutoffs can be shut off while live without issue.

[coppice]

The air must be clean where Dave lives. Most cities have enough goo in the air that in 2.5 years it would have formed a sticky film over the back of the old panel, and a thick layer of dust would have stuck to the goo.

[coppice]

A blanket or tarp thrown over the panels is a tried and true method as well.

Besides, proper rated DC shutoffs can be shut off while live without issue.

Covering works, but covering a big area on your own can be pain, unless there is zero breeze. Although Dave waited until the generation had fallen, it had not ceased. He waited long enough for the current to fall, but there would have still been a fairly high voltage present. He might as well have turned off the isolator and done the work during the day, when there was more light to see by. The panels were installed in full sunlight. They can be serviced that way too.

[G7PSK]

The shape of the dent on the back of the panel suggests a bolt rather than a nut or a cricket ball, could even have been a spent bullet  they often impact sideways as the tumble and will travel for miles if shot into the air.

[EEVblog]

ps. It is ok to short a solar panel or even the whole string.

Once it's installed, yes.
I wouldn't do it with those connectors, you could pit the contacts. That's the whole point of the connector warnings.

[EEVblog]

could even have been a spent bullet  they often impact sideways as the tumble and will travel for miles if shot into the air.

This ain't the USA

[EEVblog]

Covering works, but covering a big area on your own can be pain, unless there is zero breeze. Although Dave waited until the generation had fallen, it had not ceased. He waited long enough for the current to fall, but there would have still been a fairly high voltage present. He might as well have turned off the isolator and done the work during the day, when there was more light to see by. The panels were installed in full sunlight. They can be serviced that way too.

The eye has a massive dynamic range, plenty to see by.

[coppice]

ps. It is ok to short a solar panel or even the whole string.

Once it's installed, yes.
I wouldn't do it with those connectors, you could pit the contacts. That's the whole point of the connector warnings.

Covering a big array with a blackout sheet may be a pain, but covering one panel to kill the flow of current while you replug things isn't.

[EEVblog]

The air must be clean where Dave lives.

Welcome to Australia

[coppice]

Covering works, but covering a big area on your own can be pain, unless there is zero breeze. Although Dave waited until the generation had fallen, it had not ceased. He waited long enough for the current to fall, but there would have still been a fairly high voltage present. He might as well have turned off the isolator and done the work during the day, when there was more light to see by. The panels were installed in full sunlight. They can be serviced that way too.

The eye has a massive dynamic range, plenty to see by.

Sure, but you said you hit a snag with a stuck bolt. If that had been more serious and taken you into darkness you would have ended up finishing the job in the next day's sunlight anyway. Its summer in Australia, so I guess it was pretty hot during the day. Working at dusk when the temperature is more comfortable makes a lot of sense, but these things have to be serviceable at any time of day.

[chickenHeadKnob]

You  said you had a bugger of a time getting those hold down bolts off. They look like they may be stainless steel. I discovered to my frustration, decades before the internets could help with preventive advice, that stainless hardware which isn't coated in anti-seize can gall and self weld dam near instantly.

[putz182]

Call me crazy, but don't believe it was an impact.

The glass cracking effect can be a shadowing effect result.
Watch the 2:20 minute video. There is a first shadowing in the last panel

You should check for hotspot when that happen.


You should also forward power the panel in the lab and check for defective cell as well.