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"Do Not Disconnect Under Load"?

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Posted by Ron Hardin on June 29, 2012, 12:12 am
 
My new Instaparkļ 50W Mono-crystalline Solar
Panel says "Do not disconnect under load."

Why?

Are they concerned about sparks in the connectors?

High voltage transients wiping out a
semiconductor?

Do they mean disconnect at the panel or even at
the solar controller?

If so how do you disconnect them without waiting
for night?
--
rhhardin@mindspring.com

On the internet, nobody knows you're a jerk.

Posted by Ecnerwal on June 29, 2012, 2:07 am
 


If you wanna know what they mean, why not ask them, rather than us?


Use a blanket. Not exactly rocket science.

--
Cats, coffee, chocolate...vices to live by
Please don't feed the trolls. Killfile and ignore them so they will go away.

Posted by brewman1947 on March 20, 2016, 1:11 am
 On Thursday, June 28, 2012 at 7:07:40 PM UTC-7, Ecnerwal wrote:

yer a bit ruff there mate, have a brewsky

Posted by argusy on April 2, 2016, 4:25 am
 On 20/03/2016 11:41 AM, brewman1947@gmail.com wrote:

Wait till it's a sunny day, and face your panel to the sun.

Now, hold the end connections about two feet from anything flammable (well,  
everything, really) and very carefully touch them together, (that will produce a  
momentary 'splat') then pull the connectors apart, slowly. You could get arcing.
See how far you get before the arcing stops.

For a 50W panel, it may be a short display, (and possibly fry the panel) but  
consider this -
Put ten of these 50W solar panels in series, and the arcing could be a couple of  
centimeters. Great fire starter

if you ever do the same to just one connector on a 1.5Kw array (eight 50V  
panels) mounted on the roof of a house during a sunny midday, then -

I'd suggest wearing insulated gloves, and wear welder's glasses to protect your  
eyes. (UV is also produced).

It may be a good idea to have an electrician with a powder fire extinguisher  
standing by. (You may get a surprise and drop the cables, and they're still arcing)

400 Volts (eight 50V, 200 watt panels) capable of providing about 4 amps while  
arcing is really something to see, AND IT'S CONTINUOUS (the sun is shining,  
right). While the arc is maintained, the air around the arc is ionised, which  
allows the arc to extend. I've seen a Solar array produce an arc about 80mm.

IF you keep the arc going for a minute or two, then pull far enough apart to  
stop the arcing, the cables will be bloody hot, mate, and the plastic connector  
coverings will turn into a molten mass.

THEN you will understand "DO NOT DISCONNECT UNDER LOAD".

And that's why the signage is put on even 50W panels.

As has been pointed out, covering your 50W panel during daylight with a large  
towel (blanket, coat, pillow, your shadow) will kill the power. Logical...

Posted by argusy on July 1, 2012, 4:27 am
 On 29/06/12 9:42 AM, Ron Hardin wrote:

Seeing your panel is only 12V, probably not a problem, unless you've just set it
up at right angles to the sun, and the sun is near its zenith.
Then your panel, being cool of course, is producing it's maximum current (hah!)
of just over 4 amps, if you short out the terminals

Now that that explanation is out of the way, disconnecting the panel under those
conditions shouldn't affect whatever-you-had-connected, as you've now
disconnected it. What MAY happen is that at the moment of disconnection, as you
pull the cables apart, somewhere between a fifth of fuck-all and a poofteenth of
a millimeter, there MAY be a spark for a microsecond that's drawing all of four
amps.
This may be enough to induce an electric current in anything sensitive to an
electromagnetic field if it's close enough.

So don't disconnect your cables by laying them over your LCD watch, and pulling
them apart. You just may destroy your watch!!

That's the most pessimistic outlook.

If you're an optimist, then don't bother with that warning - you should live a
long time, and you probably won't destroy anything.

But don't blame the manufacturer if, by some strange chance, you stop your i-Pad
from working when it was just a couple of inches away. That's why the warning -
it's highly improbable that a spark from your panel would destroy anything
electronic, but the possibility's there, and the manufacturer has to cover his
butt from stupidity making an expensive legal claim, blaming that spark to cause
a chain of events that put you in hospital or destroyed
<house/caravan/shed/whatever>

I see someone else has made the right observation about what to do during the
day. It's the same as a fire - remove the heat and the fire goes out!!


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