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Shortcuiting the Solar PV Array

07/19/2017 11:54 PM

i have doubt on solar panel. if we are short circuit the positive and negative terminal Solar PV array(315 W Module-21 modules series), were it will damage the panel? i can able to measure the current flow!!! in peak hours its showing 8 A. when i opened the terminal i saw the fire arc. may i know its happening? can any one please explain?

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#1

Re: Shortcuiting the Solar PV array

07/20/2017 12:07 AM

If you have an active circuit and you break the connection you can sometimes see an arc between the separating contact points....You're producing around 6600 watts if all panels are operational....You can check the amount of current being produced by multiplying the amps times the volts, and determine if everything is working correctly....

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#2
In reply to #1

Re: Shortcuiting the Solar PV array

07/20/2017 12:14 AM

Hi guru,

when we are shortcircuiting the PV array, voltage will get zero right, so there is no power will not generate right?

so how arc will produce when i open the shorcircuited the PV array?

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#3
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Re: Shortcuiting the Solar PV array

07/20/2017 12:23 AM

Why would anybody shortcircuit the panels? That would be the fastest way to damage the equipment....If you tied the lead wires together you may have damaged the panels...The circuit is tested by multimeter for voltage with one lead to one side and the other to the other side...the amperage is tested under full load ie; charging battery bank or feeding the grid or other electrical load...

Read and follow instructions below....

http://www.selectsolar.co.uk/uploads/asset_file/How%20to%20Test.pdf

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#29
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Re: Shortcuiting the Solar PV array

07/25/2017 10:48 PM

You would short circuit a solar PV module.... with an ammeter, if you need to find the short-circuit current (ISC) for a particular solar irradiance (insolation) level. It's not the same as short circuiting a battery or a capacitor as it doesn't store energy, and you won't damage it or yourself (as long as you have your PPE on). On the reverse side of most panels you will usually find ISC values for 1 sun insolation (1000 W/m2) and sometimes for 800 W/m2 insolation. Current drawn from the PV module is proportional to the level of solar irradiance it's exposed to.

On any VI diagram for solar PV modules, the curve intersects the vertical axis at ISC and the horizontal at VOC (the open circuit voltage).

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#30
In reply to #29

Re: Shortcuiting the Solar PV array

07/26/2017 2:24 AM

The OP isn't describing short circuiting a solar PV module. The OP has described short circuiting 21 modules in series of 315W each.

Note, modules are not short circuit rated by what is produced with 21 in series....just one module shorted. Yes, it does make a difference. There is some resistance and the increase in voltage from 21 modules instead of just one means much higher current.

Here is an example of damage from this type of problem.

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#31
In reply to #30

Re: Shortcuiting the Solar PV array

07/26/2017 9:22 AM

What is really happening:
The one shaded cell exists as a single higher output impedance in series with the others, all of lower impedance while illuminated full sun.

Thus all the power dissipation is in the one shaded cell, and it gets really hot.

It is just moronic to attempt testing a solar bank this way. Stupid, stupid, stupid.

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#32
In reply to #30

Re: Shortcuiting the Solar PV array

07/26/2017 10:35 AM

I love the pic of that panel! It looks like a 1970's NASA instructional filmstrip.
How long has it been since anyone cut commercial wafers out of a 2" round die?

So while this example is clearly exaggerated for effect, it is possible, just unlikely in a modern commercial panel.

Besides, the shading failure can occur when a panel is *PROPERLY* loaded, or so it would seem.

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#33
In reply to #32

Re: Shortcuiting the Solar PV array

07/26/2017 10:48 AM

Could this bring back the saying: "Location, location, location!"

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#34
In reply to #32

Re: Shortcuiting the Solar PV array

07/26/2017 4:42 PM

There is a huge difference in heqt developed in a shaded cell under short circuit conditions and when a significant external resistance is present.

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#35
In reply to #34

Re: Shortcuiting the Solar PV array

07/26/2017 7:40 PM

Not according to the graph VT was kind enough to provide; 10% maybe?

And again the OP's question never mentioned a shaded cell.

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#37
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Re: Shortcuiting the Solar PV array

07/27/2017 9:18 PM

No, the difference can orders of magnitude different than 10% and cannot be seen in the graph you mention. It can be seen with basic knowledge of how a circuit works.

Compare two circuits:

In the first ciruit, 110V DC is applied across a single resistor of 1 Ω

In the second circuit 110V DC is applied across a 1 Ω resistor and a 10 Ω resistor connected in series.

The difference in the heat dissipated in the 1 Ω resistor in the two scenarios is obviously nonnegligible. The question is, would you consider describing the difference as 10% a reasonable approximation?

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#40
In reply to #37

Re: Shortcuiting the Solar PV array

07/28/2017 3:35 PM

PV junctions behave as *CURRENT* sources, not voltage.

Work the same problem when 8A flows through a 0.0625 ohm resistor in series with a 0.5V voltage source (actually a band-gap) then replace the battery with a short circuit and a forward diode and a few tens of milliohms.

The dissipation will spike, I agree, but not to the magnitude you've implied

It's been a really long time since I took a basic circuitry class.

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#36
In reply to #30

Re: Shortcuiting the Solar PV array

07/26/2017 10:57 PM

"21 modules instead of just one means much higher current"

I'm not sure if I would agree.... OP's series array is voltage additive. So, if (for a simple example) OP had twenty-one 24V/15A rated PV modules in series, he would end up with a 504V/15A system - the current has only one path, from the positive terminal, through the load to the negative terminal (I'm now wondering what OP's system is!). A 'parallel-connect' is curent additive and would produce that 'much higher' current you mention - a 24V/315A system. But you would be right about the lethal portential.... both systems - as they love to say in History channel's 'Forged in Fire', will kill!

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#38
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Re: Shortcuiting the Solar PV array

07/27/2017 9:43 PM

Voltage is additive. So it is effectively 21 times higher viewed over-simply. In reality in a real system, it is somewhat less than that.

In a real system, the short circuit is not without resistance. Either at a connection or the weakest cell....and a collection of 21 panels is very likely to contain a cell meaningfully weaker than most of the likely 1500+ other cells.

Lets say the weakest connection or weakest cell can be modeled well as a 2Ω resistance.

How much more current will be passing through a 2Ω resistor when over 400V is applied as opposed to around 20V is applied?

In my book, it qualifies as 'much higher'.

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#39
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Re: Shortcuiting the Solar PV array

07/28/2017 9:14 AM

By Jove! You get the brass ring! Spot on analysis once again.

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#41
In reply to #38

Re: Shortcuiting the Solar PV array

07/28/2017 5:12 PM

I would call a panel with a 2 ohm cell a manufacturer's defect!

Don't get me wrong, I agree that shorting a string is a *BAD IDEA*, but a quality set of panels should be able to withstand the mistake.

What you're still missing is that when the string is *SHORTED* the voltage collapses.

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#42
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Re: Shortcuiting the Solar PV array

07/31/2017 11:32 AM

Right. The large current shorted over the "intrinsic" Thevenin resistance of the string is what is then dissipating power. P=I2R, so all that does matter.

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#43
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Re: Shortcuiting the Solar PV array

07/31/2017 8:10 PM

Think about what it means when you say the voltage collapses. There is a low resistance conductor connecting the positive and negative terminals. How could voltage do anything other than appear to 'collapse'?

In fact voltage does not collapse. If it did, there would be no current. In fact the voltage is being used entirely on the effective internal resistance. Your multimeter is showing you zero voltage just like it does any other time you connect the leads to one another.

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#5
In reply to #2

Re: Shortcuiting the Solar PV array

07/20/2017 4:09 AM

So, wouldn't it be better to leave the array in open circuit rather than <...shortcircuiting...> it?

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#13
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Re: Shortcuiting the Solar PV array

07/20/2017 1:53 PM

Consider that your circuit has a very low capacitance, and a non-zero line inductance, thus there is a stored magnetic field in your circuit, and you may consider this is if the current has inertia (there is never truly zero potential, since the circuit itself is not a superconductor with zero Ohms resistance to DC), thus when you open that circuit, current wants to keep flowing, potential rises until a spark/arc is established.

WARNING!!! You may become killed or injured due to arc flash/arc blast, depending on the potential (nominal) of the circuit, and the ampacity of the conductors.

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#15
In reply to #13

Re: Shortcuiting the Solar PV array

07/20/2017 4:27 PM

Now I wonder who the smartaz was that marked me 5x off-topic?

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#17
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Re: Shortcuiting the Solar PV array

07/20/2017 4:53 PM

You did....You are automatically categorized as 'off topic' when you respond to an 'off topic' post.....you just have to uncheck the 'off topic' box when posting....

Yes, this comment is very likely to be considered 'off-topic'.

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#21
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Re: Shortcuiting the Solar PV array

07/21/2017 8:39 AM

Well then, we all know who the smartaz was! Thanks for the eminder (like a reminder, but no r).

BTW have a nice weekend on the beach, sipping your Mojitos, and gazing at the string bikini clad denizons of Miami?

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#4

Re: Shortcuiting the Solar PV array

07/20/2017 3:10 AM

1. Short circuit means constant current, not infinite current. And it is approximately nominal current.

http://www.samlexsolar.com/learning-center/solar-panels-characteristics.aspx

2. Stray inductance causes spark gaps.

https://www.allaboutcircuits.com/textbook/direct-current/chpt-15/inductors-and-calculus/

If anything is broken, it would be due to high voltage. There are no indicators of high current.

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#6
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Re: Shortcuiting the Solar PV array

07/20/2017 5:45 AM

Hi,

i want to know if we are connect the terminals of array, it will damage the panel or not. in web i read, if you are connecting(short circuiting) panel will not get damage. in that artical they said, voltage will get zero when we are closing the same circuit PV panel. so it will not damage. like that it was written.

But when i did that, there is no damage but when open the circuit, i saw little arc. so i want to know how it happened.

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#7
In reply to #6

Re: Shortcuiting the Solar PV array

07/20/2017 5:49 AM

Rather than repeating the ambition stated in the original posting on this topic, it would be far better to state WHY this ambition is to be realised, given that there is concern as to damaging the equipment in so doing!

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#8
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Re: Shortcuiting the Solar PV array

07/20/2017 5:57 AM

hi,

i want to know, details mentioned in the article true or not.

https://www.quora.com/What-happen-if-two-terminals-of-solar-panel-is-directly-short-circuited-Is-solar-panel-will-get-damage

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#9
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Re: Shortcuiting the Solar PV array

07/20/2017 6:24 AM

The forum wants to know:

  • WHY is there any intent to short the two terminals together?
  • WHY is there any perceived need to do so?
  • WHY is there any perceived desire to do so?
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#23
In reply to #8

Re: Shortcuiting the Solar PV array

07/21/2017 5:43 PM

I went to that link - there were 2 conflicting answers. You should listen to this one:

Mitesh Phalak, 10 years in Solar Energy, 2 patents, 2 commercialized products and lot more.. Answered Feb 8

Yes, It will get damaged if you short circuit the solar panels in sunlight, even if it is diffused.

In dark, the panel is in open circuit so there will not be any damage!

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#12
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Re: Shortcuiting the Solar PV array

07/20/2017 12:26 PM
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#10

Re: Shortcuiting the Solar PV Array

07/20/2017 6:39 AM

It is a mystery to this reader why anyone disconnecting a circuit carrying upwards of 8 amperes would not expect a spark therefrom at the moment of disconnection, and therefore a potential learning opportunity.

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#11

Re: Shortcuiting the Solar PV Array

07/20/2017 8:59 AM

Because of inductance in the circuit, voltage is generated when the current is interrupted, causing an arc.

It is unlikely to do damage to a solar array by shorting unless it is already faulty. No more power will be generated in the array than is being delivered by the sun shining on it.

https://electronics.stackexchange.com/questions/18092/solar-panel-short-circuit

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#14

Re: Shortcuiting the Solar PV Array

07/20/2017 3:59 PM

Don't short circuit solar panels as a general rule as this can damage them. They are probably ok however if they are still generating current.

Certainly don't try opening the 21 series-connected solar panel array circuit while it is generation power as a lethal voltage potential will likely exist even on an overcast day and it could kill you. The arc you saw was caused by breaking the circuit which had a considerable (and likely lethal) voltage behind it. DC voltage can kill just as easily as AC voltage.

Are you trained or qualified to work on these panels?

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#16
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Re: Shortcuiting the Solar PV Array

07/20/2017 4:28 PM

Silly Jack! The potential is not there until the short circuit is removed, then it builds due to stray inductance present.

The rest of your comment, of course, i agree with totally.

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#19
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Re: Shortcuiting the Solar PV Array

07/20/2017 6:02 PM

Oh, I thought the implication the potential will exist on opening the circuit was clear? A potential potential as it were.

I was trying to keep it as simple as possible given the posters previous comments.

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#18

Re: Shortcuiting the Solar PV Array

07/20/2017 6:01 PM

No. Whether the panel is short circuited or open circuited, the effect is the same. 100% of the captured energy is absorbed by the silicon and converted into heat. The panels actually operate *COOLER* when loaded, because the energy is being taken away.

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#20
In reply to #18

Re: Shortcuiting the Solar PV Array

07/20/2017 7:28 PM

Yes, all the energy comes from the sunshine.

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#22
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Re: Shortcuiting the Solar PV Array

07/21/2017 8:41 AM

Now all we need is a bullshine converter. Grandma used to use cowchips in her wood stove to cook biscuits. Buttered biscuit, anyone?

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#24

Re: Shortcuiting the Solar PV Array

07/21/2017 5:50 PM

21 modules rated at 315 W each connected in series?

These modules typically produce over 50 V and several amps, and you want to know if damage is likely by short circuiting?

Are all the cells in each module well balanced? How well?

Are all the modules well balanced? How well?

Ignore anyone who has overlooked the resistance in the short circuit.

If any module or cell is not working as well as the rest, it can be the largest resistance in the circuit. Most of the power will become heat in that cell. The cell need not even be defective or normally unbalanced...perhaps your head just happens to be shading that small area as you wonder about the effects of short circuiting.

.

The glass cover could break, the solder might become fluid, the anti reflection coating might be damaged, the encapsulation might be compromised, the cell might be damaged and become a weak producer creating a continual hot spot problem going forward, etc.

.

In short, abandon all hope. Better hope you can unload these for cheap on some sucker and start with some fresh ones.

.

.

How much would you take to get them off your hands?

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#25
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Re: Shortcuiting the Solar PV Array

07/24/2017 3:25 AM

<...the resistance in the short circuit...> Please explain what this is?

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#27
In reply to #25

Re: Shortcuiting the Solar PV Array

07/25/2017 3:31 AM

Do you have any solar cells comprised of superconducting material and kept at the appropriate temperature to behave as such?

So, there is resistance in the real circuit, no?

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#26
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Re: Shortcuiting the Solar PV Array

07/24/2017 9:40 AM

Not only that, but according to NFPA 70E, he is artificially creating an arc flash hazard by short-circuiting if in sunlight.

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#28

Re: Shortcuiting the Solar PV Array

07/25/2017 10:27 AM

It's interesting that there is so much basic disagreement here. It's also surprising how soft the positions taken seem to be.

Breaking the question down, the first question is would a single panel be harmed by short circuiting the output? Assuming the panel is not a commercial defect, the answer has to be no. The current will flow, but the voltage will collapse. The total power dissipated in the panel is still only the product of the insolation and the area illuminated. There is very little power in the circuit, so the problem of parallel junctions failing to share the power dissipation seems implausible.

Extending the answer to the series string does nothing to change the total current in the loop. So the answer, as applied to any single panel in the string, remains the same (again, assuming that the string consists of commercially matched panels).

However, if the string contains defective units or consists of mismatched panels, who's to say what might happen?

The panels on my roof each use micro-inverters, so all the outputs are connected in parallel, and each array is paralleled again in the combiner box, that that AC is paralleled across the house mains. The DC doesn't extend past the mounting rails.

FWIW, it's been a long time since I pulled a 750V 8A arc. I've gotta ask the OP: did you pull the positive or negative lead from the busbar, and how hot did the wire become?

Ciao

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