Quick one: unused solar panel on the roof, better short or open circuit?

[Zucca]

Hi,

my life is a mess. I just installed solar panels on the roof but the rest of the system is still work in progress....
It's a long story...

According to what I know solar panels act like current pumps, so it would be better for them to short + and - together to let the current flow....
otherwise the current is flowing to the internal resistance...

Now, to minimize performance degradation I would assume a solar panel is happier with the output shorted rather than open...

If you know more than me about solar panels please leave a comment below, I would like to know if I am missing something.

Should I short the + - strings coming down the roof if I do not use the solar panels on the roof (yet)?

thanks in advance!

 

[Q-Dog]

Just leave them unplugged. Nothing will happen.

 

[meetyg]

Maybe just seal the end of the leads with some electricians tape. But leave them unshorted.

 

[timselectric]

Open and protected.

 

[Q-Dog]

You only need to leave one connection open. If you plug the panels together in their final configuration you don't need to protect all of the ends, just the open connections. (I would go all the way to the disconnect, but that's just me not liking to do things twice) Just don't leave any bare wire ends

 

[chrisski]

You could weather protect the MC-4 connectors with a dust cap.

I can;t find my exact purchase, but I bought MC4 Dust Covers just like this 5 Pack of Male and female covers:

 

[Zucca]

Thanks!

they are wired and the panels connectors are safe!
You guys are pulling in the direction of leaving them open....

I still think that the panels will suffers less in a shorted circuit condition...

ohh, I have to admit I wanted to hear as many opinions as possible... so forgive me but...
See here at the EEVBlog
https://www.eevblog.com/forum/renew...-on-the-roof-better-short-or-open-circuit/50/

kind of little keyboard war there....

 

[webbbn]

I doubt there's any significant difference, but if you're concerned, put an appropriate resistor across the wires. Let that dissipate any current if necessary.

 

[timselectric]

If it were actually better to have the panels shorted, when not in use. The manufacturer would ship them that way. And provide instructions to keep them shorted, until placed into a working system.
After all, the manufacturers have the most interest in the longevity of the panels life.

 

[Kenny_]

Do not short. Just leave open.

 

[SeaGal]

You asked...

Should I short the + - strings coming down the roof if I do not use the solar panels on the roof (yet)?
thanks in advance!

Then say...

You guys are pulling in the direction of leaving them open....
I still think that the panels will suffers less in a shorted circuit condition...

I guess you are a troll, but if you already had those strong views then just do you own thing and don't waste everyone's time giving you their thoughtful input

 

[Supervstech]

Thanks!

they are wired and the panels connectors are safe!
You guys are pulling in the direction of leaving them open....

I still think that the panels will suffers less in a shorted circuit condition...

ohh, I have to admit I wanted to hear as many opinions as possible... so forgive me but...
See here at the EEVBlog
https://www.eevblog.com/forum/renew...-on-the-roof-better-short-or-open-circuit/50/

kind of little keyboard war there....

What kind of timeframe are we thinking of leaving the panels on the roof unused? I mean... why?

None of us have studied the lifespan of panels stored in full sun... we USE OUR PANELS!
What difference would gathering opinions be to your question?
You apparently want to know which is best.
Look for studies that have tested the lifespan. I will wait here, use my panels and not worry about it.

 

[efficientPV]

Every solar panel has one or more weaker cells. Shorting a panel causes the good cells to gang up on the weak ones. This overheats these and stresses them. Over time this leads to damage. There are FLIR photos that shows this happening.

 

[Zucca]

No I am not a troll (me a troll? that's the first time it happens... it's funny), I just want to understand the better how solar panels works by making the right decision in my strange situation.

timselectric​

efficientPV​

webbbn​

Thanks at least you provided a reason in your suggestions.

What kind of timeframe are we thinking of leaving the panels on the roof unused? I mean... why?

Installation was done beginning in August, and until 20th September I can't connect the inverters because I will be on vacation or did not have time.
Two kids, 40 hours/week job plus wife that is pushing to get other projects done. I need a day with 48 hours.

Look for studies that have tested the lifespan. I will wait here, use my panels and not worry about it.

That's the point, can't find anything related to degradation in short circuit. In open state there is something out there
https://www.sciencedirect.com/science/article/pii/S2211379716301280

had those strong views

I just studied https://www.pveducation.org/ and it seems to me that a solar cell is similar to a current source... and a current source needs to be short circuited to be happy. Feel free to call this a strong view.

Anyway I did not want to irritate or increase the blood pressure to anyone. I apologize without knowing what I did wrong.

 

[Crowz]

Well I never gave this much thought but I had 2 100 watt renogy panels I left unhooked from anything other than dummy plugs I made from jb welding the ends of bad mc4 connectors that I plugged into them to keep water out.

They sat in the sun for 6 years before I moved them to the new house since they are 12 volts and low amperage which caused them not to play well with the large 24 volt panels I had got to replace them with.



This is a pic of them on the awning of my new house and they work fine from what I can tell. They make the right amount of power according to the display on the 4215bn controller they are hooked to.

So yes leaving them unplugged in direct sunlight isn't a problem. I do recommend plugging dummy mc4 connectors into the cable ends to keep out moisture and prevent corrosion. At least tape up the ends or something.

 

[Tomthumb62]

If you’re that worried about it, just cover the panel with a blanket or cardboard so it can’t see the sun.