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Safety while connecting HV Solar String
#1
I want to connect six 42V VoC solar panels in one serial string to fuses and inverter.

What do I need to do to be safe? We're dealing with over 250V wich could produce sparks or is dangerous to touch, am I right?

Or is there no danger at all? Im really a newbie and everything you know could be interesting to me.
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#2
While there is no load no current must flow, so you must connect every panel of the string to each other, end positive and negative must be connected to the inverter or main switch beeing in off position, only after all connections are made an safe you must switch on.
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#3
To add, if you touch both Pos and Neg of the panels after 2 more connected in series, you'll be the load. Treat it as if you are connected a bunch of batteries together and as lethal as HV house power. Solar panel power "can" kill you.

You should be using combiner boxes so you can disconnect each panel in the series. Then after all connections are made, turn all the switches on.
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#4
So is it a must have to use such a combiner box? Or can I just connect without touching the connectors?
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#5
(06-02-2019, 12:36 PM)Korishan Wrote: You should be using combiner boxes so you can disconnect each panel in the series.


I've never seen a combiner box for evey panel in the serie, that means to have two cables from every panel to the box, normally with panels in series you connect positive from one panel to negative of the next or viceversa.

Combiner boxes are for when you have more tan one array of panel in series and you want to paralelize or control separatelly every array not for every single panel in the serie.

Having said that, even if your inverter have a switch for solar input is a good idea have a breaker before the input so you can isolate the solar cables if you have to disconnect them from the inverter, or if you have DC fuses you can use them to disconnect the panels, use some device you can disconnect the power coming from panels without having to go to the roof to disconnect one mc4 connector while the system is ON. Search for DC breaker or DC isolator, there are DC isolators with mc4 connectors so it is easy to mount.
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#6
Connect them during the Night when There is No Sun. Make sure to have a breaker suitable for it so you during the day can turn Them on and off.

IF you do it during the day proper gloves are a Wise investment for DIY people
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#7
250VDC will easily kill you, &/or make you jump & loose footing & fall.
Asking this question means you do not understand the danger!
Use multiple safe processes, eg:
+ always consider how any voltage could flow, eg cable via you to something else like grounded frame/rail or metal roof or roof pipe, guttering, flashing
+ use electrical rated gloves
+ leave all switches, breakers & isolators open until last
+ fit all connectors to panel cables before joining any connectors
+ leave one of more connectors on roof open
+ work only in dry conditions
+ cover that panels with heavy blankets or multiple cloth tarps or work at night so there's no/lower voltage on them
+ join wires/connectors only when all other cabling is finished
+ don't rush anything, you always end up regretting it.
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#8
(06-02-2019, 05:26 PM)jesusangel Wrote:
(06-02-2019, 12:36 PM)Korishan Wrote: You should be using combiner boxes so you can disconnect each panel in the series.
I've never seen a combiner box for evey panel in the serie, that means to have two cables from every panel to the box, normally with panels in series you connect positive from one panel to negative of the next or viceversa.

Combiner boxes are for when you have more tan one array of panel in series and you want to paralelize or control separatelly every array not for every single panel in the serie.

Agreed. I was actually thinking about the MC4 connectors. That way one doesn't have to actually touch the electrical wire to make the connections. I'll blame my mistype on not having my cup of java yet Tongue


(06-03-2019, 12:02 AM)Redpacket Wrote: ....
+ leave all switches, breakers & isolators open until last
+ don't rush anything, you always end up regretting it.

And I'll add:
+ check everything twice, if not thrice to verify everything is connected properly before turning "anything" on
Proceed with caution. Knowledge is Power! Literally! Cool 
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#9
(06-03-2019, 12:02 AM)Redpacket Wrote: 250VDC will easily kill you, &/or make you jump & loose footing & fall.
Asking this question means you do not understand the danger!
Use multiple safe processes, eg:
+ always consider how any voltage could flow, eg cable via you to something else like grounded frame/rail or metal roof or roof pipe, guttering, flashing
+ use electrical rated gloves
+ leave all switches, breakers & isolators open until last
+ fit all connectors to panel cables before joining any connectors
+ leave one of more connectors on roof open
+ work only in dry conditions
+ cover that panels with heavy blankets or multiple cloth tarps or work at night so there's no/lower voltage on them
+ join wires/connectors only when all other cabling is finished
+ don't rush anything, you always end up regretting it.

Oh, I do understand the danger of 250V. This is why I am asking. What still confuses me is the way the solar panels work. This no load, no current thing is still strange for me...

But these were the things I wanted to know. I did know that you can do it in the night or put some blankets over. But never seen anyone doing it. So I wanted to know how it is done in real World.

(06-03-2019, 12:27 AM)Korishan Wrote: Agreed. I was actually thinking about the MC4 connectors. That way one doesn't have to actually touch the electrical wire to make the connections. I'll blame my mistype on not having my cup of java yet Tongue

I will for sure have these connectors.
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#10
Also this is 250v DC we are talking about here. 240v AC hurts, it might kill you, it may make you jump up and down. 250v DC will grab you and kill you dead!
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