Switched off solar inverter to clean, how restart?

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Re: Switched off solar inverter to clean, how restart?

Postby australsolarier » Wed Dec 26, 2018 8:29 am

it seems to me, to break the fuses, there was a bit more done than just cleaning around the inverter. even if the strings are short circuited it shouldn't blow the fuse.
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Re: Switched off solar inverter to clean, how restart?

Postby Araich » Wed Dec 26, 2018 8:33 am

I think perhaps I blew them by switching the DC isolator beside the inverter on and off under load... maybe. My memory is that I turned off the AC isolator beside the inverter, cleaned (not getting it wet), then tried to turn it back on and got nothing - but maybe did not wait a couple of minutes, then started messing with all the switches.
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Re: Switched off solar inverter to clean, how restart?

Postby Araich » Wed Dec 26, 2018 9:20 am

I did get some water on the isolator switches and possibly a splash under the inverter - where I notice there are DC lines that terminate perhaps for stringing inverters together? This may have cause a short. I was pretty careful. I thought the switches were waterproof.
I've read that switching the DC isolators under load can blow fuses, true?
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Re: Switched off solar inverter to clean, how restart?

Postby davidg » Wed Dec 26, 2018 10:13 am

australsolarier wrote:even if the strings are short circuited it shouldn't blow the fuse.

I would agree with this mostly.
Fuses circuit breakers only need to be install when there is 3 strings or more going to the same input/mppt. The reason is Solar PV is a current limited source however a Panels typically does have current limit of about 15A.

If you had 3 strings of panels in parallel and the Isc of each string is say 8.1a. Then if a short circuit developed in one string the other 2 strings have the ability to exceed the typical 15a rating of the faulty string, this is the reason there should be circuit protection in 3 strings or more that are in parallel. If this is not the case then it is pretty much a waste of time installing circuit protection in 2 parallel strings or less as the circuit protection should never fail . However if there is a decent amount external heat applied (sun and or high ambient temp) circuit protection may well fail if it is too conservative even though there is no actual fault.
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Re: Switched off solar inverter to clean, how restart?

Postby Araich » Wed Dec 26, 2018 12:30 pm

2 strings of 7 panels one side
1 x 6 panels other
20 panels total 4.9kw
Attachments
20_panels.jpg
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Re: Switched off solar inverter to clean, how restart?

Postby australsolarier » Sat Dec 29, 2018 8:20 am

davidg,
naturally you are totally correct with fuses and parallel strings.
however, my contribution was related to araich's fuses blowing, to the thread he started, in context what was said before, not an advice to everybody else's systems, directed specifically to araich's problem where there are only 2 strings and fuses involved.
(as compared to my groups that have up to 9 strings going into a charge controller, or possibly your installation, or other people's installations. however your contribution is greatly valued in general understanding of why paralleling more than 2 arrays should be fused. most diy'ers do not understand that.)

going back to araich , it is still a mystery to me why those fuses should blow, just because he "cleaned around the inverter". and it is a mystery why he turned off the system. that is why i suspect, guess, there is more to it than just cleaning.
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Re: Switched off solar inverter to clean, how restart?

Postby Araich » Sat Dec 29, 2018 8:44 am

I totally regret turning it off. The inverter is on a wall in the corner and dirt and leaves had accumulated on the decking and wall around it where I was renovating, so I was hosing the ground and wall and then pretty close to the inverter, so I thought it prudent to switch off the AC isolator (doh). Water splashed on the DC and AC isolator switches but not the inverter and only a splash. After a few hours I turned the AC Isolator back on but when it didn't immediately light up, I started playing with the DC switches. This I suspect is how I did it.

I still have not gotten fuses to replace yet so who knows if it is worse than me repeatedly turning the DC isolator switches on and off.
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Re: Switched off solar inverter to clean, how restart?

Postby australsolarier » Sat Dec 29, 2018 10:27 am

what the inverter is on the floor?
if it is, i am pretty sure it is against regulations.
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Re: Switched off solar inverter to clean, how restart?

Postby Araich » Sat Dec 29, 2018 12:25 pm

Araich wrote:IThe inverter is on a wall in the corner and dirt and leaves had accumulated ...
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Re: Switched off solar inverter to clean, how restart?

Postby australsolarier » Sat Dec 29, 2018 1:27 pm

meaning, if the inverter is 1.5 above the floor, the leaves really have accumulated!!!!!!!!
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