Fusing solar panel cables

[George94]

I think I have worked out what Graham means by "down the line". And he's absolutely right to be concerned.

 

Here is the scenario. During a gale, an electricity pylon on the side of a canal topples over and the power lines fall across the middle of a narrow boat, just where the 100V cable emerges from the side of the panel.

 

This causes a massive current to flow for a moment down the cable, but before it can do any damage, the fuse that was placed there on Graham's advice melts and saves the solar charge controller (and the boat's occupants) from injury or death.

 

These kinds of accident are becoming increasingly common as global warming takes its toll. I think we should all heed Graham's warnings, and fit fuses wherever we see a bit of un-fused line. That includes washing lines, because during an electrical storm a wet line can be come conductive.

 

Thank you, Graham. You may have encountered some hostility from certain quarters, but I for one value your input enormously.

[WotEver]

[Nickhlx]

Not sure whether "Isolators everywhere" is a bit of an exaggeration Our house systems don't have "Isolators everywhere", just a mains isolator, and an isolator for each string. The spec of what and how many isolators are required is laid down in the regs. They are not "scattered everywhere" which gives the impression that they have been haphazardly installed, thinking "the more the merrier"...

[WotEver]

I don't believe Dan meant 'everywhere' to be taken literally. I know I didn't.

 

There is an isolator on the input and output of the inverter in the loft, and one feeding the solar meter, so 3 in total.

 

No fuses though.

 

Tony

 

edited for sense

Edited December 16, 2015 by WotEver

[Graham.m]

For a starting point stop thinking fuse, think circuit breaker, they are capable of operating at closer tolerances and faster.

 

Several people have said PV panels are current devices and there cannot supply any greater current than there normal output. That is a simplistic view. Under fault conditions the panels can produce higher currents.

 

The other aspect is Isolators, not people have not scattered them like confetti care, thought and experience of faults etc that have happened in the past.

 

I think most of you think solar panels have been around for only a short time. Not true they have been around for over 20 years to my knowledge, and a version was around in the 1960s. So the knowledge that lead to the regs is based on years of knowledge.

[WotEver]

Several people have said PV panels are current devices and there cannot supply any greater current than there normal output. That is a simplistic view. Under fault conditions the panels can produce higher currents.

 

Yes,up to a whole 10% more.

[Graham.m]

I don't believe Dan meant 'everywhere' to be taken literally. I know I didn't.

 

There is an isolator on the input and output of the inverter in the loft, and one feeding the solar meter, so 3 in total.

 

No fuses though.

 

Tony

 

edited for sense

One thing I suspect you done know is the negative from the panels is earthed.

 

Also and possibly yours are not the panels on the roof are not earthed, they should be.

[WotEver]

Oh, and max current is with voltage nearasdammit 0V.

 

Of course, you will know better, so please show us the data to support your positon.

One thing I suspect you done know is the negative from the panels is earthed.

Also and possibly yours are not the panels on the roof are not earthed, they should be.

 

Yet more irrelevancies thrown out as a smoke screen. There's still no fuse or mcb on the panel outputs.

Edited December 16, 2015 by WotEver

[DHutch]

Not sure whether "Isolators everywhere" is a bit of an exaggeration...

I don't believe Dan meant 'everywhere' to be taken literally....

It would have perhaps have been better to say 'a large number of isolators, fitted in any location it would be reasonable for one to be fitted, and in more locations than electrically required for safe isolation of all components' but the overal meaning is similar and the location of the isolators was also detailed.

 

They are certainly not loosely scattered over the floor, nor chocker block floor to ceiling!

 

 

 

Daniel

[WotEver]

Lol

[DHutch]

Slightly interestingly as a small digression, the output from the solar inverter etc. joins the garage consumer unit on the supply side of the master switch. So said switch isoloates the garage light and power circuit, but not the panels.

 

The consumer unit is supplied by an sp MCB in the main house consumer unit, which has a single up front RCD.

 

I would have preferred the garage to have come off a switched fuse before the house RCD and have had its own RCD in the garage, but life is short and for what we use it for its not been an issue to date.

 

 

Daniel

[John V]

For a starting point stop thinking fuse, think circuit breaker, they are capable of operating at closer tolerances and faster.

 

Several people have said PV panels are current devices and there cannot supply any greater current than there normal output. That is a simplistic view. Under fault conditions the panels can produce higher currents.

 

 

incorrect, circuit breakers (even S curve) are significantly slower and of higher tolerance than the best fuses (semiconductor)

 

 

edit to replace lower with higher.....I knew what I meant dammit

Edited December 16, 2015 by John V

[DHutch]

incorrect, circuit breakers (even S curve) are significantly slower and of higher tolerance than the best fuses (semiconductor)

I was waiting for that post!...

[WotEver]

 

edit to replace lower with higher.....I knew what I meant dammit

 

Should have used 'wider'

[Graham.m]

Slightly interestingly as a small digression, the output from the solar inverter etc. joins the garage consumer unit on the supply side of the master switch. So said switch isoloates the garage light and power circuit, but not the panels.

 

The consumer unit is supplied by an sp MCB in the main house consumer unit, which has a single up front RCD.

 

I would have preferred the garage to have come off a switched fuse before the house RCD and have had its own RCD in the garage, but life is short and for what we use it for its not been an issue to date.

 

 

Daniel

 

daniel,

 

If I have understood correctly what you have written, the AC supply from the inverter is wired to the supply side of the garage consumer unit, which in turn is supplied by an MCB from the main consumer unit.

 

No mention of an Isolator between the inverter and the connection to the garage consumer unit

 

Also it should not be a MCB it should be a 30mA RCBO for the PV only. I only know that because they had to come back and change mine as the original installer incorrectly installed it and the company's QA guy spotted it on inspection, he also spotted the panels were not earthed and that was done as well.

 

incorrect, circuit breakers (even S curve) are significantly slower and of higher tolerance than the best fuses (semiconductor)

 

 

edit to replace lower with higher.....I knew what I meant dammit

 

But they are faster etc than standard wired fuses

[matty40s]

You appear to have missed yet another correction to one of your incorrect spoutings grahame...

[nicknorman]

You appear to have missed yet another correction to one of your incorrect spoutings grahame...

Out of interest Matty, do you know if there are any applicable standards for boat solar installation or does it fall between the IEEE regs that don't apply to boats, and the BSS / ISOs that don't really cover it?

[DHutch]

Daniel

 

If I have understood correctly what you have written, the AC supply from the inverter is wired to the supply side of the garage consumer unit, which in turn is supplied by an MCB from the main consumer unit.

 

Yes.

No mention of an Isolator between the inverter and the connection to the garage consumer unit.

It has been mentioned several times, and photos supplied. There are three methods of isolation between the two.

 

Daniel

[Graham.m]

Yes.

 

Well maybe a conversation with the supplier as this is a grid linked installation

[DHutch]

Well maybe a conversation with the supplier as this is a grid linked installation

Your post crossed with the second half of mine, however...

Inverter in the attic, with isolators both sides.

 

AC consumer unit, with an isolator between the cable from the inverter and the meter, and then an RCD+MCB between the meter and consumer unit.

 

 

Daniel

[matty40s]

Out of interest Matty, do you know if there are any applicable standards for boat solar installation or does it fall between the IEEE regs that don't apply to boats, and the BSS / ISOs that don't really cover it?

It falls outside, being an aftermarket addition in the main, and operating at relatively low voltages until very recent improvements in solar panel/mppt technology.

Where boats start to use multiple panels of a domestic size, the installations are still really regulated by the installers own 24/12v boat electrical knowledge and need for reputation to remain good.

Wiring sizes and distance for voltage drop, good connections, correct fusing, reliable and fit for purpose kit( even Bimble were selling a kit earlier in the year that exceeded safe parameters), are all as important as neat wiring and secure brackets.

 

I have seen and corrected a couple of installs this year on newly bought London bound boats that were laughable in their inept installation.

Edited December 16, 2015 by matty40s

[WotEver]

.

 

Edited December 16, 2015 by WotEver

[nicknorman]

It falls outside, being an aftermarket addition in the main, and operating at relatively low voltages until very recent improvements in solar panel/mppt technology.

Where boats start to use multiple panels of a domestic size, the installations are still really regulated by the installers own 24/12v boat electrical knowledge and need for reputation to remain good.

Wiring sizes and distance for voltage drop, good connections, correct fusing, reliable and fit for purpose kit( even Bimble were selling a kit earlier in the year that exceeded safe parameters), are all as important as neat wiring and secure brackets.

I have seen and corrected a couple of installs this year on newly bought London bound boats that were laughable in their inept installation.

Ta - so just down to good practice and common sense then.

[cuthound]

Ta - so just down to good practice and common sense then.

Both pretty rare these days

[Chewbacka]

Out of interest Matty, do you know if there are any applicable standards for boat solar installation or does it fall between the IEEE regs that don't apply to boats, and the BSS / ISOs that don't really cover it?

Though not being Matty, I think this is the situation as regards regulations.

Upto a MAX of 50v DC then BS EN ISO 10133:2012 small craft electrical systems DC applies.

For DC voltages higher than 50V would be covered by - I think - IEC60092