Morning everyone.

This past Saturday we had a lightning strike. A few seconds before the zap, there was an audible crackle from the plugs / wiring.

The inverter reported a DC over_current event and reset itself after a few minutes. 

Earth leakage did not trip.

My network switch was the only electrical device that was destroyed. Note that its a PoE switch and does have devices externally mounted (cameras and wifi access point). Can't confirm if the linked devices are dead.

I do have AC and DC Phoenix Contact surge protectors installed and are still functional.

 

1. How do I protect the replacement switch / devices in the future? The plug is earthed and allegedly working correctly

2. Why did earth leakage not trip?

3. How can I confirm that the surge protection was installed correctly?

 

Thanks!

Same thing happened to me and would also like to know. 

I have a lightning protection system and it still partially knocked out my network switch (poe functionality not working anymore but network is still working) and my HDMI recievers are all dead. Everything else is ok.

Ensure that everything is properly earthed.

Install arrestors on AC en DC side.

Nothing is Lightning proof.

 

Only 100% lightning protection is the distance between the device plug and the wall outlet. 
Low voltage devices like Routers and Network switches are particularly prone to surges.
As a matter of routine I unplug everything when the storms and lightning are near, including shutting down my solar system and switching off all trip switches, including the MCB for the Solar panel DC feed.
 

Edited October 26, 20223 yr by zsde

The attack surface with PV is especially wide, bear in mind in that with the modern high frequency transformerless designs that your pv negative and your grid neutral are  connected. As a qualitative maintenance measure replace pv surge protection once every 5 years at least. 

We have a guard hut outside our property and their network switch got fried as well. Not sure if its linked to the issue I experienced, as they are connected via ethernet, as well as shared mains power (municipal feed only, not through inverter). I think we did get lucky with the AC and DC surge protection we had installed last week!

I did read on another forum where a guy had his brand new and sealed Netgear equipment taken out by lightning storms - I assume through EMP type interference. Insane!

Yeah, I have seen a couple inverters returned after lightning strikes and @BritishRacingGreencalled it. Lightning strikes are devastating regardless of how well prepared you are, best thing you can do is get a surge arrestor on PV, AC in and AC out. Put fuses on the DC line incase that's where the strike enters the system and minimize the damage. At the end of the day its an acceptable loss to have a network switch fry, but a burnt out inverter is going to cost a whole lot more...

 

I will advise looking into a PoE surge protector, they do exists and while not perfect they are your best bet. Also, keep in mind surge arrestors etc can only clear a few faults. Eventually the arrestor will stop working and will need replacement, it the nature of the beast and clearing massive spikes does slowly wear them down over time.

4 hours ago, BritishRacingGreen said:

bear in mind in that with the modern high frequency transformerless designs that your pv negative and your grid neutral are  connected.

As in, they are at the same potential some of the time. But when generating the negative half of the AC output, neutral/earth is connected to the positive end of the DC bus, so the PV negative terminal is then negative by hundreds of volts with respect to earth. I don't know if that extra ≈half kilovolt makes much difference attracting the lightning leaders, but it may do.

I believe that this would be the case for all transformerless inverter designs, grid tie or off-grid, as long as they have a high voltage Solar Charge Controller.

To be truthful @jaques ester is very right, nothing is truly 100% lightning proof, best we can do is either, switch off switches or ensure with the help of the installer that adequate protection systems exist in your system including:

* Lightning rods/arrestors for the panels

* Surge Protection devices with either fuses or sacrificial SPDs

 

All these should be on both the AC and DC side going to the inverter. See also my other recommendation: 

https://www.amazon.com/MidNite-Solar-Protection-Device-MNSPD-300-AC/dp/B00A6XHOS2

19 hours ago, Coulomb said:

As in, they are at the same potential some of the time. But when generating the negative half of the AC output, neutral/earth is connected to the positive end of the DC bus, so the PV negative terminal is then negative by hundreds of volts with respect to earth. I don't know if that extra ≈half kilovolt makes much difference attracting the lightning leaders, but it may do.

I believe that this would be the case for all transformerless inverter designs, grid tie or off-grid, as long as they have a high voltage Solar Charge Controller.

yes , thank you for pointing that out . The neatra and live  is not on the dc bus , but on the ac bridge output , so yes it will be switched in and out as you've said .

On 2022/10/26 at 11:27 PM, Moffat said:

best we can do is either, switch off switches or...

One of the problems is that lightning ⚡🌩️tends to be disrespectful 👿 of "off" switches. 3 mm gap... you call that a gap? 😟

Unplug your surge protector during electrical storm, don’t just turn them off. Unplug all expensive electronic stuff.
 

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Edited November 6, 20223 yr by Gordons

The OP also asked why the earth leakage didn't trip, a earth leakage only trips when it measures 30mA or more traveling from AC live or neutral  to earth, in case where you stand barefoot and touch a live wire and the current flow through you.

Btw a EL is the only thing to protect you as a human, inside your DB. 

On 2022/10/27 at 5:30 PM, Coulomb said:

One of the problems is that lightning ⚡🌩️tends to be disrespectful 👿 of "off" switches. 3 mm gap... you call that a gap? 😟

A whole cow can be fried in that "3mm gap" 🥲 I guess disconnecting items would be recommended but then it also defeats the purpose of having a system which brings you into the dark ages during every storm and one has to resort to candles of lamps... but it is what it is.

@Scorp007I have a Axpert with the mppt running between 75v and 100v. The installer installed a surge arrestor with a Uc voltage of 385v- (Lear LS-DD10/1) to protect the inverter. Is this not to high. Would it be beter to use A Citel with Uc of 130v-. How do we calculate this value. I also want to get a surg arrestor for a Epever running at 64v to 80v. Thanks

On 2022/11/06 at 7:32 AM, Vaal said:

earth leakage only trips when it measures 30mA or more traveling from AC live or neutral  to earth

nope, it trips when there is an inbalance between live and neutral, both sides should carry the same current, else something is leaking to earth...

As for lightning, if you have a direct strike on your AC or DC conductors, pretty much everything will be toast that is even remotely connected to these conductors...

Networking equipment... try STP aka Shielded twisted pair and keep it in a metal conduit, which also should be earthed well, usually on the STP one side only gets grounded, I suppose the side that has access to a better ground point...

If you have to have PoE equipment outside, budget for replacement, the right thing would be to run fibre and source a more local power supply, indoors it should not be much of an issue.

Most people have conductors running out doors and not realising that a nearby strike, lets say 100m away can induce a serious amount of power in those outdoor conductors, be the LAN cables, DC cables between solar panels and MPPT input or what have you, that carries power in any way shape or form. You could go berserk with MOV's everywhere and they will protect you to a degree and may save some of your equipment, but also likely will need replacing on a regular basis and in case of a LAN cable, how many MOV's? 1 per pair or one per pair and 1 between each other pair, in other words one for pins 1 & 2, one for pins 3 & 6, one for pins 4 & 5 and one for pins 7 & 8 or those plus one for pin 1 and 3 another for pin 1 and 4 another for pin 1 and 7 and another for pin 3 and 4 and another for pin 3 and 7 ( I hope that covered most pairs...), still you should be running STP, problem is, I haven't seen decent STP for few years, they all try and sell you FTP, which is mylar/aluminium foil around your cable pairs with one very thin and weedy drain wire in there as well... best to consider fibre, its a pain and less common, but lightning won't touch the stuff...

9 hours ago, Chris Louw said:

Is this not to high. Would it be better to use A Citel with Uc of 130v-. How do we calculate this value.

Sorry, I'm no expert on lightning, in fact a victim of a nearby strike. 130 V seems quite reasonable to me.

Interesting stats during lightning storm on 15 October.  Just sharing the graphs of the power generated by the panels during the storm