Lightning Strikes

[Potemkin Villager]

Very close by strike here recently in mid afternoon as I was taking my siesta. Sufficiently loud explosive bang to make me nearly jump out of the bed and took several hours for the effect of the adrenaline rush to subside. We got off relatively lightly as my better half wisely insisted we unplug sensitive devices like telly, fibre modem, satellite receiver and computer etc after a lesser strike a few hours before. All we suffered was a zapped landline telephone and damaged copper line which is still being repaired.

Our next door neighbours were not so lucky as Mr Know it All bravely insisted on not missing the afternoon sport on the telly. Not only were their telly and sound bar zapped but several mains plugs shattered and sprayed the near vicinity with shrapnel and the cut out fuse on their mains supply blew as well!

Supply here is at the periphery of an extensive overhead distribution/lightning antenna system. Nearest 110/20 kv sub station is about 6 miles away and the domestic supplies for about 8 houses is two wire from a pole mounted transformer about 150 metres away. So each property has it's own earth rod (generally old and probably not that effective especially in dry weather).

The thing that puzzles me is why our neighbours were so much more affected than us. It also makes we wonder how many PV grid tie inverters are susceptible to this sort of onslaught as presumably lightning finds roof mounted PV panels quite tasty.

[PS_RalphW]

My parents were on holiday in Paris in the 90s (the only time in her life my mum went abroad) when lightning struck the step down transformer in their village. Pretty much every device connected to the mains in the village was blown. My dad being a firm believer in electric safety he had unplugged everything except the vcr and the electric clock in their kitchen oven.

My grid tied hybrid inverter which was installed last week has its own deep earth rod (actually a 50cm earth disc 60cm down) to provide a true earth in order to provide an emergency power circuit in the event of a grid failure. All new pv systems have surge protection circuits on the panel wiring against lightning induced voltage surges.

https://www.youtube.com/watch?v=Eprgq3lrgwg

[Potemkin Villager]

My parents were on holiday in Paris in the 90s (the only time in her life my mum went abroad) when lightning struck the step down transformer in their village. Pretty much every device connected to the mains in the village was blown. My dad being a firm believer in electric safety he had unplugged everything except the vcr and the electric clock in their kitchen oven.

My grid tied hybrid inverter which was installed last week has its own deep earth rod (actually a 50cm earth disc 60cm down) to provide a true earth in order to provide an emergency power circuit in the event of a grid failure. All new pv systems have surge protection circuits on the panel wiring against lightning induced voltage surges.

https://www.youtube.com/watch?v=Eprgq3lrgwg

So there are a lot of pv systems out there without surge protection.

I was most impressed, and a little terrified, as an 8 year old witnessing a severe lightning storm, on a family holiday, from inside a Faraday Cage in the form of a caravan. We were parked up near the transmission switchyard of the hydro electric station near Ballyshannon on the River Erne. It lasted about 20 minutes and it was awesome watching the lightning traveling along the overhead lines and I am not sure I totally believed my da saying we were safe inside the caravan!

The voltage surge protection I guess are fairly chunky varistors but these can only absorb a certain amount of energy before popping
so would maybe need regular testing in lightning prone areas. Is there similar protection on the mains supply side of the inverter as well?

The installation and kit shown in the video seems rather overengineered and I am not sure how wise it is exposing all that kit to the elements. I get the feeling the installers did not fully appreciate the finer points of the features of the equipment and were learning courtesy of their customer. Cowboy installers are a big problem in this part of the world as PV is now seen to be the latest double glazing. Working on the DC side seems potentially quite dangerous and one wonders what real recourse customers have if some of the complex, and probably difficult to repair, electronics gives up the ghost.

[BritDownUnder]

I would have thought it would be easier to put a lightning conductor on top of the house above the level of the solar panels.

I had a tour of the solar farm at Darwin Airport in Australia and they said that they used wires strung above and across the panels as lightning conductors but had the unexpected side effect of birds sitting on the wires and pooping on the panels.

There are issues in industrial systems of control systems being damaged by lightning strikes if they are earthed to the nearest part of the earth grid as the very high currents generated in earth grids by a lightning strike can cause voltages to rise in parts of an earthing system to be enough to damage rather fragile control systems (i.e. around 100 Volts). I think it's called ground potential rise. To get around this all parts of a control system are generally earthed to just one point on the earthing grid.

[Potemkin Villager]

I had a tour of the solar farm at Darwin Airport in Australia and they said that they used wires strung above and across the panels as lightning conductors but had the unexpected side effect of birds sitting on the wires and pooping on the panels.

Don't you just love unintended consequences.

The overhead distribution and PME earthing around here, and a very thin soil level, usually has the effect of popping our domestic consumer unit
RCD when there are nearby lightning strikes. Weirdly our power stayed on without interruption this time and when I switched on an LED light
seconds after their was furious flickering for about 5 seconds which died away.