Automated lightning protection idea?

[n2aws]

Hey all,

I've got an idea that I'd like some input/feedback on.

Background:
I live in an area with a *lot* of lightning. I've heard it referred to as "the lightning capital of the US" (not sure if it's just a claim, or legitimate). But over the years, I've had close proximity strikes twice that damaged equipment, and needed replacing. That said, I don't think I've ever had a direct strike.

I've got a solar inverter with battery backup wired to a critical loads panel. It's grid-tied, and I'd like it to remain grid-tied for a multitude of reasons that don't really matter for this post. Suffice it to say: 100% offgrid isn't an option I'd like to entertain.

Idea:
I was thinking about adding a normally closed contactor in place between the main panel, and the solar inverter. This would allow me to take the solar and critical loads panel "offgrid" easily.. but more importantly, in an automated fashion.

What do I mean by automated? Well.. I'm thinking about using a raspberry pi, and writing a script to hit an API of one of the various weather websites that shows lightning strikes over time. I suspect I could find a somewhat reliable site, and poll it. if there are any recent strikes within some distance of my location (I'd have to look up how far lighting can strike laterally, but for the sake of discussion, lets say 10 miles). So, any strikes within 10 miles in the last 15m, kill power to the contactor, and "disconnect" the grid from the inverter. Then, when the area is clear, energize the circuit, and reconnect the grid. This way, if I were to take another strike.. it wouldn't damage the inverters, charge controllers, or any of the "critical" electronics powered from the critical loads panel. However, the remaining electronics would still be vulnerable.

From there, It would be relatively easy to add other functionality.. like if I see signficant voltage rise or drop on the grid, disconnect it.. etc etc.

Is this an absurd idea? Do others think they'd find it useful if the project were to ever be built? etc. etc.


Feedback appreciated!

 

[timselectric]

I would just install a SPD and call it a day.
But I'm not saying that your idea is bad. I like simplicity.

 

[Bkord]

Lightning can come in from anywhere. From the power lines, phone line, ground wire, tree, air. Our church has a low voltage system in the attic. It has been hit 15 times, taking out only the low voltage equipment. I believe it enters through the attic and hits multiple audio, video, and lighting controls. It never affects the 120/240 system. It never affects equipment that does not have a wire in the attic. They had me install surge devices in every breaker panel, it did not help. I told them years ago we need lightning rods, but it never gets approved.

 

[KITROBASKIN]

Weren’t they talking about lightning strikes when it was said ‘there are no guarantees in life.’

 

[zanydroid]

I like it, seems quite reasonable unlike a lot of other lightning protection ideas we get around here related to unbonding your house.

In terms of the control intelligence, this sounds similar to the weather prediction functionality on PowerWall.

That said it’s hard to say whether you will get an advantage.

Did you already do layered SPDs? For reference in my low to zero lightning area I have three layers (low power) SPDs in front of my minisplit, and one to two layers in front of my microinverters.

Every subpanel gets a SPD and everything expensive enough gets a point of use SPD.

 

[n2aws]

I like it, seems quite reasonable unlike a lot of other lightning protection ideas we get around here related to unbonding your house.

In terms of the control intelligence, this sounds similar to the weather prediction functionality on PowerWall.

That said it’s hard to say whether you will get an advantage.

Did you already do layered SPDs? For reference in my low to zero lightning area I have three layers (low power) SPDs in front of my minisplit, and one to two layers in front of my microinverters.

Every subpanel gets a SPD and everything expensive enough gets a point of use SPD.

Yeah, I already take the standard precautions (layered SPD's, etc). I'm also a ham radio guy with a 72' tower that has a pretty solid lightning protection system.. As others mentioned in the thread, I know lightning can come in from anywhere.. But the only physical points of contact to anything on the protected loads panel, would be a wire from my main panel, to the inverter (unless the lightning happened to hit the solar array itself). so, my thinking is, physically isolating that connection is probably the safest way to do it. Now mind you, I realize that a lightning strike, the current may "jump the gap" in the contactor, but with all of the ham radio lightning stuff, I suspect there are a lot of more optimal ways to ground for it to travel, reducing the likelyhood.

As for keeping it simple, I'm normally a fan of that too. I wouldn't need to install anything else, and could just go flip the breaker if I happen to be around. I'm more interested in protecting from the 2 or 4am storms where I'm asleep.. or when I'm out of town.

 

[zanydroid]

OK, great. Just wanted to make sure you covered the low hanging thing (which may actually have comparable benefit).

I think you can get well above 50A if you get a big-ish industrial contactor, I use one from WEG for disconnecting my EV, and it is good to 50A. It's housed in a pretty large enclosure, like 6" or 8" deep. LOL.

Note that you need to factor in the % of loads that are inductive vs resistive when sizing contactors, since the ratings are multi-dimensional in that sense.

If you want to live on the expensive bleeding edge you could consider using an Eaton smart breaker instead of a contactor. Advantage would be packaging -- you get the WiFi API host, contactor, and OCPD in a 3 breaker space footprint. And maybe it has better isolation/interrupt rating than a contactor. Dunno. Maybe an EE or electrician will weigh in on that.

 

[n2aws]

OK, great. Just wanted to make sure you covered the low hanging thing (which may actually have comparable benefit).

I think you can get well above 50A if you get a big-ish industrial contactor, I use one from WEG for disconnecting my EV, and it is good to 50A. It's housed in a pretty large enclosure, like 6" or 8" deep. LOL.

Note that you need to factor in the % of loads that are inductive vs resistive when sizing contactors, since the ratings are multi-dimensional in that sense.

If you want to live on the expensive bleeding edge you could consider using an Eaton smart breaker instead of a contactor. Advantage would be packaging -- you get the WiFi API host, contactor, and OCPD in a 3 breaker space footprint. And maybe it has better isolation/interrupt rating than a contactor. Dunno. Maybe an EE or electrician will weigh in on that.

I'm not sure I'm familiar with the Eaton breaker. happen to have a name or link where I can read more? a quick internet search showed several options that.. doesn't help the person who is searching without knowing what he's looking for specifically.. lol

 

[zanydroid]

I'm not sure I'm familiar with the Eaton breaker. happen to have a name or link where I can read more? a quick internet search showed several options that.. doesn't help the person who is searching without knowing what he's looking for specifically.. lol

These things.

https://www.lowes.com/pd/Eaton-BR-Smart-Breaker-2P-50A/5013712447

Basically like a smart panel, except one circuit at a time

I’m not sure this is backfeed compatible though, a lot of breakers with circuitry assume power is coming from the bus side