Do I need surge arrestors on my battery inputs??

[crossy]

We live in a relatively high lightning area (central Thailand).

We have a big (100kA) surge suppressor on the incoming supply (overhead cables) and I have 40kA suppressors on the mains next to each of my two grid-tie inverters. There are also DC suppressors on the solar string inputs.

The whole lot is actually on our all-steel car port which has it's own grounding rods, everything is cross bonded to death.

I'm adding a grid-tie hybrid inverter for some UPS functionality (our genset is noisy and getting old) and to reduce our reliance on net-metering (disc meter goes backwards on export) which is technically illegal here (but everybody does it, the only consequence of getting caught is that they fit a no-reverse meter).

So, should I add suppressors to my 48V battery supply?? Batteries are about 6 feet from the inverter and everything is on steel racking.

Thoughts welcomed

 

[Samsonite801]

Sol-Ark (as an example of a robust EMP hardened system) makes EMP hardened kit along with EMP hardened option for their 12k inverters, and their kit only has you install suppressors on the solar run side. They don't indicate anything added to the battery side, so I wouldn't worry about it.

https://www.sol-ark.com/wp-content/uploads/2021/02/Indoor-12K-Manual-9-21-2020-Indoor.pdf (can search the doc for 'suppressor')

I personally haven't heard of using a suppressor on battery side of an inverter anyways, but perhaps it exists...

 

[crossy]

Sol-Ark (as an example of a robust EMP hardened system) makes EMP hardened kit along with EMP hardened option for their 12k inverters, and their kit only has you install suppressors on the solar run side. They don't indicate anything added to the battery side, so I wouldn't worry about it.

https://www.sol-ark.com/wp-content/uploads/2021/02/Indoor-12K-Manual-9-21-2020-Indoor.pdf (can search the doc for 'suppressor')

I personally haven't heard of using a suppressor on battery side of an inverter anyways, but perhaps it exists...

Yeah, me neither which is why I asked here, cables are short and in metallic enclosure I can't really imagine anything nasty getting picked up.

My biggest worry is actually the 20m aerial feed between the car port and the house, hence the overkill on the suppressors at both ends, they are a lot cheaper than new inverters.

 

[Samsonite801]

Yeah, me neither which is why I asked here, cables are short and in metallic enclosure I can't really imagine anything nasty getting picked up.

My biggest worry is actually the 20m aerial feed between the car port and the house, hence the overkill on the suppressors at both ends, they are a lot cheaper than new inverters.

Yeah and I don't know how much property you have, but I've heard some people who live in areas of frequent lighting, might put up a lighting rod in a remote location on their land a ways away from the house to help attract the lighting over there instead. This one lady I knew who lived in Canada had such setup and she swore by it, said it works...

 

[crossy]

There's a 'kin great cell-tower 200m away, didn't stop us taking a direct hit to the roof a while back

Luckily we have a steel roof structure which is (fortuitously rather than deliberately) bonded via the re-bar all the way to our 16m piles (we are on Bangkok clay). The roof steel actually measures as a better ground than our regulation 2.4m rod.

The only structural damage was a couple of ridge tiles, we did lose the satellite LNB and Wi-Max router both of which were outside the effective Faraday cage formed by our building steel.

 

[Samsonite801]

Well, it sounds like you are already pretty in-tune with your lighting characteristics and have a pretty good handle on how you need to handle it.

I have seen some people put lighting rods even on the roof of there houses before, I suppose one could put one on an opposite corner, farthest away from their electrical gear...

The faraday box effect seems pretty effective to help absorb the EMF and ground it... Well good luck on that going forward.

 

[crossy]

@Samsonite801 thanks for your assistance, I've not done a battery system before (all grid tie) hence my asking.

I'm not going to bother with suppressors on the battery (famous last words I suspect).

 

[Samsonite801]

@Samsonite801 thanks for your assistance, I've not done a battery system before (all grid tie) hence my asking.

I'm not going to bother with suppressors on the battery (famous last words I suspect).

But with DC breakers / fuses for sure!

 

[crossy]

But with DC breakers / fuses for sure!

Absolutely!!!

I've watched that YouTube about using AC breakers on DC!! (and that was just on the PV inputs, batteries would be a nightmare). People fail to understand just how much energy is tied up in even a 100Ah x 48V pack.

 

[Samsonite801]

Yeah I saw that video too, pretty nuts hehe... You know a DC welder runs around 35-85 volts and they strike an arc (high amps), and run beads of rod to fuse two pieces of metal together.

I'm not sure your budget, but on mine I bought a Midnight Classic DC box for the battery to inverter connection, since I plan to install a bunch of smaller DC breakers in it for DC loads (has knockouts and additional breaker slots on the side)...

I have 2 battery banks, so I got the X2 one, but they also have single (large) breaker enclosures too:

X2:

MidNite Solar MNDC175-X2 Mini DC Disconnect 175A Breaker | eBay

MidNite Solar Mini DC X2 Models Brochure. MidNite Solar MNDC-X2 Instruction Manual. Based on our Wide E-Panel chassis with a blank door, the MNDC175-X2 has a pair of 175A/125VDC battery breakers on each side for disconnecting two sources or loads and an earth ground buss bar.

www.ebay.com

Single:

Midnite Solar MNDC175 Mini DC Disconnect for sale online | eBay

Find many great new & used options and get the best deals for Midnite Solar MNDC175 Mini DC Disconnect at the best online prices at eBay! Free shipping for many products!

www.ebay.com

Or can just get the little bolt-flange mount style breakers like a lot of people use (Eaton / Bussman or Blue Sea Systems style or whatever)...

Examples:

Amazon.com

Amazon.com