lightning protection

[mark]

My off-grid system is in a very active lightning strike area.  I have all equipment connected with bare #6 copper wire and multiple ground rods all connected together. (ground is so rocky that a rod can only be driven 4 feet). Delta lightning protection on PV combiner box, and on AC and DC circuits in panel.  I plan to add, or should I switch over to, Midnite solar arrestors?  Also is anything accomplished during a lightning storm by shutting down the PV breakers as well as turning off the inverter?  Any other suggestions to protect my system would be welcome.
Thanks

[niel]

i don't know too much about the deltas to say how they compare other than what midnight says. the guys can get more specific with specs. i won't tell you you need to throw away your deltas if you can add the midnight surge suppressors to them for the more the merrier. i can say the size of the midnight surge suppressors are bigger in size than the deltas and do have 2 blue leds for showing it's operational.

your efforts to shut things down and disconnecting is a good one, but remember that you are only breaking contact on one wire with a short jump to the on position. a strong voltage will overcome a small switch's gap and could still also travel the other wire leads. smaller damaging voltages could be thwarted enough by shutting it off or disconnecting and is to be viewed as another positive effort at preserving your equipment during said storms.

a faraday cage may be an option for your place that may allow charges to bypass rather than go through your home. one can only do one's best given circumstances and with 4ft of soil that's what you get to work with and is far better than only rocks. you have utilized multiple rods and tied them together (hopefully you had tied them underground) to gain further ground contact area so there's not much more you can do here without getting ridiculous. every effort is a plus, but remember that when it comes to lightning that there are no guarantees, only improving odds.

[SOLENTRICS]

Well Mark a four foot ground rod is okay. I have been working in the electrical field for over forty years. I have done systems where each point had to have a triangle grid consisting of three rods tied together, then it went to one rod and now a ground plate buried down two feet does the same. I have done substation, towers and large buildings and grounding is very important for lightning. A study that was done a few years ago changed the way we ground now in Canada. The study involve all types of grounding methods that industry uses was installed with current monitors to see which one passed more current showing a more effective ground path. The supprising results showed that a lighting strike does not travel deep in the earth like everyone thought, but flows horizontally just under the surface. The system with ten foot rods made no differance as when the strike hit the ground it immediatly flowed horizontally just under the surface. The only ground problem your can have is if you are in a desert type area where a low moisture content is present. I always ground everthing with the same #6 so all equipment, even the electrical panel can rise to the same potential which will inhibit current flow. Many systems that failled because of lightning and poor grounding had no more problems once grounding was upgraded and arresters installed. Even a strike that took place in the field near a home caused a a small fire in the television where the cable was connected but the electrical system c/w inverters  survived.

[TonyU]

As long as your grounding system is good (and that is KEY), you may want to add some additional/better surge protection.
The Delta units are designed for relatively high voltages, so they will let through quite a surge (on the order of a couple of kiloVolts) even as they are shunting that surge to ground.
You should have Surge Protection Devices (SPDs) on all of the different sub-systems that match the operating conditions.  For example, you should have an SPD for 120/240VAC on your backup generator line, an SPD for your PV that is designed/sized for the operating voltage (before it goes into your charge controller), an SPD for your battery (though a battery can act as a pretty good SPD itself) DC buss, and an SPD for your inverter AC output.



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Admin

[boB]

The Delta units are designed for relatively high voltages, so they will let through quite a surge (on the order of a couple of kiloVolts) even as they are shunting that surge to ground.

FYI,  The LA302 appears to  conduct, (arc over),  at around 6 to 7 kV as we have measured.

boB

[SOLENTRICS]

I did the same test and just under 7kv it jumps accross. I was discusted when Robin showed it to me as I have installed hundreds of these. Waiting for the new one to come.

[niel]

well at 7kv why bother having the deltas as the damage is already done long beforehand? that's almost like having nothing there. i guess a complete swap-out for the midnight spd is in order for everyone if you guys started shipping them out yet. that reminds me i still have one of the deltas inline i'll have to swap yet and i better do it before more bad weather comes.

fyi-the twister that was in pa you may have heard of recently hit about 18 miles from me and that super cell passed right through here just before it formed a funnel. i was a bit further toward the northern portion of the super cell and not where the funnel formed on the southern portion of the super cell. 1" hail here and others saw golf ball sized closer to where the funnel was. i haven't checked my pvs yet as it turned colder and i've been ill.

[boB]

WoW, Niel !   I hope everything turns out OK with them falling golf balls !!

Yeah, I think those LA302s might have a better chance if the arrestor is put on the tower (wind or solar) and
the wire run is a long ways away from the rest of the equipment.   May not help the stuff on the tower
though as that stuff may break at voltages lower than 7 kV.

boB

[mark]

Thanks for all of the responses. 
Would the new midnite lightning arrestors be considered a surge protector as well?
If not, what surge protector is recommended to protect an Outback FX80 and a Magnum 4448.

[Halfcrazy]

The MidNite product is a surge protection device. It meets the new UL standards and comes in 3 flavors. Here is a link to the product. http://www.midnitesolar.com/pdfs/SPD_Installation_manual_3%20_2_.pdf

[niel]

WoW, Niel !   I hope everything turns out OK with them falling golf balls !!


boB

boB,
one has to look on the bright side sometimes as it could've been worse. it could've been hailing golfers.

four!!!!!!!!!!