Solar hazard

[Boywinston]

I am reading that solar panels must be grounded. Is this true, and how do you ground them?

 

[FilterGuy]

There are a couple of things hidden in the question.

Solar panel frames
The NEC requires the metallic frames of solar panels to be grounded. The frames should have a solid connection to a wire going down to the buildings grounding system. Most panel racking systems will have a recommended way to tie to the grounding wire. Sorry.... I do not know off hand what the requirements for the gauge of wire is.... but I imagine it has to be at least as large as the power wires coming off the pannels. (Note: The grounding conductor must be a different conductor than the power conductors.

Circuit Grounding.
Any DC circuit that operates above 50V is required to have either the positive or negative leg of the circuit tied to the building grounding system. (This includes 48 volt battery systems because they charge at well over 50V).

Below 50V, tying one leg of the DC circuit to the grounding system is optional but highly recommended.

Note: When bonding things to the buildings grounding system, always ensure that there is only one path to ground.

 

[sed6]

Question, how do I physically make this connection?

 

[Viron]

Question, how do I physically make this connection?

Google WEEB. I believe that will take you to approved grounding connectors for PV panels. WEEB are stainless steel connectors that have tiny spikes that puncture the surface of the PV frame and allow you to attach a ground wire.

There may be a special paste to put down before using the WEEB.

The spikes are protected from air after puncturing the surface of the aluminum frame.

Aluminum very quickly developes a thin oxide at its surface that prevents further corrosion of the aluminum. However, the aluminum oxide has relatively high resistance.

For lighting protection you want EXTREMELY LOW RESISTANCE.

I believe most building codes only require 8AWG or 10AWG ground wire. If you are in a lightning prone area I wouldn't use anything smaller than 2AWG. Commercial installations use #00 and #000 stranded copper wire.

The big wires would be on the PV array and PV equipment with multiple 8ft ground rods no more than 8ft apart around the PV array.

For the ground tie to the commercial power 8AWG or 10AWG would probably be fine. You want an easy direct path to earthground.

Lightning arrestors are additionally installed for further protection.

If your PV system is only a few hundred Watts proper lightning protection will cost more than your whole PV system, so at some point there has to be a cost-benefit analysis between meeting code and real lightning protection.

There is a lot to lightning protection. Its a huge topic beyond the scope of this forum.

 

[kernel]

Question, how do I physically make this connection?

There are any number of ways. A purpose built rail lug on mounting equipment with integrated ground bonding is simple.

You can use lay in lugs, direct burial or outdoor "pool lugs" and star washers with through bolts.

There are neat stainless ground connectors like what is on a microinverter which could work.
I have stud/split bolt type.

They would go on the hole in the module frames marked with the ground symbol.
Weebs work well. (No paste).

Sometimes a weeb-lug.

 

[Capt Bill]

Re: posted Note: When bonding things to the buildings grounding system, always ensure that there is only one path to ground.

Appreciating this thread after learning of my option to ground my 24v LiFePO4 battery. I now have my LiFePO4 battery bank connected to 3 LV2424 All In Ones configured to 240ac split phase output, with AC Grid In to All In Ones; & all grounded to my 50amp house sub panel; which is wired via 6AWG/3 stranded copper Romex with a 10 AWG solid copper ground wire to my Main 100 Amp Grid IN Panel which is about 70 feet away from my 50Amp sub panel. . I am in Northern California where lightening danger is rare.

I have wired up three houses on my own, and must confess I do not fully understand everything I could about proper grounding. In Costa Rica, in a huge lightening prone area, I worked with a knowledgeable buddy and put in multiple ground rods at my 100 amp Grid Input breaker box; and at my Shipping container house near it's inside breaker panel, then also grounded my shipping container shop's 60 amp sub panel at other end of property about 150 feet away from original ground (three ground areas all coonected to same ground wire path; from metal shipping container (one with hollow metal tubing frame for walls and roof upstairs). I have seen that grounding system work. Sometimes Lightening is so close, it sounds like cannons going off, and at least one lightening hit fried many peoples connected equipment when the surge traveled widely through the neighborhood's telephone and grid wiring.

I recently learned a California buddy with a nice $25K off grid solar system has his bigger than mine battery grounded (learning more all the time). Reading here that grounding my 24vdc battery bank is optional might be why the LV2424 manual does not mention that (but same manual covers a 48v system). I see the recommendation by at least one knowledgeable forum member to ground my 24v battery. I do plan on grounding my DIY metal tubing racks for my upcoming 4000 watts of PV to house ground. My current 400 watts of Solar Panel has never been grounded, and that has not presented any problems over last couple of decades.

Question: What are pros and cons of adding additional grounding rods? ... and which locations might be best ??? ... I have in the past considering adding a ground rod near my 50mp powered sub panel ( that is grounded via a 10 Awg solid copper ground wire/ with a 6AWG neutral wire going to same ground bus bar); that 70 feet away from main 100 amp In grid panel plus orriginal and only ground into earth. I have also considered grounding at my outdoor above ground pool (extra water storage) that is connected to ground via 10 awg wire (including 10AWG ground wire) to my sub panel, that is about 225 feet away from my original (currently only) ground rods into earth. Is leaving the One Grounding Rod location at my Main Grid In Breaker Box really my best choice? or are there contrasting opinions?

... and what are the opinions about my 24v battery ground too?

I would appreciate hearing from those more knowlegdable than me about grounding: What's your Take on my best ground rod position(s) if I put in an additional ground rod or two in the ground ??? Thanks in advance or any further info. or opinions :+)