Mike Holt: Solar PV Grounding Electrode System.
This information is mostly correct, and somewhat outdated. I deal with grounding communication towers among other things -- we use dozens of ground rods at times, sometimes more. There's literally a book on the topic --- motorola R56. We get some nasty lightning. The most dangerous is a pop up storm where lightning precedes the rain. After 10 minutes of rain, the lightning is much less dangerous in that it goes for the trees often. When it's dry, man-made structures take an unusually large number of strikes. I've got quite a few pictures of lightning damage. Personally I can't use enough ground rods.
They're all bonded together. Even out buildings / detached buildings. They too have a ground rod and are bonded to the primary structure's ground rods. Code calls for subsequent rods to use 6ga copper or larger, I use at least 4 solid. Towers are different, it's a web of welded copper. I design mine more organically than grid-like (see lichtenberg).
Grounding for lightning strikes is a "best practice" type of thing. There's still a substantial amount not known. We do have best practices / mitigation techniques. A lightning strike isn't a static value though. There's "small" bolts and there are "massive" bolts. They're not all the same, nowhere close (there's also streamers that some mistake for lightning, nearby strikes can cause your structure to throw one out). The big boys shoot a burst of radiation into space called a sprite. Sometimes despite best practices, the monsters still cook a lot of shit. In tower shelters we use halo rings and EVERYTHING is bonded -- I mean everything -- AC systems, all metal. For radios that are at the top and run to a switch, I figure 8 excess amounts of shielded network cable to increase its run to mitigate the odds of lightning using the cable. Before doing loads of research on the topic and implementing my current methods, I had 2 strikes 6 weeks apart that blew up some stuff. Since, I haven't had a single lightning related failure despite numerous strikes.
There's 2 different camps --- one that believes in central "home runs" and the others like myself that put copper everywhere and bond everything in multiple places. Some like to say it creates a "grounding loop" -- When you've got 4ga and larger copper running everywhere and connect to it at multiple places, it only creates a loop on paper. There's far too little resistance to get any loop effect going on. Panels on a roof are a no-brainer to bond and interconnect to the structure's grounding system. Lightning isn't water, it doesn't only take the shortest path to ground, it takes all paths to ground. One of the aforementioned strikes bit me through my mouse. Given the distance it traveled out of the all-plastic mouse from the mouse's ground plain (came out between the LMB and the housing), it was somewhere between 20 and 25kv. It jumped about an inch. Computer and everything connected to it was fine. My ADSB receiver didn't survive and its antenna was vaporized. That was the moment I went all out on mitigating the issue. I also use shielded network cable exclusively, including in-wall.