I personaly think we are talking about 2 differnt things For some price rules. I have been wiring for about 30 years. Here we have SqD, Westinghouse, Frank Adams, GE, Siemans and a couple of other names I dont use. I bought a home with a new GE panel and removed it to install a SqDQO before we moved in. SQD if any thing may be a little touchy with tripping quick. Rather that than not at all. And my wife likes the red window identifying the triped breaker. At our local parts house we had a demo a few years back that had a receptical fed by several name brand breakers. The point was to stick a paper clip into the recep and check the reaction time of the breakers. The SqD triped immediatly. The GE, Westinghouse and others fed the current to the point the paper clip burnt in 2. I thought that was a fluke and returned with 3 breakers from my truck. All tested the same. I buy SqD. I have been involved in other instances where GE fed the short and did not trip. With the new SqDHOM series you get the same tripping characteristics with out the red window and price competative with the others

"I don't have a torque screwdriver and from what I understand, 95% of electricians don't use them either." Use a torque wrench (inch-pound) with an adapter to 1/4 inch hex bits (this is a pretty standard size for 'screwdriver tips'). As long as you do not do anything to increase the lever arm a torque wrench works just fine, and are easier to find. You can stack up all the sockets and adapters you need. Most of the torques for electrical connections are surprisingly high. You are trying to make a gas tight connection for long term reliability and resistance to corrosion. Using a torque wrench makes getting the required torque a little easier than a screwdriver.

The current codes require that you run a ground to the remote structure in addition to it having it's own grounding system. What green conductor are you talking about? Are you talking about the one feeding the sub panel? In this case not only CAN you, you MUST connect that to the grounding system on both ends. You can use listed accessory lugs, check the Schneider catalog.

Once again, I am no expert, but just moving the breaker with its corresponding wires attached to another position in the panel, in my opinion, won't accomplish much because all the slots in the panel are tied to the same bus bars. What I suggested was to leave all the breakers in place, but let's say the troublesome breaker feeds "2nd storey lights and receptacles" and another AFCI breaker in the panel feeds "hall and living room lights". You would leave the breakers in place, and disconnect the hot wires going to "2nd storey lights" and "hall and living room" from their respective breakers. Then take the wire feeding "2nd storey lights" and connect it to the breaker that before was feeding "hall and living room", and the wire that once fed "hall and living room" would go to the troublesome breaker. If the problem is still with the "second storey lights", which are now hooked up to where "hall and living room" was before, it's safe to assume the problem lies within the wiring of "2nd storey lights and receptacles". If the problem is now with the "hall and living room", then it's safe to assume that the circuit wiring is not at fault and you are getting nuisance tripping, probably from the solar system. The other test I was suggesting about was to leave the breaker attached, and turned on, and leave its neutral pigtail connected to the neutral bus, but remove the hot (usually black or red) from the breaker. This way, if the breaker trip with nothing connected to it, it has to be nuisance tripping. Because you mentioned several lights and outlets in 5 rooms, my suggestion for you not to lose power to a good portion of your house, was to add a regular breaker, less expensive than an AFCI breaker, and buy an AFCI receptacle (they look just like the GFCI receptacle in your kitchen or bathroom, with test/reset buttons, but they trip on arc faults instead of ground fauts) to feed the circuit. This way the whole circuit (except for the short run between the panel and the AFCI receptacle) is protected agains arc fauts, but I would imagine that the receptacle would be less subject to stray voltages or surges that might occur in the panel. As far as the low ohms thing, I would not thing too much about it, we are missing information to really use that to troubleshoot. Here's a brief explanation of ohms. Ohms is the unit of measure of electrical resistance, just like the pound is the unit of measure of weight and the ampere is the unit of measure of electrical current. Good electrical conductors, like copper wiring in a house, have a resistance very close to 0 ohms. Poor conductors, like plastic or rubber, have a very high resistance in the order of several megohms (millions of ohms). Depending how and where they were measuring, "low ohms" could mean different things. If they were measuring ALONG wires, they were checking for a loose connection that could cause arcing and tripping of the breaker. In that case, you want the resistance to be as close to 0 as possible. Measuring ACROSS two wires, which is what it sounds like they were doing if they "found low ohms when testing the red wire to ground up in our attic", on a branch circuit, will only measure the resistance of what is connected to the circuit, like the resistance of every light bulb, ceiling fan motor, perhaps a radio or laptop plugged into a bedroom receptacle. Devices are connected in parallel, therefore the resistance measured across the hot and neutral wires of the circuit will vary according to what is connected or plugged in. For instance, a regular incandescent 100-watt bulb will have a resistance of roughly 150 ohms, but a vacuum cleaner could have a resistance as low as 10 ohms. It is normal, and the only way possible, to measure resistance with the circuit powered off.