Questions regarding planning a new system.

[odie451]

I am new to solar, and am trying to learn as much as possible. I like the Enphase IQ8 series of micro-inverters, though the only reason I see someone using them is for solar-backup only. I am located in So Cal, so I am must likely regulated to a grid-tie with battery backup. I only have a 100A main breaker in my panel. I don't know if the bus-bar is 125 or 100, I will assume it is 100. My understanding is I am allowed a 20A breaker for a PV array, which would = 3840 watts.

My questions are:

In thread "Off grid for my house" post #22 @Hedges has the following

My Square D QO panels have 225A busbar and 200A main breaker.
225 x 1.25 = 270A
270A - 200A = 70A backfed PV breaker allowed
70A x 80% = 56A continuous current
56A x 240V = 13,440W

Where does the 1.25 come from. Is it based on fuse size?

Would the max array size I am allowed be = to 4800 watts vs the 3840 watts.
100 x 1.25 = 125A
125A -100A = 25A
25A x 80% = 20A
20A x 240 = 4800W

I currently use about 6600kwh/year. I would like to future proof a system that allows expand-ability, is this possible.

Is it possible to have 2 strings of panels each going into the IQ combiner and 1 input for battery backup.
1 string would be mounted W or E 90° of each other. Just like @Hedges mentioned in post#16 of the mentioned thread above.

If I go with the Enphase IQ7+ or IQ7a, can I use a battery besides the Enphase battery. Is it possible to use the Signature Solar EG4 batteries.

I am trying to figure this out before I lose the opportunity for NEM 2.0

Sorry if my post is all over the place
TIA

 

[Bri from IA]

Perhaps you should reach out to the person who wrote the post. I'm not able to follow the logic of his calculations.

That said, 1.25 and 80% (i.e. 0.8) are recipricals of each other. That amount is commonly used in sizing fuses and circuit breakers. For example, if an appliance requires 10amp for operating current, the breaker/fuse should be sized 12.5A minimum so I won't trip/blow while the divice is running.

You might consider going over options with a licensed electrician, even if you have to pay them for advice. You'll be able to move more quickly and cover more topics in a quick manner.