Inverter PV Size?

[Hedges]

150A main breaker is for up to 120A continuous current (either loads or backfeed, but don't worry about sum of those two.)

200A main panel busbar x 120% = 240A
240A - 150A main breaker = 90A backfed breaker allowed.

(Or did you say a 225A busbar was put in it? Would be nice to have a sticker saying so if that's the case.)

 

[Cmy]

No, going with a 175a in the 200a main. Easier than a panel swap and gives me 65a of backfeed ability. Covers SA 15 62.5a out, EG4 18 50a, and an 11.4 48a. 1.25x48=60a breakers.

Be interesting to see how many amps that 200a uses and see how low that main could go. Doubt it is over 100a though the two minis are put on max heat the few nights drop to low teens.

Any way to measure one panel?

 

[Hedges]

52A continuous backfeed, not 65A.
You do show 1.25 x 48 = 60A breaker (60A x 0.8 = 48A continuous), but I don't know what your SA 62.5A & EG4 5A are about (other models under consideration?) 62.5A might cause nuisance trip.

200A busbar x 120% = 240A
240A - 175A main breaker = 65A backfed breaker
65A thermal breaker x 80% = 52A
52A x 240 = 12,480W

 

[Cmy]

Hoping the 175a main would still work if I ever decided to go hybrid and battery using a Sol Ark 15 or EG4 18kPV. No outages since the freeze making battery backup a low priority.

 

[Hedges]

You can put CT at 65A breaker connection, tell 18kPV or other inverter with the feature to limit export amps.

 

[Cmy]

Future proofing a second inverter feed to the lightest loaded 200a main, shifting amps from load to solar back feed.. Three mains split at the meter so grid tied nicely avoids which CT to measure. What makes future changes easier? Your 62.5a caution made me thinks some more.

 

[Hedges]

If you have lugs allowing 3x 200A panels and one is available, maybe 200A panel with 125A main and 100A backfed breaker. Or 225A, 125A, 125A.

Or just a 100A or 200A fused disconnect.

Or 200A panel, compliance not by 120% rule but by sum of PV and load breakers not exceeding 200A. e.g. 125A PV breaker and load breakers not exceeding 75A per leg.

 

[Cmy]

Didn't know about sum of breakers, thought 120% ruled. Thank you.

 

[Hedges]

1) Main breaker + backfed PV breaker at other end of bus doesn't exceed 120% of busbar.
2) Main breaker + backfed PV breaker anywhere on bus doesn't exceed 100% of busbar.
3) Backfed PV breaker and all load breakers do not exceed 100% of busbar (main breaker isn't relevant.)

The last one may be called "Sum of Breakers" rule, also sometimes "Hawaiian Tie-In":

https://www.nrel.gov/docs/fy23osti/85845.pdf

 

[Cmy]

Staying with the 120% rule. Counted breakers in the two room addition's 200a main panel and they total 585 amps. That includes the double 100a feeding the shop panel and a double 30a dryer breaker but no dryer.

 

[Ampster]

That includes the double 100a feeding the shop panel and a double 30a dryer breaker but no dryer.

Are you counting a double 100 Amp breaker as 200 Amps. If so that is not the correct math.

 

[Hedges]

Are you counting single-pole breakers?
Count breakers on L1. Separately count breakers on L2. Select the larger of the two numbers.

But obviously 585A worth of poles exceeds 200A/pole (for split phase).

You can use the sum of breakers rule as a way to convert an existing panel to pass-through, feeding downstream panels where you connect PV and relocated loads.

 

[Cmy]

No, counted total both sides. So a double 100a counts 100 for each side? Total of 11 doubles out of 16 breakers. Counting again, left side 285a, right side 340a.

Left dbl 50, dbl 20, 5 single 15s
Right dbl 30, dbl 20, 6 single 20s, dbl 100

 

[Ampster]

So a double 100a counts 100 for each side?

No a double is 240 volts and only counts as 100 Amps. That assumes it is not a shared neutral. When Hedges suggested to count both L1 and L2 but only use the larger number of that count, that may be an easier approach if you can open the cover and see which ones are L1 and L2.

 

[Cmy]

Probably why I should stay with 120% limit. With a double picking up 120v from L1 and L2 for 240v, it also picks up N amps form each side but ends up with N amps and not 2N So count one side only. Thanks for helping.