Electrical Panel & Solar - Center Fed and 100A?

[inetdog]

Yes, residential electric is 240 V single phase. In the US, because the 240 v is delivered by two hot conductors each 120 V to ground, but 180 deg apart in phase, it is sometimes called split phase power. In Europe, there is really a single conductor that runs 220 V-240 V to ground.

And in all cases the micro output is single phase involving two wires, only the trunk cable and the voltage programming differ.

[sensij]

Yes, residential electric is 240 V single phase. In the US, because the 240 v is delivered by two hot conductors each 120 V to ground, but 180 deg apart in phase, it is sometimes called split phase power. In Europe, there is really a single conductor that runs 220 V-240 V to ground.

[Dan Z]

That makes more sense and matches the photos I saw. But, on the SDG&E net metering application they only list 1 phase and 3 phase as options. Not sure what to make of that. I'm checking 1 phase to match the 240 V.

[sensij]

3G2.5 is the part number for European installations. Their electrical standard is hot, neutral, ground. In the US, you have two hot phases 180 deg apart. Look closely at the US datasheet, you'll see red, black, white, and green.

[inetdog]

From Enphase: "The voltage types are either single-phase or three-phase. All Engage Cable connectors bear labels indicating the voltage designation. Single-phase (3G2.5) Engage Cable includes three conductors. Three-phase (5G2.5) Engage Cable includes five conductors. Because Enphase microinverters output onto one phase, the 5G2.5 Engage Cable balances the phases by rotating conductor use from one microinverter to the next as shown in the following diagram. "

3G2.5 cable (ET10-240) is for 240 V (residential) So, the 240 V microinverters are one phase after all. Three conductors: line, neutral and earth ground.

It seems reasonable that the three phase 208Y/120 connection also has each inverter supplying power from line to line (at 208 instead of 240) with the neutral not playing any role in power transfer.

[Dan Z]

From Enphase: "The voltage types are either single-phase or three-phase. All Engage Cable connectors bear labels indicating the voltage designation. Single-phase (3G2.5) Engage Cable includes three conductors. Three-phase (5G2.5) Engage Cable includes five conductors. Because Enphase microinverters output onto one phase, the 5G2.5 Engage Cable balances the phases by rotating conductor use from one microinverter to the next as shown in the following diagram. "

3G2.5 cable (ET10-240) is for 240 V (residential) So, the 240 V microinverters are one phase after all. Three conductors: line, neutral and earth ground.

[Dan Z]

Yup, 10/3: two phases for the 240 V and one neutral. Plus earth ground. I forgot they output 240 V.

I believe data for the envoy is sent by the microinverters and embedded in the 60 Hz signal. The envoy gets the data through it's own 120 V power cord.

[sensij]

I think enphase inverters require the neutral, so 10/3 would be needed. At least the engage cable has a neutral in it. Not sure what it is used for - voltage monitoring maybe?

Yeah, thanks. I whiffed on that. I think the neutral is required for UL compliance, if nothing else. Enphase uses it for the powerline communication too.

[philips]

..10/2 + ground cable..

I think enphase inverters require the neutral, so 10/3 would be needed. At least the engage cable has a neutral in it. Not sure what it is used for - voltage monitoring maybe?

[Dan Z]

Got it. Thanks!

[sensij]

OK. I follow that. The Soladeck looks like a very convenient box! One question on it: If I am putting a 25 A two pole fuse in the main breaker box, why to I need additional branch fuses in series in the solardeck? This seems redundant, and if they ever trip, someone has to go on the roof to re-set them. I would have assumed that just a terminal block to join the conductors would go in the Solardeck. Good to know I can skip the FMC. I'll do a some research on the rules for the Romex routing.

Thanks for all the great advice! I'm sure I will have some more question, but I think I am about 90% done with respect to knowing what to do.

The Enphase truck cable is 12 AWG, which must be protected by OCPD with a rating no more than 20 A. The problem is the *minimum* required OCPD rating for the combined circuit rated to produce 20 A continuous is 1.25x, or 25 A, too high to protect the trunk cable. So, to protect the trunk cable, additional OCPD is required for each string before they are combined. If Enphase sold 10 AWG trunk cable, it would be good up to 30 A (typically), and individual branch OCPD would not be necessary.

[Dan Z]

OK. I follow that. The Soladeck looks like a very convenient box! One question on it: If I am putting a 25 A two pole fuse in the main breaker box, why to I need additional branch fuses in series in the solardeck? This seems redundant, and if they ever trip, someone has to go on the roof to re-set them. I would have assumed that just a terminal block to join the conductors would go in the Solardeck. Good to know I can skip the FMC. I'll do a some research on the rules for the Romex routing.

Thanks for all the great advice! I'm sure I will have some more questions, but I think I am about 90% done with respect to knowing what to do.

[sensij]

Yeah, you aren't going to fit two PV breakers and an A/C circuit in that panel. I've mentioned that you could combine the two PV strings externally and run them into a single 25 A breaker (two pole). That would leave room for the A/C circuit. A relatively painless way to do it is to use a Soladeck junction box to make the pass-through from the roof to the attic. Model 0760-41 is 6" deep, apparently designed for tile. You can put the breakers inside it (there is a kit, if you look) and combine the trunk cable to a single 10/2 + ground cable for the run to the service panel. Since you need to have a pass though of some kind anyway, it isn't really adding much in the way of components, just some cost. (probably $200 or so). If you DIY a panel upgrade, the cost might be comparable, but that is a lot more work. Paying for an electrician to do a panel upgrade could approach $2k.

And, just to revisit what was written earlier... although your plan with FMC is OK, conduit is not usually required in an attic. You can transition to Romex in the Soladeck and run it like any other AC circuit through the attic and house

[FFE]

That picture and info will get you the answer you need.

[Dan Z]

Below are some photos of my box. There are 6 tied 15A and one 20A. My gut is telling me that I will need the RMA or something like you suggest to add the 4 ton AC. Hopefully not a new box.
Any suggestion on how to reach the AHJ?
Not sure what I have in the way of ground rod. I will check when I get home.

Panel closed.jpg Panel.jpg