200 Amp Center-Fed Service Panel Options?

[etlipman]

71SoCal - what did you end up doing? I am going to put in some effort to permitting some projects with this product as well connectder.com
Probably impossible in SDG&E territory since they already offer their RMA product, I doubt I'll get any SDG&E connected jurisdiction to approve the ConnectDER for use. But it was developed with DOE money, so maybe the local gov will give it a shot.

[inetdog]

Electrician should still be able to do a line side tap without that device.

Should be, in terms of knowledge and skills, but POCO has control of the line side of the service disconnect and can refuse to permit line side taps even when they conform to the NEC.
A good number of cities and POCOs do not allow line side taps in general, and this POCO would have the power to require that their meter adapter be used.

[ButchDeal]

Electrician should still be able to do a line side tap without that device.

[71SoCal]

SDG&E Renewable Meter Adapter (RMA)

I called SDG&E the other day to ask more about the Renewable Meter Adapter device. Recall that it's a supply-side tap that allows for a PV input.

It turns out that they have yet to install a single one of these devices...period. It's a pilot program that was supposed to begin installing devices as of Feb 2015. The rep told me that they've got over 200 orders backlogged, and now they're hoping to begin installs in Aug 2015. The rep wanted me to know that there is no certainty with the Aug 2015 date. So that's a bummer. Not sure what to do now. I'm considering adding the device to my single line electrical sheet just to get my permit approved. I could then move forward, installing the system and just hope for the best. If the RMA program doesn't get off the ground, my fall-back plan would be to upgrade my service panel.

[71SoCal]

So I went down to the City of San Diego’s Development Services Department to ask about my center-fed service panel issue. The inspector told me that they will absolutely NOT approve a PV back-feed on a center-fed panel if the sum of the main and the back-feed breaker exceed the bus rating, which is 200 amps in my case.

He told me that my options are as follows:

1) Replace the service panel to a higher bus rating, or with an end-fed main. (Even with an end-fed main and the 120% rule, my PV breaker might exceed that number).

2) De-rate the main breaker sufficiently. This would need to be signed off by a PE. (I don’t like this option anyway since my two a/c’s, pool pumps and oven alone draw over 120 amps).

3) Use the SDG&E RMA supply-side tap.

So with that, I’m thinking that the RMA tap seems like my best option. It seems easy (SDG&E does the work), and from the city’s perspective, my service panel is original and therefore doesn’t require any consideration beyond approving the RMA device. It will cost $1,326, but after the 30% federal credit, it comes out to $928.

[inetdog]

Wish I knew how to get an exemption from the fire marshal on the setback from the ridge. I don't have enough roof space to eliminate my electrical bill completely.

I have seen reports of success on exemption from the ridge setback on one half of the roof when the attic is one contiguous space and there is good access to ventilate the attic from the other side of the ridge.

[jsquared22]

There are exceptions or appeals possible. See the Calfire regs. One poster here, (in Poway if my memory serves) actually followed the S.O.P. and claims to have received an exemption from the fire marshal/rep.

Wish I knew how to get an exemption from the fire marshal on the setback from the ridge. I don't have enough roof space to eliminate my electrical bill completely.

[inetdog]

Code doesn't address center-fed busses, just that the backfed breakers need to be at the end of the buss. So it falls to the judgement of the inspector. As long as you have some serious loads in between the Main and the solar breaker, you are complying with the intent of the code and should be ok.

The statement of the 120% rule in the NEC is specifically associated with the backfed breaker being at the opposite end of the bus from the main, not just at one end.
When the main is in the center rather than at one end, every AHJ I have heard of has stated that the 120% rule does not apply for that reason.

Unless the panelboard is rated not less than the sum of the ampere ratings of all overcurrent devices supplying it, a connection in a panelboard shall be positioned at the opposite (load) end from the input feeder location or main circuit location.

[solarfrank]

Yes, good call! There is a 36" "Calfire" setback from the edges, ridges, hips and valleys. It's a lot of good solar real estate that is untouchable.

"Calfire" setbacks are 36" from ridge and edge, 18" from center of Hips and center of valley.

[J.P.M.]

Yes, good call! There is a 36" "Calfire" setback from the edges, ridges, hips and valleys. It's a lot of good solar real estate that is untouchable.

There are exceptions or appeals possible. See the Calfire regs. One poster here, (in Poway if my memory serves) actually followed the S.O.P. and claims to have received an exemption from the fire marshal/rep.

[71SoCal]

On roof space, don't forget to account for the fire setbacks or get a variance. Just sayin'.

Yes, good call! There is a 36" "Calfire" setback from the edges, ridges, hips and valleys. It's a lot of good solar real estate that is untouchable.

[solarix]

Code doesn't address center-fed busses, just that the backfed breakers need to be at the end of the buss. So it falls to the judgement of the inspector. As long as you have some serious loads in between the Main and the solar breaker, you are complying with the intent of the code and should be ok.

[J.P.M.]

I agree that from a current-flow standpoint, it would be fine to put the heavy loads (2-40amp a/c's and a 100 amp subpanel for pool/patio) between the main and the backfeed. But will an inspector sign off on it based on that? Would the proposed breaker configuration be part of my permit application? If I could do this, it would save me $1,400 skipping the RMA device.

BTW-I'm still drawing up my system. My thought was to start another thread once I get this service panel issue figured out. But quickly here's where I'm at right now...

I can get 275 watt LG panels and Enphase M250's for a really good price (my buddy is a contractor), so that's what I was going to start with. Ideally 32 panels for 8.8kW, but my best roof plane seems to only allow for 28-29 panels, tightly. I could possibly step up to 305 watt panels. I just know that 275 seems to be the sweet spot for pricing. I'm still trying to figure it out.

On roof space, don't forget to account for the fire setbacks or get a variance. Just sayin'.

[71SoCal]

What size is your inverter? You can go up to a 7.7kW inverter (SMA or SolarEdge) on a 200A panel using a 40A breaker. As long as it is at the end of the buss with as many branch circuits in between the main and backfeed breaker as possible, it will meet code. There might be some inspectors that will hassle this but the code experts I've learned from say it is OK to use center-fed busses.

I agree that from a current-flow standpoint, it would be fine to put the heavy loads (2-40amp a/c's and a 100 amp subpanel for pool/patio) between the main and the backfeed. But will an inspector sign off on it based on that? Would the proposed breaker configuration be part of my permit application? If I could do this, it would save me $1,400 skipping the RMA device.

BTW-I'm still drawing up my system. My thought was to start another thread once I get this service panel issue figured out. But quickly here's where I'm at right now...

I can get 275 watt LG panels and Enphase M250's for a really good price (my buddy is a contractor), so that's what I was going to start with. Ideally 32 panels for 8.8kW, but my best roof plane seems to only allow for 28-29 panels, tightly. I could possibly step up to 305 watt panels. I just know that 275 seems to be the sweet spot for pricing. I'm still trying to figure it out.

[solarix]

What size is your inverter? You can go up to a 7.7kW inverter (SMA or SolarEdge) on a 200A panel using a 40A breaker. As long as it is at the end of the buss with as many branch circuits in between the main and backfeed breaker as possible, it will meet code. There might be some inspectors that will hassle this but the code experts I've learned from say it is OK to use center-fed busses.