Upgrade of California install: Rule 21, 125A service / Line taps, PG&E...

[hex4def6]

Hi y'all:
I'm doing an install on a house that already had solar -- in this case it was an old sunny boy 6000 inverter connected to some (recalled) BP panels, for a total 5.7kW array. Well, I'm getting some money back for the recalled panels, and I thought I'd figure out what my next steps were.

I've already purchased a pallet of Canadian Solar 315W panels, but now I'm trying to figure out what the best ROI system set up would look like.

With NEM 3.0 right around the corner, I'd like to lock in the new size (9.45kW as soon as possible).
Some wrinkles: I'm on a 125A PG&E service / 100A house breaker. The way the solar was set up was using a line tap (bypassing the 100A breaker).

1. In my understanding, that means I'm allowed: 125A * 120% - 100A = 50A of solar, correct (12kW)? I know PG&E don't like doing line taps like this. Any ideas if they'll be ok with hooking more solar up to the same line tap? The wrinkle is I don't think the wiring they used for the tap is 50A rated.
(Alternately, I may end up going with one of their GMA collar thingies...)

2. The existing inverter is definitely not Rule 21 rated. Thoughts about just replacing the panels and keeping quiet for that section? I'd permit the additional (9.45kW - existing 5.7kW = +3.75kW) as a "new" install with RSD / new inverter... Since all the panels are off the roof, I'd just "replace" the existing panels after the fact...

3. I've been looking at potentially off-grid stuff. Are there any viable (cheaper) alternatives to the Sol-Ark stuff that's Rule 21 certified? Otherwise, I think I'm just going to go grid-tie and get a cheapie SMA 7.7KW.

4. Finally, I've been considering upgrading my service to 200A. Unfortunately, PG&E want like 8 months to draw up the plans, and who-knows how much money to actually do the install. Anyone have experience with that?

Thoughts?

 

[BentleyJ]

1. In my understanding, that means I'm allowed: 125A * 120% - 100A = 50A of solar, correct (12kW)? I know PG&E don't like doing line taps like this. Any ideas if they'll be ok with hooking more solar up to the same line tap? The wrinkle is I don't think the wiring they used for the tap is 50A rated.
(Alternately, I may end up going with one of their GMA collar thingies...)

While the utilities have to work within certain State mandates like rule 21, they have some flexibility in setting guidelines with regard to the line side tap question. It would be best if you obtained PG&E written rules regarding grid-tie interconnections.
The 120% rule applies to the bus bar rating when your grid-tie system is feeding directly into a main or subpanel through a breaker. 125A x 1.2 = 150 so you would be limited to a 25A breaker. However if the main breaker were downsized to 100A then I believe you could use a 50A breaker for the upgraded solar system. Load calculations would be needed to determine the minimum sized electrical service requirement and if the breaker could be reduced. Is your house all electric?

2. The existing inverter is definitely not Rule 21 rated. Thoughts about just replacing the panels and keeping quiet for that section? I'd permit the additional (9.45kW - existing 5.7kW = +3.75kW) as a "new" install with RSD / new inverter... Since all the panels are off the roof, I'd just "replace" the existing panels after the fact...

This is a building code issue subject to NEC and local jurisdiction. Its quite possible that the building dept. would require the old inverter to be upgraded as part of the new permit process. What is "grandfathered" and what is not can vary quite a bit, you need to get written guidelines from the building dept.

3. I've been looking at potentially off-grid stuff. Are there any viable (cheaper) alternatives to the Sol-Ark stuff that's Rule 21 certified? Otherwise, I think I'm just going to go grid-tie and get a cheapie SMA 7.7KW.

There is a 3rd option, Self consumption if allowed by local codes. In this case, you could use less expensive all-in-one type inverters that do not backfeed the grid. Depending on the number of inverters and battery capacity you could essentially cut your utility usage to zero but still have the grid connection to the AC input of the inverter(s) for times when there is not enough solar or battery to carry the load.
You mentioned Sol-Ark, take a look at Schneider XW Pro 6848. I'm using the previous model XW+ for whole house backup. Very reliable and output is substantially greater than the published ratings.

 

[hex4def6]

While the utilities have to work within certain State mandates like rule 21, they have some flexibility in setting guidelines with regard to the line side tap question. It would be best if you obtained PG&E written rules regarding grid-tie interconnections.
The 120% rule applies to the bus bar rating when your grid-tie system is feeding directly into a main or subpanel through a breaker. 125A x 1.2 = 150 so you would be limited to a 25A breaker. However if the main breaker were downsized to 100A then I believe you could use a 50A breaker for the upgraded solar system. Load calculations would be needed to determine the minimum sized electrical service requirement and if the breaker could be reduced. Is your house all electric?

This is a building code issue subject to NEC and local jurisdiction. Its quite possible that the building dept. would require the old inverter to be upgraded as part of the new permit process. What is "grandfathered" and what is not can vary quite a bit, you need to get written guidelines from the building dept.

There is a 3rd option, Self consumption if allowed by local codes. In this case, you could use less expensive all-in-one type inverters that do not backfeed the grid. Depending on the number of inverters and battery capacity you could essentially cut your utility usage to zero but still have the grid connection to the AC input of the inverter(s) for times when there is not enough solar or battery to carry the load.
You mentioned Sol-Ark, take a look at Schneider XW Pro 6848. I'm using the previous model XW+ for whole house backup. Very reliable and output is substantially greater than the published ratings.

Thanks for the response.

Sorry, forgot to mention, but house currently runs on a 100A breaker. House is currently not all-electric; heat is gas, as is hot water heater. I have been thinking about converting those to electric, but I think I'd definitely blow past my 100A/power budget doing that. That was part of the reason I was considering the 200A service upgrade, but 8months+ of waiting is not ideal....

Yeah -- I think you're right about the inverter. I'm pretty sure any reasonable read of the rules would consider that an alteration that requires a permit, and therefore would need to be brought up to the current code.

Self-consumption is an interesting thought. I'm not really familiar what that would look like schematically? Off-grid inverter w/ AC "generator" input?

 

[BentleyJ]

Thanks for the response.

Sorry, forgot to mention, but house currently runs on a 100A breaker. House is currently not all-electric; heat is gas, as is hot water heater. I have been thinking about converting those to electric, but I think I'd definitely blow past my 100A/power budget doing that.

Don't do it. Nat Gas is so much better even compared to so-called high efficiency heat pumps. Its hard to imagine Nat Gas price increases surpassing electric rates at least in the near future.

Self-consumption is an interesting thought. I'm not really familiar what that would look like schematically? Off-grid inverter w/ AC "generator" input?

Yes, an off-grid or hybrid inverter with export disabled such that you don't need a utility interconnect agreement. Schematically the options would be keeping the line side tap which feeds the AC Input to a hybrid/All-in-One inverter and then the inverter AC Output feeds to the main breaker. The inverter is programmed for Solar, Battery, Utility priority so utility power is only used when both other sources are not available and the transition is handled by the inverter software so you don't have to do anything.
Alternative 2. Install a new critical loads subpanel and move the important breakers to the subpanel. Main panel feeds the inverter, inverter feeds the subpanel. In an outage only the critical loads subpanel has power and only those loads can be operated from solar or battery while the main panel still uses grid power.
If you wish to include a generator then a transfer switch in front of the inverter would be necessary or you could use an inverter with 2 AC inputs, this is what I've done using the Schneider inverter. Would be happy to detail our set up in greater detail if asked but don't want this to get to long.

 

[fromport]

I'm on a 125A PG&E service / 100A house breaker.

Afaik you can have as much solar hooked up with a supply side connection as your main breaker (with a minimum of 60 Amps).
So I would say technically up to 100 Amp is allowed in your situation.

Question is if PG&E will let you hookup that much based on your usage and future expansion.
My guess that will be a *NO*

 

[Danke]

Thanks for the response.

Sorry, forgot to mention, but house currently runs on a 100A breaker. House is currently not all-electric; heat is gas, as is hot water heater. I have been thinking about converting those to electric, but I think I'd definitely blow past my 100A/power budget doing that. That was part of the reason I was considering the 200A service upgrade, but 8months+ of waiting is not ideal....

Yeah -- I think you're right about the inverter. I'm pretty sure any reasonable read of the rules would consider that an alteration that requires a permit, and therefore would need to be brought up to the current code.

Self-consumption is an interesting thought. I'm not really familiar what that would look like schematically? Off-grid inverter w/ AC "generator" input?

Are you sure the lines to your house are only 100A?

My duplex (built 1959) had two panels of 100A each. I figured the lines (3) coming in to house were 200A. Power company said I have 400A service.

 

[400bird]

I'm surprised by the 8 month wait time with PGE. Do you need a new drop to the house to support 200 amp service?

When I did my grid tie install with PGE, I also replaced the main panel. Upgraded from 100a to 200a and got rid of the fire hazard Zinsco.

I started the process with PGE in August. I wasn't ready to to the swap to the new service enterance and panel until October. The PGE rep started weekly calls to see if I was ready yet.
They also didn't charge for disconnecting the old service enterance and connecting to the new one.
Feels like my experience with PGE was far from normal. Going in I expected the 8 month wait your talking about and a huge charge from them.

 

[hayhayday]

Are you able to swap to a 200A panel and leave your 125A service? 125A is a lot , I have converted to all electric and run everything off a 100A sub panel, except my 60A emporia evse which only runs when I would otherwise be exporting, my peak 15 mins usage is only about 8kw(40A). I have heat pump water heater(30A breaker , ~3A running), two heat pumps(30A breaker, ~8-10A running), double electric oven(50A breaker ~15A running each), Induction stove (50A breaker ~1kw per burner on normal settings ~3-4kw on "boost" to boil water), heat pump dryer(30A breaker, ~4A running) etc

 

[hex4def6]

Are you sure the lines to your house are only 100A?

My duplex (built 1959) had two panels of 100A each. I figured the lines (3) coming in to house were 200A. Power company said I have 400A service.

Lines are 125A, breaker is 100A. I think they downsized the breaker to get the solar allowance.

I'm surprised by the 8 month wait time with PGE. Do you need a new drop to the house to support 200 amp service?

When I did my grid tie install with PGE, I also replaced the main panel. Upgraded from 100a to 200a and got rid of the fire hazard Zinsco.

I started the process with PGE in August. I wasn't ready to to the swap to the new service enterance and panel until October. The PGE rep started weekly calls to see if I was ready yet.
They also didn't charge for disconnecting the old service enterance and connecting to the new one.
Feels like my experience with PGE was far from normal. Going in I expected the 8 month wait your talking about and a huge charge from them.

Yeah -- current lines are 125A. The 8 months is what I've been told been told, not sure how accurate it is. Was your install underground or from a pole? They didn't charge for the for the service swap? Interesting. Right now I'm in the hole $1500 for just having a caseworker. I called a random trenching company who spitballed $10k to do the trenching. From my call, it sounds like PG&E want ~$1700 to do the drawings.

I'm curious -- would it be possible for you to DM me the technical drawing PG&E made for you? (redacted if needed). I'm interested to see what $1700 gets me.

 

[hex4def6]

Don't do it. Nat Gas is so much better even compared to so-called high efficiency heat pumps. Its hard to imagine Nat Gas price increases surpassing electric rates at least in the near future.

Yes, an off-grid or hybrid inverter with export disabled such that you don't need a utility interconnect agreement. Schematically the options would be keeping the line side tap which feeds the AC Input to a hybrid/All-in-One inverter and then the inverter AC Output feeds to the main breaker. The inverter is programmed for Solar, Battery, Utility priority so utility power is only used when both other sources are not available and the transition is handled by the inverter software so you don't have to do anything.
Alternative 2. Install a new critical loads subpanel and move the important breakers to the subpanel. Main panel feeds the inverter, inverter feeds the subpanel. In an outage only the critical loads subpanel has power and only those loads can be operated from solar or battery while the main panel still uses grid power.
If you wish to include a generator then a transfer switch in front of the inverter would be necessary or you could use an inverter with 2 AC inputs, this is what I've done using the Schneider inverter. Would be happy to detail our set up in greater detail if asked but don't want this to get to long.

Good to know. I'm spending like $200/month on gas heating the water and house right now, which is painful. Maybe spending some dollars on insulating the house is a better bet. Although I am looking at the HVAC + Water heater needing to be replaced in a couple of years anyway....

Right now I'm technically on an interconnect agreement still, for the original solar panels that currently are off the roof. My understanding is that you get to stay on NEM 2.0 for as long as you "substantially" keep the same amount of solar. Of course, going from 5.7kW to 9.45kW probably doesn't fit that bill, so I want to get in on NEM 2.0 before the cutoff date.


Am I understanding this correctly for Option 1? In this situation, nothing would go through the 100A breaker?


Or is it like this, in which case I'm not sure how the inverter prevents itself from backfeeding?


I'd love to see what your setup looks like.

 

[400bird]

My service is above ground and must have been rated for at least 200a as the actual wire from the pole was not replaced.
The PGE worker cut it from my old service enterance, walked it over to the new, and crimped it on.
Sounds like you are looking at significantly more work.

I see you mentioned a hybrid inverter, you could ti a straight panel replacement for you roughly 6kw grid tie and take the remaining 3kw and hook those up to a charge controller to charge a battery. Also, many hybrid inverters include settings to limit sell or grid current.

Here's a link to all the approved equipment, you'll need to click around a little to get to different equipment types.

Solar Equipment List - CA Energy Commission

solarequipment.energy.ca.gov

 

[BentleyJ]

I'm spending like $200/month on gas heating the water and house right now, which is painful. Maybe spending some dollars on insulating the house is a better bet.

Its always more cost effective to not use a kWh than to produce it and save it for later use. Yes insulation, windows, weather stripping. You would be surprised how much hot or cold air can come through even a small gap between doors and door jambs if not tight. A full energy audit of your house is really worth the effort. I went through our entire house and made a comprehensive to-do list. Took a couple of years to get everything completed but what started out as an average 80's tract house now has very low energy consumption by comparison.

Although I am looking at the HVAC + Water heater needing to be replaced in a couple of years anyway....

Consider going high efficiency as in 18 to 20 SEER variable speed AC and 95% furnace. Condensing tankless water heater. The other consideration for variable speed equipment is they don't have the typical in rush current problem that single phase induction motors have thus are much more compatible with using an inverter.

 

[BentleyJ]

Am I understanding this correctly for Option 1? In this situation, nothing would go through the 100A breaker?
View attachment 123782

If the 100A breaker is in the meter panel and not in the house load/breaker panel then a line side tap is not necessary as the power can be derived from the breaker which provides the over current protection. However the breaker needs to be down sized to coincide with the inverter specs and internal transfer switch limits.

I'd love to see what your setup looks like.

I our case the house had the typical CA 100A combo meter & load center in one panel. I have attached a single line of our system but needs some clarification.
I didn't replace the original outdoor 100A panel. All the internal components were stripped out and replaced with the components of a Reliance 100A/60A manual transfer switch which now acts like a maintenance bypass. The 2 breakers are interlocked so only one can be ON at a time. Of course both could be OFF at the same time.
The new 200A main breaker panel was installed inside the garage opposite the outdoor meter panel and a nipple connects them through the wall. The outdoor 100A breaker is OFF and the 60A breaker is ON. You should be able to trace the power flow through the inverter back to the main breaker panel via a backfed 60A 2 pole breaker.
If the inverter ever fails the outdoor 60A breaker is turned OFF and the 100A is turned ON which feeds directly to the main breaker. Likewise the 60A backfeed breaker in the main panel is turned OFF. The house has utility power and the inverter is completely isolated for service.