SDG&E Wants To Nearly Quadruple Its Minimum Charge To Customers

[Ampster]

As solar generation increases they have to swap out their current SCADA systems to systems that can handle bidirectional current flow.

I dont mind paying for information technology for them to send me price signals. My understanding of the impact of rooftop solar is it reduces load at the local substation. In reality my solar generation just goes to my neighbors who share the same transformer. I think bidirectional current travel is a wholesale problem created by distant solar farms.

As peak generation increases (solar peaks at noon) they will need higher current transmission lines.

As mentioned above rooftop solar will likely be fairly well distributed eliminating the need for more transmission. I recall some recent CPUC cases where they denied several IOU requests for more distribution or transmission. Maybe there is something I am missing in my simplistic view of the future?

As DER's with tight trip tolerances (i.e. non-Rule 21) proliferate they will need more frequency/voltage support to prevent cascading failures due to loss of generation.

I probably need to understand that issue better. I thought the point of Rule 21 was to give the grid more resilience? If adding megaWatt battery banks to substations or retired generating stations is what you mean by frequency/voltage support, I dont have a problem paying for that either.

[Mike90250]

That is a classic argument that the anti EV people use against EVs.
Actually it is when they get off the road and begin charging that the grid sees their load. Currently most EV TOU rates favor charging from 11pm to early am when there is plenty of capacity. In the future as solar proliferates we may see cheap rates at Noon to put load on the grid and soak up all that solar that is currently being curtailed. If the solar generation and EV charging are evenly distributed around the state there should not be any need for additional transmission and perhaps not much change in distribution lines.

I never really thought anyone, especially you, would really think I meant EV's would be dragging around a 12 mile power cord when being driven daytime. (I don't mean a literal 12 mile cord)
Generally, personal cars are not sitting in your solar carport in the day, they are in the parking lot at work, baking in the sun.
Meanwhile, at home, your GT-PV application was turned down, because the neighborhood is already saturated with PV (10%) and the local substation can't handle the backfeed and inverters are tripping off line from high voltage. So that's local infrastructure that needs upgrading. Or PowCo control over your inverter production and battery usage. I can't imagine how that could go wrong.

[ButchDeal]

Generally, personal cars are not sitting in your solar carport in the day, they are in the parking lot at work, baking in the sun.

Some work locations have Solar EV chargers to both shade and charge the EVs (shade for all cars though).

https://www.youtube.com/watch?v=ElmuPq3QCNU

[jflorey2]

I dont mind paying for information technology for them to send me price signals. My understanding of the impact of rooftop solar is it reduces load at the local substation. In reality my solar generation just goes to my neighbors who share the same transformer. I think bidirectional current travel is a wholesale problem created by distant solar farms.

In Hawaii they are having to restrict new grid-tie installations because some substations are getting very close to zero power during peak solar times, and they cannot handle bidirectional power flow. Currently on Oahu 25% of the distribution circuits are very close to 100% solar generation of the minimum daily load, and cannot handle any more solar without risking bidirectional flow (and other problems, like inability to protect against faults and overloads.)

As mentioned above rooftop solar will likely be fairly well distributed eliminating the need for more transmission.

See above. Solar is peaky; it generates power in the midday, which means if you want to offset close to 100% of your load, the system now has to handle peaks that are 4x your average load. At the local level that's usually OK because the system is designed for peaks, not averages. But as you move up in the transmission grid, from local circuits to substations to transmission lines, average behavior, not peak behavior, dominates - and at those levels you have to upgrade to carry all that solar power.

I probably need to understand that issue better. I thought the point of Rule 21 was to give the grid more resilience?

Rule 21 includes -

- parameters that let inverters ride through generation disturbances instead of tripping off line
- communications that allows utilities to monitor and curtail generation
- dynamic reactive power compensation helps keep the grid stable
- ramp rate controls so the inverter doesn't "slam" on when power returns
- new timings so inverters start coming back on line more quickly

[Ampster]

I never really thought anyone, especially you, would really think I meant EV's would be dragging around a 12 mile power cord when being driven daytime. (I don't mean a literal 12 mile cord)

It was my poor attempt at humor to make light of a theoretical argument that I often hear. In reality there is plenty of capacity. There may be timing problems but most people who have EVs have a lot of flexibility about when they charge. More and more will charge partially at work to take advantage of the abundance of solar energy at Noon as several have pointed out in this thread.

Meanwhile, at home, your GT-PV application was turned down, because the neighborhood is already saturated with PV (10%) and the local substation can't handle the backfeed and inverters are tripping off line from high voltage. So that's local infrastructure that needs upgrading. Or PowCo control over your inverter production and battery usage. I can't imagine how that could go wrong.

With a law coming on the books in 2020 that every new home built has to be zero energy and a state policy about aggressive Renewable Portfolio Standards, how are the utilities going to turn down those applications? Yes, they will try to make them less economical. If the utilities go too far as has happened in Hawaii, battery storage will become the complement to solar to make that combination more economical. What we may see is further income disparity as those that can afford it will make those investments and those that can't will be facing higher costs of energy.

Until we get close to 50% saturation most of the rooftop solar will just reduce loads at the substations. We are a long way from that happening. Rule 21 already gives the utilities control over inverter production. Yes there will probably be a few glitches but it is certainly not a 'sky is falling scenerio".

[jflorey2]

That is a classic argument that the anti EV people use against EVs.
Actually it is when they get off the road and begin charging that the grid sees their load. Currently most EV TOU rates favor charging from 11pm to early am when there is plenty of capacity. In the future as solar proliferates we may see cheap rates at Noon to put load on the grid and soak up all that solar that is currently being curtailed. If the solar generation and EV charging are evenly distributed around the state there should not be any need for additional transmission and perhaps not much change in distribution lines.

That's only true if everyone charges around midnight. In real markets (like the Netherlands, where this was studied) people tend to charge in two peaks - one around 3-4am (these are cars on timers) and one around 2pm (these are cars being charged at work, while shopping, or at home getting ready for a trip.) The peaks are about equal. In addition, all the 'on-road' charging takes place during the day - and often these are the 100+KW fast chargers.

So there will be a significant amount of work to be done to support all this. Some of it can be mitigated by putting solar at charging stations - but not all.

[Ampster]

That's only true if everyone charges around midnight. In real markets (like the Netherlands, where this was studied) people tend to charge in two peaks - one around 3-4am (these are cars on timers) and one around 2pm (these are cars being charged at work, while shopping, or at home getting ready for a trip.) The peaks are about equal. In addition, all the 'on-road' charging takes place during the day - and often these are the 100+KW fast chargers.

So there will be a significant amount of work to be done to support all this. Some of it can be mitigated by putting solar at charging stations - but not all.

I wonder if this has had much influence on the duck curve in California? I know they are curtailing more commercial solar now than before. My earlier response to Mike was that we have the capacity. I agree it is a timing issue and that there is also a lot of work to do.

[Ampster]

In Hawaii they are having to restrict new grid-tie installations because some substations are getting very close to zero power during peak solar times, and they cannot handle bidirectional power flow. Currently on Oahu 25% of the distribution circuits are very close to 100% solar generation of the minimum daily load, and cannot handle any more solar without risking bidirectional flow (and other problems, like inability to protect against faults and overloads.)

Hopefully their HECO rules give them some way to curtail the solar until they can get their grid fixed. I have not heard that is yet a problem in California but I can see how it could predict the future if something isn't done.. I did hear from a consultant a couple of years ago that a microgrid installation in the Central Valley had allowed PG&E to postpone some grid upgrades. I also saw a couple of CPUC rulings that denied distribution or transmission upgrades because they weren't necessary. I don't recall the details but maybe I had assumed distributed generation had reduced the need. It is a complicated subject and I would like to learn more so I can advocate for the correct solutions.

I had heard that substations could not handle bidirectional flow but never understood the physics. Am I correct in assuming that the transformer on my street can send my generation up to at least the next load on a nearby tranformer or two?

Rule 21 includes -

- parameters that let inverters ride through generation disturbances instead of tripping off line
- communications that allows utilities to monitor and curtail generation
- dynamic reactive power compensation helps keep the grid stable
- ramp rate controls so the inverter doesn't "slam" on when power returns
- new timings so inverters start coming back on line more quickly

I understand Rule 21 but I didn't understand why the DER resources that you mentioned can't be controlled with some mechanism. My understanding is CAISO can curtail commercial solar with some electronic communication and some studies have shown it can be shut down pretty quickly. I also understand that they can curtail rooftop solar with frequency shifts but I don't know if they have had to resort to that yet.

[bcroe]

I also understand that they can curtail rooftop solar with frequency shifts but
I don't know if they have had to resort to that yet.

I think there are terrible problems with frequency shifts, regardless of solar. Bruce Roe

[Ampster]

I think there are terrible problems with frequency shifts, regardless of solar. Bruce Roe

I honestly don't know on a macro level. When it happens on the grid I think it is symptomatic of load or generation imbalances. In California frequency/voltage consistency is one of the responsibilities of the Independent System Operator. I know it was a problem when most clocks ran off the 60 Hz signal. I sometimes see my inverter report grid differences of less than 0.1 Hz, but that might be a meter inaccuracy.

On a micro level it happens in AC coupled systems as a means to modulate grid tied inverters when the grid is down. In those cases the shifts can be several Hz. Reportedly they can trip some UPSs into backup mode.

[jflorey2]

Hopefully their HECO rules give them some way to curtail the solar until they can get their grid fixed. I have not heard that is yet a problem in California but I can see how it could predict the future if something isn't done.. I did hear from a consultant a couple of years ago that a microgrid installation in the Central Valley had allowed PG&E to postpone some grid upgrades.

Of course. Local storage on a microgrid allows peak shaving and load shifting, thus reducing load on the grid - but it is very, very expensive. Who pays for that? If it's the utility - that's where the new costs come from.

I also saw a couple of CPUC rulings that denied distribution or transmission upgrades because they weren't necessary.

Well, the CPUC and the utility regularly go round and round on this. Is that old substation that is at 95% capacity at risk? Does it have to be upgraded? Will the load grow? How fast? The utility thinks it will be at 100% within three years. The CPUC thinks that it's five years, and that's after the current commissioner retires, and let the next guy deal with it. Besides, they have been getting a LOT of sh!t over rate increases over the last two years, and the last thing they need is another one . . ..

I had heard that substations could not handle bidirectional flow but never understood the physics. Am I correct in assuming that the transformer on my street can send my generation up to at least the next load on a nearby tranformer or two?

Any transformer can handle bidirectional current flow. But monitoring, compensation and protection devices often assume one way flow, and either don't work or work poorly in the other direction.

I understand Rule 21 but I didn't understand why the DER resources that you mentioned can't be controlled with some mechanism. My understanding is CAISO can curtail commercial solar with some electronic communication and some studies have shown it can be shut down pretty quickly. I also understand that they can curtail rooftop solar with frequency shifts but I don't know if they have had to resort to that yet.

No, there's a separate communications channel they use. Frequency shifts are really hard to manage. There's a huge battle over curtailment, because if you spend $30K on your 10kW system, are you going to want the utility shutting it down twice a week for an hour, and losing all that generation during peak generation times?

[J.P.M.]

Of course. Local storage on a microgrid allows peak shaving and load shifting, thus reducing load on the grid - but it is very, very expensive. Who pays for that? If it's the utility - that's where the new costs come from.

Well, the CPUC and the utility regularly go round and round on this. Is that old substation that is at 95% capacity at risk? Does it have to be upgraded? Will the load grow? How fast? The utility thinks it will be at 100% within three years. The CPUC thinks that it's five years, and that's after the current commissioner retires, and let the next guy deal with it. Besides, they have been getting a LOT of sh!t over rate increases over the last two years, and the last thing they need is another one . . ..

Any transformer can handle bidirectional current flow. But monitoring, compensation and protection devices often assume one way flow, and either don't work or work poorly in the other direction.

No, there's a separate communications channel they use. Frequency shifts are really hard to manage. There's a huge battle over curtailment, because if you spend $30K on your 10kW system, are you going to want the utility shutting it down twice a week for an hour, and losing all that generation during peak generation times?

Jeff:

Your sensible and apparently (to me anyway) informed responses bring to my mind the old adage: " Don't bother talking sense to fools; they'll only poke fun at your words."

[Ampster]

I appreciate the fact that Jeff is willing to take the time to inform the readers of this forum about these issues. California and Hawaii are facing these issues because of the high percentage of solar. If the rate increase proposed in San Diego becomes a reality with the other two Independently Owned Utilities my hope is that money goes into infrastructure to make the grid more resilient for the future.

[SunEagle]

I appreciate the fact that Jeff is willing to take the time to inform the readers of this forum about these issues. California and Hawaii are facing these issues because of the high percentage of solar. If the rate increase proposed in San Diego becomes a reality with the other two Independently Owned Utilities my hope is that money goes into infrastructure to make the grid more resilient for the future.

One can only hope the POCO's will spend the money on infrastructure improvements and not on investor raises.

[J.P.M.]

One can only hope the POCO's will spend the money on infrastructure improvements and not on investor raises.

About as likely as monkeys flying out of my butt.

I spend a lot of time walking around the rural areas around my house ~ 1-2 hrs. at a time, 3-4 days/week, maybe a 2-3 mile or so radius +/-. Been at it for 11+ years now. Anecdotally, after seeing what's (not) happening in N. S.D. county with respect to SDG & E equipment with respect to basic maint., much less improvements, seems to me what amounts to the phantom infrastructure improvements are more fodder to justify rate hikes than anything substantive.

But - that's just more business as usual. Putting my $$ where my mouth (--->>> keyboard tapping) is, I'm keeping my Sempra energy (SDG & E's parent) stock.

The recent fed. tax handout to corporations sure has helped me, but from where I sit it seems to have done not much for the country's infrastructure or its people that I've been able to see.