Southern California Utility Girds For 350,000 Electric Cars

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One of the long-standing concerns over electric cars is just how much demand the electricity grid would have to cope with should millions of people start plugging in every night.

California will be a good test-bed for such concerns, with as many as 350,000 electric cars expected on the state's roads by 2020.

That's according to Southern California Edison (SCE)'s white paper, "Charged Up" (pdf document), via KCET. The utility currently has around 12,000 electric car drivers using its services, so 2020's figure will mean a real surge in demand--the sort of surge some utilities are a little worried about.

The Charged Up white paper outlines SCE's efforts to prepare for such an eventuality--and it may not be as negative as some previous reports have made out.

Customer habits helping transition

While SCE notes that the average electric car draws the same sort of power as the whole of the rest of a house combined, widespread use of regular 120V "Level 1" charging is resulting in far lower impact than some studies have predicted.

Around a half of SCE's existing electric car-driving customers use Level 1 charging as opposed to higher-voltage Level 2 installed chargers. If that proportion continues, grid load won't be quite as high as expected and the transition towards greater numbers of electric cars will put less strain on the grid.

Electric car owners are also doing SCE a favor by making best use of "end charge time" functions. Rather than plugging in and using up juice when they return from work, many users with programmable charging options are setting their cars to finish by a certain time instead--30 minutes before work the next morning, for example.

This spreads load on the grid, as each electric car charges at a different time depending on the battery's charge level. Short commutes help with this--electric cars are rarely charged from completely empty.

Constant upgrades

Even so, changes have to be made--and SCE has identified parts of the grid that need updating to cope with higher voltage demand. Several hundred thousand power distribution poles will need replacing or upgrading and other parts of the service will need improving too.

To its credit, this is already happening--SCE says it already sizes its transformers for the proliferation of high-power plasma TVs which have appeared over the last decade or so. And most existing changes are simply routine improvements--less than one percent of recent improvements has been directly attributable to plug-in cars.

There are other concerns too, which still need to be considered. Many modern electric cars are coming with higher-capability on-board chargers, which increases demand.

Electric car adoption could happen quicker than the utility estimates too, as will any change in the status quo regarding multi-unit residents: those in condos and apartments potentially interested in electric vehicles, but holding off as their building or complex doesn't have suitable charging provisions.

The positive thing to take from all this though is that major utilities are thinking long and hard about the demands of electric vehicles--and ensuring that as EV adoption increases, so too will the grid's ability to handle all those extra people plugging in.


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Comments (25)
  1. Utility companies can control much of it with lower nightly rates.

  2. Hi Mark, not just that but it's easy to use the EV charging to stabilize the grid just by cycling the chargers to charge at demand peaks and cut off with demand surges on a minute by minute basis.

    This means the EV's are charged with what would be wasted power between demand and production.

    Another is many homes especially with EV's have solar too so they already produce their own power.

    Presently just 1kw of PV would charge most EV's for 25 yrs that the PV panels are costing just $800 retail now, sunelec.

    Facts are utilities have always said they have plenty of capacity for EV's. I don't think I've ever heard one say otherwise as they look at them as a juicy market instead of a problem.

  3. You know, I totally do not get this. My car does not pull any more power than my air conditioner and my car has the good manners to draw its power at midnite during off-peak. If utilities can supply power for every air conditioner in my neighborhood running flat out during the hottest part of the day, why can't they supply electric cars in the middle of the night? Saying that the electric car draws as much as the rest of the house combined is just BS. I fully charge my 60 kWh battery every night through a 30 amp breaker - what's the problem?

  4. A/C loads are non-continuous, as the compressor cycles, and also, they don't pull high continuous current.

    For now, if most EV owners make use of off-peak rates (not all will) it's less of a problem. The biggest issue is the local distribution system. If everyone on your block got an EV and charged off-peak, you'd definitely be blowing feeders and transformers, as they are almost always "oversubscribed". For example, it's not uncommon to see 4 houses with 200A service each sharing a 35kva transformer. If those 4 neighbors all get 10kW EV's (Teslas), that's over a 40kW load, thus overloading the transformer!

  5. Just think what would happen if most homes cook a 20lb stuffed turkey in an electric range… all for he same meal?! That's 3.5-4.0 hours of continuous power through a typical 220 volt, 30-amp circuit. Most family's cook their thanks-giving meal during the day, and not overnight when other home power use is lowest.

    For reference, an EV home charging takes ~8kWh of electricity to recharge ~30 miles of travel used during a typical day. (8 hours on 120V:15A, 4 hours on 120V:30A, 2.5 on 220V:15A, or 1.5 hous on 220V:30A circuit).

  6. Brian Once the over is preheated the heating elements cycle on and off. So the average power consumption is much lower than that 30 amps circuit might lead you to believe. And in the northern hemisphere not many folks are going to simultaneously use their air conditioner. :-) Nor do they cook turkeys five days a week all year round.

  7. My utility data feedback shows the duty cycle on my A/C running over 75% for hours at a time and we could get down in the weeds about distribution transformer ratings and running in the cool of the night, but no need. When I see three more of my neighbors get Teslas, I will start to worry - or not.

  8. Norm

    I agree there is lots of head room already in the current power distribution system IF people charge their EVs during off peak times. But as EVIng says, EV charging is a long duration continuous load.

    I have a sizable house and live in a hot area. The highest single hour for AC power draw this year has been 7.6 kwh. And this was only for a short duration on a single day. As you know a Tesla charger can use 10kwh or even 20 kwh per hour for many hours in a row, every commuting day.

    So while there IS some available head room, it seems clear that EV's will use up that margin, at least in some neighborhoods. So while the sky isn't falling as some would have us believe, this IS something the utilities need to be proactive about.

  9. I used to work for an electric utility and I assure you that if the (unlikely) need arises, they can upgrade distribution transformers a lot faster the car manufacturers can fill neighborhoods with electric cars. They are monopolies, have a guaranteed rate of return and make money on every kWh and every dollar they invest in hardware. Given their recent arguments for why solar power is just so unfair to their other customers, excuse me if I am a bit skeptical.

  10. do you really commute 250 miles a day? If not than you are not using "10kwh or even 20 kwh per hour for many hours in a row"... I have no idea about your commuting, but you need only 2 hours of 10kW for 60miles commute roundtrip.

  11. Odd, my Level 2, 50 amp. 240 volt charger draws roughly 3 times the power as my A/C. But then again, I charge at super-off peak, so it doesn't effect the grid.

  12. There are more comments in this thread
  13. I was very surprised that "Several hundred thousand power distribution poles will need replacing or upgrading"

    I couldn't find any reference to "poles" in the SCE Charged Up PDF. Did that figure come from another source?

  14. While SCE notes that the average electric car draws the same sort of power as the whole of the rest of a house combined
    maybe a house with no airconditioner. Plugging in a level 2 charger is no more than a mid-size airconditioner. Did anyone check how many houses and apartments start their AC at 5-7 PM? Far more than cars

  15. Yuval, that entirely depends on the size of the Level 2 charger. Tesla's Level 2 chargers go up to 20kw which is far larger than a "mid-size (residential) air conditioner"

  16. I have no sympathy for So Cal Edison or any of the California Electric companies considering they fought legislation that would have encouraged more residential solar systems. Many of us here were waiting for legislation that would mandate these companies to buy back surplus electricity at reasonable rates from residential customers who from their solar systems produce more electricity than they consume. These companies fought this so now they are only compelled to buy 10% above of what their customers consume. They don’t want tens of thousands of small producers because that would reduce their stranglehold. Shame on them!

  17. And lots of 80s homes in Northern California only comes with 100A services.

    They would all need to upgrade their breakers if they end up getting Telsa Model S with 20KW chargers...

  18. So, the utilities are worried that they won't be able to supply demand for that thing they sell for a profit? Yes, it's a real problem when too many people want your product. You need to tell them "No!", I don't want to make more money.

  19. Not if they have to sell the electricity at a discount while upgrading the transformer for "few" night time Telsa owners since they have a lot of solar panels on the roof...

  20. no mention of V2G. That should be a requirement.

  21. The major utilities are calculating the opportunity to go to their respective PUC's to request rate increases to support EV's. San Diego is already peaking to $.38Kwh and highway recharging centers are typically at $.50Kwh or higher.

    The last study I read was suggesting $14T to upgrade the U.S. grid to convert 50% of the ICE vehicles to EV's. Since CA drivers represent about 1/6th of the U.S. population, the upgrades in CA might cost as much as $2T in today's money (adjusted for historic timeline of installed substations, wiring, etc.). However, there are 145 nations now building smart grids and the Cu price has risen radically over the past 10yrs. In another 10yrs the price of Cu might force migration to Al. Continued...

  22. Yes - that's exactly what this is about. If you had to pay out-of-pocket today to upgrade your local transformer because your neighbors might someday all buy electric cars with 20 kW chargers, would you do it? But that's exactly what the utilities want to do for you. They get the benefit of a guaranteed return on the upgrade investment today and you get the benefit of paying for it. Can I sell you a shiny new nuke plant?

  23. Cu to Al?

    Most of the power lines and all the power lines to home are already AL stranded wires. Most of the service to home wires are also AL already...

    NO reason why a "properly" designed Al stranded wires can't be used instead of copper in EV infrastructure.

  24. Large scale migration to EV's is simply not economically viable and certainly not sustainable today.

    Better to Join the U.S. Migration (Google etcgreen migration)...

  25. @Steve: Sources and studies and data for this rather sweeping assertion, please?

    There are a number of well-regarded studies that differ from your conclusions, so let's debate this on the merits. Please provide online links to your evidence.

Commenting is closed for old articles.

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