There are increasing rumblings across social media that the reason California’s power grid is on brink during recent week’s extreme heat is because the state has so many EVs. Others suggest that it’d be ludicrous to continue adding EVs because the grid obviously can’t handle it.

These arguments are just plain wrong, and are being lazily offered up by some of the same voices that claimed that EVs were not as capable as combustion engine cars in handling extreme traffic jams like last winter’s hour Virginia I-95 shutdown (not true), or that it could cost $900 to charge your EV during Texas’s 2021 winter storm/grid failure (false), or that the upfront environmental impact of producing an electric car vastly outweighs the long-time benefit of operating it (also untrue), and on and on.

Is EV charging pushing the California power grid to the brink?

No. It’s been really hot and for a few hours in the late afternoon and evening, the energy demand for cooling and cooking exceeds solar production. It doesn’t have anything particular to do with EV charging.

Let’s look at the data here to understand the reality. All charts are from California ISO for Wednesday, Sep 7, unless otherwise noted.

The California grid is being constrained for a few hours each afternoon (4-8 pm), when the grid operator is asking for customers to turn down A/C and avoid EV charging. Let’s see how that looked on Wednesday, September 7, 2022.

Why? 4:00 pm is when solar production drops off very quickly, because the sun starts to go down:

It’s still extremely hot out at 4:00 pm, so people need to use some A/C. And as they start to get home and cook dinner, there’s additional demand that can’t easily be shifted. But it’s incredibly easy to shift most vehicle charging to any of the other 20 hours of the day. 

What if every EV in California was plugged in at the same time?

There are 1,000,000 EVs on the road in California today. For the sake of extreme argument, let’s say that every single one of them was plugged into a Level 2 charger at home or at work at the same time in the middle of the day. This is literally impossible – there are nowhere near 1,000,000 Level 2 chargers in California (it’s more like 71,200). But let’s pretend!

On average, a single Level 2 charger draws 10 kW of power at a time. That multiplies out to a 10,000 MW demand at that same instant, which is substantially less solar production than the 13,000 MW that the state generates on hot and sunny days like Wednesday. So in the middle of the day, that’d be fine.

If 1,000,000 EVs were somehow suddenly plugged in the middle of the cooling demand spike, yes, that’d be a problem. It’d also be a pretty big problem if all 20,000,000 of the state’s combustion engine vehicles showed up at the same moment to fuel up at the state’s 8,000 gas stations. Both of these scenarios are beyond absurd.

How has power demand changed as EVs have increased?

Over the past 4 years, there’ve been more than 500,000 EVs added to the roads in California, more than doubling the number of EVs registered in the state. But peak demand on the grid with comparable weather? Only a 5% increase, and that’s including all energy usage.

Here are two demand curves from August 2018 and August 2022 on midweek days where the high in LA was identical.

Wednesday August 22, 2018

• High of 82 degrees in LA
• Peak demand - 39,000 MW
• Number of EVs on the road in CA: 450K 

Thursday August 11, 2022

• High of 82 degrees in LA
• Peak demand - 41,000 MW
• Number of EVs on the road in CA: 1,000,000

Solar production has increased by a lot more on a percentage basis since then. Over the same period (August 2018 to August 2022), peak solar production for California increased from 10,000 MW to 13,000 MW, an increase of 30%.

Where will this go from here? Physics Today recently published an analysis that at full penetration, EVs will only increase grid demand by 25%. In terms of raw wattage, there is enough electricity for a fully electric transportation sector. The issue is really the timing of when that electricity is used by other things.

EVs are part of the grid solution, not the problem

There’s three ways this is true:

1. Unlike air conditioning, EV charging load can be easily shifted. By charging in the middle of the day from solar or in the middle of the night from wind, you’re storing energy efficiently for use later. Depending on your vehicle’s charging controls and your charger itself, this can happen automatically, so you plug in when you get home and the car starts charging on its own when power is plentiful.
2. At the grid level, EV batteries that are plugged in and opted into various vehicle-to-grid (V2G) programs can participate in balancing the power grid directly. This is already happening with grid storage in California – notice the yellow “supply” line for Batteries that went almost 2000 MW negative from 7 am to 1 pm on Wednesday, soaking up extra solar production and then discharging it starting at 6 pm. The 1,000,000 EVs on the roads today (with millions more to come) could be storing much more excess solar production every day if charging and V2G infrastructure is built the right way.

3. At the individual level, EV owners essentially have their own backup generators in their garages when there are blackout events due to extreme weather. The largest battery in the new F-150 Lightning is 131 kWh, which is enough energy to run the average household in the US for 4 days. 

This won’t be the last time you’ll see misinformation on some aspect of EVs on Facebook that newsjacks current events. Cars are changing and it's happening faster than even the experts predicted. There are folks out there who are uncomfortable with this transition – which is fine, not everyone can convert from gasoline to electric right now anyway. It’s not surprising, but still it’s a shame to see the social media ecosystem amplifying misinformation from those people.