One of the first questions from a prospective electric car buyer is: “sure I’m not buying gas anymore, but how much will my electric bill go up?”  The answer, just about everywhere, is that an electric car is cheaper to drive, but sometimes it’s hard to figure out by how much.

It’s a complex question to answer because of different electric rates around the country, time-of-use rates, and fluctuating gas prices as well.  But last night, Tesla CEO Elon Musk suggested that Tesla could build software into their vehicles to answer just that question – and to help owners save money as well. The idea came, as many have, in a late-night answer to a tweet.

The twitter account for RPM Tesla, a Tesla aftermarket parts company, suggested that Tesla could add the ability to stop charging at a certain time, so the car wouldn’t keep charging through high-rate periods.  Currently, it’s possible to use Tesla’s in-car software to schedule a start time for charging, but it’s not possible to schedule an end time (though it is possible to set an end percentage, and with a little math, you can extrapolate this into an approximate end time).

This is common among electric cars, and most cars will have something like this (even my 2008 Roadster does).  The reason for this is utility time-of-use rates, which give discounts on electric rates for late-night charging.  These are popular with EV owners because EVs use a lot of energy but can be charged overnight when rates are lowest.  If you drive an EV and aren’t aware of these, you should definitely check with your utility to see if you could save money by charging at night.

Musk responded to this request by suggesting that Tesla could do even better:

 

The thing is, almost nobody has any clue what their electricity rates are, unless they already have an electric car or solar power system on their house.  Most people can give a sense of how much they pay on their electric bill, but not a rate per kWh.

While many EV owners have looked into their electric rates and know what the best time to charge is in order to get the best deals, there can still be a lot of complexities in understanding rates.  Utilities will offer several different rate plans, rates will be different based on season (with winter rates being higher at night and summer rates being higher during the day, due to heating and cooling), and rates can change based on how much electricity you’ve used during the month.

When considering all these concerns and fluctuations, utility rate tables can end up looking something like this, which can seem quite daunting to a newbie:

But even though it looks complex, it’s not too hard for an individual owner to at least understand the best time to plug in.  In this case, you’d typically want to start charging after 8pm and stop charging by 10am – but on weekends, you have low rates all day long.

And some utilities will give a much better graphical representation of when to plug in:

But that’s just the thing – every utility represents their rates a little bit differently.  To roll out a program like this, Tesla would need to collect data on every utility, in every location, and put them all into one program.  It would need to update this information regularly, it would need to know what plan an owner is on (including grandfathered plans, like the one I’m on), and it would need to do so while navigating different rate structures from utility to utility.

Similar ideas have been floated before.  At last year’s LA Auto Show, we talked with Nissan about a partnership with Fermata energy which would allow Leaf commercial fleet owners a way to profit off of the battery capacity of their cars by acting as distributed grid storage devices.  This is possible because Leafs have “vehicle-to-grid” capability, something which Teslas currently do not have, though they’ve thought about it before.

It’s a fascinating idea (so much so that we at Electrek turned down an interview with Margot Robbie in order to geek out with some engineers over peak shaving and demand charges), and could be both profitable and environmentally beneficial.  Smoothing out the electric grid during peak periods, when electricity is typically generated in dirtier ways, could clean up the grid a lot.  But that’s more focused on the commercial market than residential.

If Tesla wanted to build this idea into something even more complex, it could go further and partner with utilities to offer financial incentives for owners to charge at certain times.  One company, OhmConnect, already partners with California utilities in a system that gives customers a financial incentive to save energy during peak periods.  Perhaps Tesla could build in the ability to subscribe to a system like this and have a utility operator control when the car charges, using the car’s own internet connection to do so.

Electrek’s Take

While I love this idea and think it would be quite helpful for owners, it seems like a much more difficult task than an offhand tweet would suggest.  There are so many complexities to electric rates, as pointed out above, that it seems like it would take Tesla – which is already stretched thin at the moment – a lot of effort to implement this.

But it’s not impossible.  They could crowdsource rate information (with some sort of error checking), or ask utilities to input the information themselves, or only implement it for large utilities first. All of these approaches would allow owners and salespeople to just say “don’t worry about it, your car will figure it out for you.”  This is similar to Tesla’s approach on long-distance travel, where all you need to do is tell the car where you’re going and it will figure out when and where to charge and for how long.

Even though those of us at Electrek, and many of our readers, don’t have a problem with figuring out arcane electric rates, offering a simpler experience for customers is very powerful in terms of widespread adoption.  Especially for prospective buyers who may not yet know the difference between a kilowatt and a kilowatt-hour.

And while Musk’s idea won’t save money compared to an optimal charging strategy (unless an OhmConnect-like idea is implemented), it will make optimal charging that much easier, and offer owners more tools to save themselves money.  That’s always a good thing.

Update: since posting this article, we’ve received several comments from users pointing out local incentives in their area.  Norway has an app called “Tibber” which works similarly to OhmConnect, as does Denmark (theirs is called “True Energy”).  Xcel energy, an American utility which serves multiple states, has special off-peak EV rates at 3.3c/kWh (lower than their standard 12c/kWh).  It would take a long time to list everything here (just as it would take Tesla a lot of effort to program it all into their car).

The moral of the story is: check for special utility prices in your area!  There are likely incentives available to you as an EV driver and if you aren’t getting any, you might be missing out.


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