Skip to main content

How to efficiently charge your EV at home

I do most of my charging (90%) at home. Therefore, I thought a lot about how to most efficiently charge the car. My efficiency considerations are in three areas (there are probably more, but I focus on those for now):

  1. Use the lowest cost of energy $ per kWh throughout 24 hours: Dependent on your location and the utility company you are using, there might be different $ per kWh rates throughout the day or night. Also, some utilities offer special EV rates. Check with your utility to see what you can do to minimize charging cost.   
  2. Use the "cleanest" energy: Since we have solar and home battery, I try to use as much energy as possible from our solar panels to charge the car. In addition, you should avoid charging at high electricity demand times (in our area 3pm to 9pm)  because then the utilities use "peaker plants" to stabilize the grid, often using "dirtier" energy. Also, Tesla now offers an option in selected location to charge from solar only. Check out their website for more info.
  3. Minimize "waste" of energy: The waste of energy is probably minimal, but I still find it interesting to explore. I see two sources of potential "waste" when charging. First, the electronics in the car use energy to manage/process the charging session - let's say the car computer uses 150w per hour. Therefore, if you charge at a very low rate, maybe 1kwh, then 150w of the 1kwh are used just for running the system. If you charge at 6kwh, then the 150 w are a smaller percentage. Therefore charging on 120V seems to be more inefficient than 240V. Again, I have not calculated this in detail, but I think it is something to consider. Second, since we have solar, I try to use the solar energy produced to feed right into the car, versus storing it in the home battery and then charging the car later. Storing and converting solar energy in a home battery and then getting it back later can waste 10 to 20% through inefficiencies and AC/DC conversion (roundtrip efficiency). 
Tesla EVs offers a convenient way to schedule the charging session - you can set the time, the charging level and also the charging speed - all from the app. With that in mind, it should be fairly easy to charge your car as efficient and clean as possible based on your home set up (solar, battery) and the electric utility services in your area.





Comments

Post a Comment

Popular posts from this blog

My new Tesla Model Y

Early in August 2023, I finally decided to place an order for a Model Y - from the App. No dealership, no haggling, no waiting, I just configured it and placed an order on the iPhone.  A couple weeks later, I got the text - it's ready. I had decided to pick it up in Fremont - where the car is made. And I have to say this car is amazing. It's not only my first new car (my whole life I saved money by buying used cars, mostly Honda's) it is an amazing car. It's beautiful, it is quiet, it is luxurious, it is fast (really fast), it has amazing audio (love Spotify streaming!) and the interior is so sporty/comfortable/simple you just want to sit in there. But most important was that I can charge it almost everywhere (SuperCharger network) and that it has lots of cargo space for my work. Everyday, when I see it in my driveway I still cannot believe that this is my car now.  I have been waiting for this for almost 10 years (I will explain in a later post why I waited to buy a Te...
Post a Comment
Read more

Another Price Reduction for Model Y

Beginning of a new quarter and Tesla has reduced prices for Model 3 and Model Y (again). The Long Range Model Y is $2,000 cheaper and now costs $48,490 (before it was $50,490). Again, with a potential IRA federal tax credit of $7,500 this gets close to $40k for a medium sized luxury SUV. Tesla also introduced a new RWD (rear wheel drive) Model Y with 270 miles of range for $43,990. With the tax credit this moves towards $35k. Prices were also reduced for the Model 3.  Well, just like many others, I bought my Model Y at a higher price a while back. But I consider this as something that was expected. For one, Tesla tries to make the cars cheaper so that more people can afford an EV, and second, new technology (remember iPhone) is first more expensive with prices coming down over time. Well, Apple seems to go the other way now, since more phones cost close to $1,000, but that is a different story. So, since I have bought my Model Y for the long-term (10 years) I don't worry too much a...
Post a Comment
Read more