On a recent Internet of Things podcast, we took a voicemail from Jared on our podcast hotline. Jared’s home is equipped with solar panels and he recently purchased a Tesla EV. He’s looking for some smart device that will let him charge his EV directly when his home is producing more energy than it’s using.
I can relate to Jared’s question because I had 41 solar panels on my prior home. I’ve since moved to a home without solar panels but we did purchase a Tesla Model 3 about a year ago. We’re also considering a solar panel install where we now live.
Jared’s house uses Enphase solar products. I know the brand because that’s exactly what I had at my prior residence. And Enphase makes a great product. However, unlike many other solar energy companies, Enphase has taken a traditionally different approach. Instead of having a single inverter to change DC power from solar panels to AC power for home use, Enphase uses a micro-inverter on each solar panel. This helps overall energy production in the case of shade cover on some panels.
That doesn’t mean Jared is completely out of luck; it just means his options are more limited. If he had one single power inverter, for example, he could replace it for one that supports EV charging separately from the other circuits. Of course, that wouldn’t be cheap, even if it was an option for Jared. I have spoken to some industry folks and I’ve heard that Enphase is starting to offer systems with a centralized inverter, mainly because that’s needed for optional battery support.
There are some “smart” EV chargers that support load balancing and solar-only charging. And these should work with Jared’s existing solar power system.
Unfortunately, they too can be pricey. That’s because they’re not just a standard EV charger; they have smarts and connectivity to see the flow of electricity from the panels to the home to the grid. However, they can be far less expensive than upgrading your solar inverter. A reader reached out us after the podcast to point us to the Emporia Electric Vechicle Charger with additional home energy monitoring solution could suffice for $440 in total. Four hundred dollars of that cost is the charger, while the required energy monitoring hardware is just $40. That particular monitoring solution only works with a handful of energy providers, so an alternative energy monitoring option might be needed.
Clean Energy Explained, where the above image comes from, has a list of 10 smart EV chargers to consider. Some of these, however, are well over $2,000, making me wonder if it’s even worth it for Jared. Each has different features and pricing, of course, so for anyone interested in a smart EV charger, I’d start by reviewing this list.
It’s worth noting that Tesla is reportedly introducing a solar charging feature for its EVs. However, that’s not yet official and I fear it may only be for homes with Tesla Solar. Hopefully, that’s not the case because a Tesla-provided solar charging feature would accomplish Jared’s goal.
I did find one other interesting solution: A mobile app, called Charge HQ, that uses your solar panel power data to tell your Tesla when to charge with excess production. It’s available as a free beta, although it only supports a limited number of solar panel power inverter brands for now. However, it works to add “smarts” to nearly any EV charger. The app connects to your Tesla over Wi-Fi or cellular to tell it when to charge based on your panels producing more electricity than you’re using.
To hear Jared’s question in full, as well as our discussion on the topic, tune in to the Internet of Things Podcast below:
Steve Linthicum says
The need for such a system is diminished in locations like mine here in Southern California, where “time of use” pricing rules. It is much better, at least for me, to charge my EV during the night, where the cost is based on a super off-peak rate charged by the utility. Overproduction provides the utility with the ability to modify how much they can change things to avoid paying a reasonable amount for what your system produces.
William Symons says
Battery back ups can help limit chances of over running the solar system when EV charging and balance out charging over day and night
UNTIL systems get smart enough( even the tesla will complain if power is shut off or reduced while plugged in and charging)
One less technical work-around is to limit the charge amperage on the tesla to below what your solar system averages during the day. And utilize scheduled charging
We had a small 5kw solar system on a large house with pool,as long as we weren’t using the twin a/c’s we could bump down the tesla to around 10-15 amps charge rate at 220 v and rarely go negative on energy production (with pool pump running during the daytime)
Of course if your tesla is not home during the day, a couple Power walls would be the answer for night charging, limiting charge amperage as well to not deplete the backup power and save some for nighttime home needs
Combined, this is sort of energy cost averaging over the course day.
To charge a tesla at 32 or 40 amps at 220v
You’d need a solar system at least 10kw just for the tesla fastest mobile cable charging and more if you have a wall connector on 80-100 amp circuit
Jim Thomas says
I recently read your article titled “Solar Charging an EV Takes Some Pre-Planning or Costly Add-Ons” on the Stacey on IoT website, and I want to commend you for shedding light on the considerations and challenges involved in solar charging electric vehicles (EVs). Your article provides valuable insights into the pre-planning and potential costs associated with harnessing solar energy to power EVs.
Here are a few key points from your article that resonated with me:
1. Energy Requirements: Your article rightly highlights the higher energy demands of charging an EV compared to traditional household appliances. Understanding the energy consumption patterns of EV charging is crucial when designing a solar charging system. By providing readers with an estimate of the energy needed to charge an EV, you lay the foundation for informed decision-making.
2. Solar Panel Sizing: I appreciate your emphasis on the importance of appropriately sizing the solar panel system to meet both household energy needs and EV charging requirements. Calculating the optimal panel capacity based on factors such as daily energy consumption, available roof space, and local solar irradiation levels is vital for ensuring sufficient solar power generation.
3. Battery Storage Considerations: Your mention of the need for battery storage in a solar-charged EV setup is insightful. The inclusion of a battery storage system enables users to store excess solar energy during the day for later use during peak charging times or at night. Exploring the various battery storage options and their costs would further enhance this section.
4. Grid-Tied Systems: Your article touches on the benefits of a grid-tied solar charging system, which allows for a backup energy source when solar power generation is insufficient. The concept of net metering, where excess solar energy is fed back into the grid, and the ability to draw power from the grid when needed offer flexibility and reliability in EV charging. Elaborating on the net metering process and potential cost savings would add depth to this discussion.
5. Cost Considerations: Your mention of the potential costs involved in setting up a solar-charged EV system provides readers with realistic expectations. From the upfront expenses of solar panels and installation to additional costs for battery storage or grid-tie equipment, understanding the financial implications is crucial for individuals considering this eco-friendly charging option.
Overall, your article offers a well-rounded exploration of the pre-planning and costs associated with solar charging EVs. By potentially including real-world examples or success stories of individuals who have implemented solar-charged EV systems, you can provide readers with practical insights and inspiration.
Thank you for sharing this informative content, and I look forward to reading more insightful articles on Stacey on the IoT website.