Many years ago, I wrote extensively on this web site/blog about the multiple intricacies and complexities of what I call “solar offset” charging of an electric vehicle vs. directly filling up with electricity that has been/is being produced by a (home rooftop) solar system connected to the same electrical box into which an EV charger is wired and/or that is connected to the wall-socket into which you’re plugging your EV.
I’m not going to go into that again in detail here, although I will say that I still strongly believe that solar-offset, where one’s (home rooftop) solar system is producing excess electricity during a different time than when you are plugging in your electric vehicle, STILL counts as what I call Sun Miles® for your EV — “Miles driven by an electric vehicle (EV) or plug-in hybrid electric vehicle (PHEV) whose batteries have been charged using solar energy and/or using electricity from kWh credits amassed via solar offset generation.”
Logging into the MyChevrolet app for my Bolt, which shows me when I am charging — and how much time I have to go until a completed charge cycle.
Logging into an Emporia Energy electricity consumption/production app connected to an Emporia Vue unit attached to the main line in the electrical box into which the solar system feeds and via which my Bolt is being fueled. This app shows, in real time, how much excess electricity the 9.4 kW, 30-panel solar system is producing at the same time that my Bolt is drawing charge — usually my Bolt is drawing somewhere around 2,000-2,400 watts, as I charge with a portable EVSE unit at 120 volts and 12 amps. The garage block next to my own garage block here at Highline Crossing Cohousing Community houses the 9.4 kW solar system and the output from this system is patched in to the SAME electric box as the outlet into which I plug my EVSE unit in to charge my car in my garage.
So, for instance, right now, as I write this entry, I can see that our 9.4 kW solar system is producing 5,347 watts MORE than is being drawn from the garages tied into the same electric box. One of those garages is MY garage, and my 2020 Chevy Bolt is plugged in right now! So, I know that every single electron flowing into my Bolt’s battery right now has been produced by solar panels on the garage roof and is the result of local, solar-generated electricity 🌞🙂🌞!
That is SUPER cool to know, and to be able to document: The fact that, right now, in real time, the electricity flowing into the battery of my Chevy Bolt is 100% produced by the 30 solar panels on a neighboring garage block.
I can also use the Emporia app to look at not only a real-time display of the relationship between our solar production and electricity consumption in our HCC garages, but I can look at this data on a minute-by-minute, hour-by-hour, day-by-day, week-by-week, month-by-month, and annual basis.
Clearly, the data that are most relevant to determining whether my Bolt is 100% solar-charging at any given time are the real-time data and the minute-by-minute data.
If solar production (suddenly) drops — due to a passing cloud, general cloudiness, etc. — I can see this as well via the Emporia App.
Now, I am not going in and parsing the data precisely for every single second/minute. However, I can get a very good idea of when, and for how long, my Bolt is filling up 100% on sunshine by looking at the Emporia app. And I do do this — way too often 😉. I LOVE knowing that the electricity in my Bolt’s battery is solar-generated, and locally generated as well. It is a GREAT feeling!
Yes, I do plug in my Bolt at night some of the time, and a significant portion of my charging is sometimes done at night, when the sun is not shining.
At that point, I am relying on solar offset — excess electricity sent into the grid during the day — to offset my electrical use at night. But I am not, technically, filling up directly on sunshine-generated electricity. Instead, I am filling up on electricity generated by Xcel Energy Colorado, whose grid mix is currently 31% renewables, 36% natural gas, and 33% coal.
Even then, though, my fueling is MUCH cleaner than running a car on gasoline AND it is, in my mind, cleaner yet, due to the solar offset that we are creating during the day here via our 9.4 kW system at HCC.
Would I prefer to be filling up, 100%, all of the time, every day, every hour, every single minute, every single second with electricity generated 100% by our 9.4 kW rooftop system here at HCC?
Hell yes, I would!
And I confess that since I am working from home a lot these days thanks to Covid — pretty much five days a week, though that will change to four days a week in January — I actually do often time things, so that, if I can, I have my Bolt plugged in during the daytime hours as much as possible, rather than at night. This, so that I can say more demonstratively that I AM Driving on Sunshine 🌞.
I could add a Tesla Powerwall, or two, to my garage to store solar electricity generated by our 9.4 kW system to be used at night when I plug in my Bolt to help ensure 100% of my electricity is indeed locally generated and solar-produced. However, I don’t have the money for that. Plus, doing that would be complicated: My garage unit is NOT attached to my own townhome, it is metered on a single, collective meter that meters about 30 other garage units and our parking lot lights here at HCC, and none of our garages are wired for 240 volts either.
Now, I know there are some out there who don’t agree with this approach of storing energy from a rooftop system in a Powerwall or other battery rather than sending all the excess immediately onto the grid. There are even some — I remember I got into a heated argument almost 10 years ago on this very web site with a guy who CLAIMED that solar offset is essentially useless — who dismiss the whole electric car/solar pairing entirely 🙄. I also know there are electrical/environmental/energy engineer types out there who understand all of this stuff far better than I do.
But I ALSO know that what I am doing right now — having my Bolt currently plugged in on this partly sunny December day in Littleton, Colo. when our 9.4 kW system is outproducing my consumption: a) makes me feel good; b) is clearly 1,000% percent BETTER, CLEANER, and GREENER than any of the fueling of any of the gas car parked in the HCC garages around me, many of which are being fueled by gasoline/refined oil that was extracted thousands of miles, and even entire oceans, away!
Free, locally produced, solar “gas”: You just can’t beat it!