Kerry Murphey's picture

How Buying EVs Leads to Solar, and Charging My Volt In Real Time

About a year and a half ago I was flipping around the TV and caught the last half of a Toyota RAV 4 EV commercial. My wife and I had been shopping around for cars for the past six months and EVs were not even a consideration. This was now intriguing to me so I did what anyone these days would do, headed to YouTube to see the rest of that commercial.

From that point I was hooked on the whole Electric Vehicle concept, and was now all in. We leased our RAV 4 EV in February 2014 for my wife's 100 mile round trip commute to work. The original goal was to save money on "fuel" and to save her time with HOV lane access. In both instances the new experience has delivered. My wife's commute costs have gone from $18/day in gasoline to about $2 in electricity, and she saves roughly 40 minutes each way in the carpool lane. Win-win.

Now that I had an electric car and of course joining multiple Facebook groups for a sense of community and information, the avalanche of ideas came pouring in. Next on my checklist was getting a solar PV system on my roof since I live in Southern California where we seem to have a lot of free energy raining down from the sky, unlike water unfortunately, but that’s a different article.

Getting a solar PV system is not an easy purchase by any means, it takes extensive research, planning, approvals and other mind numbing activities that really should be streamlined by someone. We decided on getting a 5.5 KW system, using 20 SolarWorld panels and Enphase micro inverters under a power purchase agreement.

Check out my solar production in real time here.

Our new solar PV system was installed in May of 2014, and we of course immediately began seeing positive results. On sunny, 80 degree days the system generates about 35 KWs per day, depending on the time of year. Now that we are one year into having our solar PV system, the final number for our yearly bill will be about $275. To put that into perspective, previously our hottest month of the year, with the heaviest AC usage was September, which typically would cost about $550, without any EVs! We should see our return on investment in just about 2 years if you include our lack of purchasing gasoline / commuting costs into the equation.

In June of last year, I sat back and observed having our RAV 4 EV, and our new solar PV system and realized that I needed (wanted) an EV now. To Facebook I went, joining the various other groups to find out what car would suit my needs. Of course I wanted a Tesla, but I also wanted to feed my kids, so that was not going to work. I needed a long range car for road trips since the RAV 4 EV is awesome on shorter trips (140 miles or less), but not practical for going to Las Vegas for instance.

The 2014 Chevrolet Volt was perfect for my needs since I work from home, and rarely dip into the gas tank. There seemed to be a common question popping up on the Volt Facebook groups I noticed, why can’t you add solar panels to the roof of an EV to help charge the car? A few months into owning the Volt, a lightbulb went off in my head that I just had to test out. Could I charge the Volt in real time during peak sunlight hours with the panels on my roof? The maximum charging rate of the Volt is 3.3kw while charging on our Clipper Creek L2 EVSE. Our solar PV system pumps out between 4-4.5kwh during the hours of 10am and 2pm, so on paper this should work.

On a nice warm, but not hot, sunny Southern California day I tested out this theory with great success. My system was running at at 4 KW at around 10am, so I plugged my Volt in with about 25% remaining on the battery and started charging. Watching my electric meter, as I often do now because it’s fun for some reason, it showed that the house along with the car was using up the full 4 kWh and holding steady. As the morning turned to afternoon, we were actually sending a little bit back to the grid, while still charging the Volt, and the house’s usage combined.

Roughly three hours later, the Volt was finished charging and I thought to myself, How cool is this? I was literally charging up my Volt using only sunlight, and thus my next trip would essentially be running on the power of the sun as well. Generating power from my own rooftop is quite an interesting concept, but it took 20, 275 watt panels to get the job done in real time. So to answer the ongoing question of putting solar panels on the roof of an EV in order to help charge the battery, I suppose the answer is not yet. Technology is moving at a rapid pace, and I guess at some point we will see a day where this is possible. For now, unless you tow an 18 wheel hauler with solar panels in the back of your EV, it’s not going to do much charging. It’s not practical, likely would void the warranty and just look goofy.

As far as charging the Volt with my solar PV system on a regular basis like this, it’s actually not practical or economical either. Our rates from Southern California Edison, on their TOU (Time of Use) plan allows us to charge our EVs overnight at 11¢ kWh from 10pm-8am, while we generate power during the day at 46¢ kWh, sending it back to the grid, making this a better way to use the system and for EV charging.

Kerry Murphey is a syndicated motorsports radio host
Check him out at The Final Lap or can be reached on Facebook or Twitter.

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Nice article, I'd love to be able to do this with my Volt someday! Pet peeve: please look into the correct usage of kW and kWh, the article has it wrong at least half the time.

Good article. Shows just how practical solar and EVs really are. Charge On.