Here at Transport Evolved, we pride ourselves on being a news site aimed written by journalists and authors who also happen to be electric car drivers, tech enthusiasts and environmentalists with either a big or a small ‘E’. As such, we love hearing from members of the energy or electric car communities who are willing to share their experiences of life with a plug-in car, and today is no exception. By day, Mark Larsen — a Ph.D in Spanish from Yale with an interest in Latin American literature and culture — is Professor Emeritus of Spanish at Utah State University. But when he’s not involved in academia, Larsen is one of Utah’s foremost advocates of electric vehicles and solar energy. At the start of 2014, Larsen wrote an excellent piece on his own website about celebrating three years of powering his home and his car on solar power alone. With his gracious permission, we’ve reproduced it — and his photographs — below. [Ed.]
It was during the OPEC oil crisis of the 1970s that I first began to nurture the dream of driving an electric car, powered with clean, free, renewable energy. It has thus taken me decades to finally realize that dream, but I can now state unequivocally that the results are even better than I imagined.
After three orbits around the “power plant,” my solar array has produced a total of 42,033 kWh of electricity, of which I have used 36,413 kWh to power my home and drive my Nissan LEAF nearly 15,000 miles. I have then “donated” the excess 5,620 kWh to my local utility to sell to my neighbors and likewise help reduce their carbon footprint. Of course, such large numbers are difficult to understand in practical terms, so I have calculated the daily averages since taking delivery of my Leaf to create the following infographic:
Readers will undoubtedly notice that some of my stats are more the exception than the rule. For example, I drive only 23 miles per day, much less than the average commute of 37 miles in the USA. Moreover, dividing my daily miles by the 4.17 kWh reported in CarWings shows that I average a whopping 5.5 miles per kWh. Lest anyone conclude that I am a world-class hypermiler, I should clarify that such high efficiency is actually because few streets in my small community have speed limits above 40 mph. To add a more realistic perspective, the EPA gives the Leaf an official rating of 3.45 miles-per-kWh, and in various blogs and forums most owners claim averages of about 4.
I have to admit that I now feel elated and liberated —even shamelessly smug— whenever I am behind the wheel of my Leaf, knowing that I am driving on emission-free, gas-free, cost-free sunshine. Of course, the initial investment was substantial: to install my array I paid about $3 per watt after incentives. Consequently, because the utility rates are so very low in my area, it would normally take about 20 years for my system to pay for itself. However, since the solar kWh also power my daily driving, the gasoline savings significantly accelerates the payback period. Even driving my few miles per day, and on the unlikely chance that gasoline prices were to remain level, I project that I will recoup my solar investment in about 5 more years. After that… pure gravy! And the good news is that the costs of solar panels have steadily dropped since I installed mine, with the lowest pricetags hovering around $3 per kWh before incentives.
Even still, I recognize that many consumers simply cannot afford to purchase sufficient solar panels to provide all the electricity that they use. After all, it took me years of researching, scrimping, and planning to finally take that giant leap when I built my present home. Nonetheless, if EV owners are willing to invest in a modest array, at least sufficient to charge their vehicles, I can offer some general calculations to assist them, albeit with the disclaimer that they are based upon key assumptions that may or may not apply.
To begin with, let’s assume an average commute of 40 miles per day, and an EV efficiency of 4 miles-per-kWh:
40 miles / 4 miles-per-kWh = 10 kWh per day
When I was researching solar options, installers recommended calculating an average of no more than 5 hours of sunshine per day to accommodate short winter days, long summer days, and bad weather days throughout the entire year:
10 kWh per day / 5 hours = 2 kW array
My solar panels are rated at 230 watts, but different brands come in a variety of sizes and capacities. To err on the conservative side, let’s assume 200 watts per panel:
2 kW / 200 watts = 10 panels
As for price, let’s use the $3 per watt quoted above, be it after or without incentives:
2,000 watts x $3 = $6,000
This is a reasonable ballpark figure of the initial cost to henceforth drive an EV on sunshine, and readers could easily adjust the above formulas to take into account their own daily miles, efficiency, solar prices in their areas, and the available incentives.
Now, to calculate how that investment compares with fuel costs, let’s assume that a gasoline car achieves the U.S. average of 25 MPG, and that the price at the pump is running approximately $3.75 per gallon:
40 miles per day / 25 MPG = 1.6 gallons per day
1.6 gallons x $3.75 per gallon = $6 per day
$6,000 / $6 per day = 1,000 days
1,000 days / 365 days per year = 2.74 years
Ergo, according to the above projections, in less that 3 years the fuel savings alone could conceivably pay for a solar array large enough to power an EV.
What’s not to like? In my mind, the investment is a no-brainer. Nonetheless, I should clarify that it was never my intent to “save money” by installing solar panels and buying an EV. That may or may not be a side benefit as the miles, kWh, and orbits accumulate over time. I simply feel a personal responsibility to do my small part in ending our destructive fossil fool addiction in this world. There is, after all, no Planet B. My effort is just one small straw, but perhaps with enough straws we can break the petrolcamel’s back.
[Reposted with permission from the author’s website.]
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