Use of an Electric Vehicle Greatly Reduces the Return on Investment for a Solar Array

July 29, 2015
Session W2A: PV, the Future of Transportation and the Grid — Room 104
9:45 am  -  10:45 am

Because of relatively lower electricity costs in Ohio and the mid-west, the return on investment for a residential solar array is in the range of 12- 14 years. For all but the most environmentally conscientious, This is too long of a period to consider installing a solar array. A little published fact is that if the power from a solar array is used to charge an electric vehicle the return on investment is greatly reduced if the savings over gasoline is used as the criteria. Electric vehicles, (EV) are 3 times as efficient as gasoline powered vehicles. While there are a growing number of EVs on the market there are only 3 readily available in the mid-west. They are the Nissan Leaf, the Chevrolet Volt and the Tesla. Using the EPA ratings for watts/mile of the electric vehicle and comparing it to the ratings for miles/ gallon of the comparable gasoline powered vehicle the amount of gasoline saved can be calculated. This multiplied times the cost of gasoline gives annual cost of gasoline that can be allied to offset the cost of the solar array. With the calculated annual power consumptions of the EV the required size, the cost of the required solar array can calculated. If the cost of gasoline is $3.50/ gal the solar array return on investment for a Nisan Leaf is 5.2years. The Chevy Volt is 5.4 years and a Tesla S is 3.9 years. If the cost of gasoline is reduced to $2.50/ gal the return is 7.2 years for the Leaf,7.53 years for the Volt and 5.5 years for the Tesla. When gasoline is at $2,50/ gal the return on investment for a solar array is about one half the time as compared to savings of electricity saved and with higher gasoline costs which are inevitable the return time is even shorter. Another benefit of powering an electric vehicle from electricity generated from the sun is the reduction carbon released into the atmosphere. The annual carbon reduction per year for the 3 vehicles considered is 3.37 ton of carbon per year for the Nissan Leaf, 4.54 tons of carbon for the Chevy Volt and 6.55 tons of carbon for the Tesla S. This results from the fact that according to US DOE gasoline emits 8.91 kg of carbon per gallon. Currently most electric vehicles are significantly more expensive than the equivalent gasoline powered vehicles. This difference is currently reduced by the $7500 income tax rebate offered by the US government on the purchase of a qualifying EV. Even with the rebate most vehicles are still more expensive than their equivalent counterpart. With lower cost vehicles, the difference in the range of $3-4000. This amount adds 2-4 years to the return on investment , still making the return quicker than if used against the cost of electricity. The paper will contain the tables and calculations to back up the conclusions.