The Solar Electric Vehicle (EV) is a strategy for locking in your energy cost for driving, combining an EV and solar for charging. Making an investment in solar electric power guarantees a fixed cost to charge your EV batteries and save 90% or more on energy over its lifetime as compared to an average gasoline vehicle.

While an EV without solar charging does help reduce the energy cost for driving over gasoline, those costs are likely to rise in the future. Here’s why.

Rising crude oil prices mean higher gasoline prices at the pump. This causes more people to buy EVs and charging them puts pressure on the electrical grid. Utilities must make investments to improve the grid, resulting in customers paying more for electricity.

Let’s compare the costs to power or fuel our vehicles. First, we’ll look at a gasoline vehicle that averages a combined city/ highway thirty (30) miles to the gallon. Assume four dollars a gallon for gas at the pump. Some quick math and we arrive at over thirteen cents per mile in gasoline cost to propel this vehicle down the road.

Next, for an EV we’ll choose a Tesla Model 3 Standard Range. The EPA gives an average power requirement of twenty-four (24) kWh per hundred miles. Assuming the vehicle is always charged during the utility’s off-peak hours, then eight cents per kWh cost is reasonable. Again, some math, and presto, about two cents per mile in electricity to power this EV.

Now invest in a well-situated solar system for two dollars per kW, after tax credits, and this will generate electricity over the system’s warranted and guaranteed 30 year life at four cents per kWh. We’ll assume excess solar power sold to the utility during the day and purchased back by the consumer during off-peak hours is priced the same. So, viola, one cent per mile in solar electric cost to power the same Tesla Model 3.

Now, where this gets really interesting, is over the life of a vehicle. In Arizona, we drive a vehicle an average of 13,000 miles per year. An average vehicle lasts for 12 years. Math again, and we arrive at 156,000-lifetime vehicle miles. Since there is usually a road trip involved from time to time let’s assume that for only 100,000 of those miles the EVs are charged at our property.

When away, EVs will not be able to take advantage of our solar charging and they will get the occasional free charge at a business. Using the off-peak utility rate to calculate this mileage is reasonable.

In the last twelve years, residential electricity rates increased by 17%. If we assume history will repeat itself, then off-peak utility power will cost 9.4 cents per kWh twelve years from now. Applying this to gasoline and the cost would be $4.69 per gallon. Solar power cost remains at four cents per kWh, fixed by the amount of the initial investment.

Putting this all into a massive spreadsheet (actually my smartphone calculator) here are the results. Thirty mpg vehicle lifetime gasoline costs would be nearly $23,000, utility-powered Tesla Model 3 costs $3,400, and solar-powered Tesla Model 3’s battery power is only $2,220.

This estimates that an EV charged by utility power is over 50% more expensive to charge than the same EV charged by solar power. The 30 mpg gasoline vehicle would be a whopping 1000% more expensive fill than a solar EV to charge over its lifetime.

What would you do with the savings?