A Tesla Roadster is charged through a power plug at the Frankfurt Auto Show in Frankfurt, Germany, Wednesday, Sept. 16, 2009.
Electric vehicles are entering the mainstream, with the sporty Tesla having sold 30,000 vehicles so far, and recent moves designed to greatly expand the use of innovative battery technology.
However, as more of these cars hit the road, they place unique strains on the electric grid.
Households with electric vehicles guzzle juice from the grid at night in order to get charged up for the next day, according to a new analysis by Opower, a company that provides cloud-based software to the utility industry. And that could be a problem in the long run.
As electric vehicles go mainstream, utilities may need to continue nudging consumers away from plugging in during peak periods of energy demandAs electric vehicles go mainstream, utilities may need to continue nudging consumers away from plugging in during peak periods of energy demand, the analysis suggests.
The numbers also show that electric vehicle owners are far more likely to have rooftop solar panels than non-electric vehicle owners, which helps offset some of their electrical consumption from coal and natural gas-fired power sources.
At night, the average power consumption of many electric car households is four times higher than typical levels, Opower reports. The company maintains a database of energy use in more than 50 million households, and is in part a consulting firm to electric utilities, working to help them become more energy efficient.
The company's analysis compared data from about 2,000 electric vehicle owners in the western U.S. who charge their cars at night, to data from nearly 100,000 typical households in the West. The data includes electric vehicles other than Teslas, such as the Nissan Leaf and other plug-ins.
Opower plotted the average hourly grid electricity use of electric vehicle owners compared to typical households with gasoline-powered vehicles. Between midnight and 7 a.m., electric car households used three times as much energy than non-electric vehicle owners did. Researchers found a major spike in energy use from electric vehicle households starting at about 10 p.m., peaking around midnight, and then declining toward 6 a.m.
It's no coincidence that the electric vehicle owners in this study tended to charge their cars at night, since their owners signed up with their utilities to secure discounted electric rates late at night, with higher prices during the day. Opower says its data clearly shows that when consumers sign up for such electricity rate frameworks, they take advantage of them, and this data could encourage utilities to roll out more programs like this.
Such arrangements are advantageous for utilities because they help reduce the electricity demand during the day, when overall demand is highest and the risk of overloading the grid is elevated.
Several states have implemented off-peak charging incentives to encourage electric vehicle owners to charge their cars at night, including Texas and Georgia, in addition to the more environmentally conscious California.
Interestingly, Opower found that electric car owners still use more power than their peers during the day. The company explained this by noting that compared to the average household, owners of electric cars tend to be more affluent, with larger houses and more swimming pools than households without such cars. Also, some owners may be plugging their cars in early in the morning or earlier in the evening, missing the low-cost window.
On the other hand, electric vehicle households are also far more likely than typical households to own rooftop solar panels, which cuts their midday energy use and sends power to the grid. In the West, one out of 13 electric vehicle households have rooftop solar installations, compared to just one out of 86 typical households.
If you are an electric vehicle owner without rooftop solar energy, however, it's still likely that you're using more grid electricity than a typical household.
Tags: CLIMATE, ELECTRIC VEHICLES, ENERGY EFFICIENCY, EVS, NISSAN LEAF, OPOWER, TESLA MOTORS, U.S., US & World