Charging Plug-In Electric Vehicles at Home
Many drivers of all-electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs) will charge their vehicles overnight at home using AC Level 1 or AC Level 2 charging equipment. Residential equipment frequently will be installed in garages, but outdoor installation and use are also safe, even if the vehicle is being charged in the rain. Outdoor installations require outdoor-rated charging equipment. Charging at a multi-family residential complex requires additional considerations and may be more similar to public charging than to charging at a single-family home.
Installing Charging Equipment in Your Home
Many EV and PHEV owners will be able to meet their daily driving range requirements by charging overnight with AC Level 1 EVSE, requiring no additional cost or installation, provided that a power outlet on a dedicated branch circuit is available near their parking location. For drivers with less regular schedules, or longer commutes, AC Level 2 charging equipment can be purchased. State incentives may be available to help offset the cost.
The most basic AC Level 2 products have standard safety features and status lights. More advanced, "smart" AC Level 2 products have features such as enhanced displays, charging timers, communications capabilities, and keypads.
Installation contractors can inform homeowners if their home has adequate electrical capacity for vehicle charging. Some homes might have insufficient electric capacity for AC Level 2 equipment. Homeowners may have a qualified electrician add circuits to accommodate the capacity needed for AC Level 2 charging.
The City of San Jose, California, has issued requirements for installing an Electric Vehicle Charging System in Single Family Residence: Plan Review and Permitting Requirements that briefly explains the permitting process and location planning for a home EVSE.
Complying With Regulations
Electric vehicle supply equipment (EVSE) installations must comply with local, state, and national codes and regulations. Appropriate permits may be required from the local building, fire, environmental, and electrical inspecting and permitting authorities.
You can learn about related codes and standards on the Codes and Standards Resources page. Electric vehicle charging equipment is considered a continuous load by the National Electrical Code (NEC). Your electrical contractor should understand and apply the current NEC for a safe and code-compliant installation. NEC Article 625 contains most of the information applicable to charging equipment. If possible, consult vehicle manufacturer guidance for information about the required charging equipment and learn the specifications before purchasing equipment or electrical services.
In many areas, a site installation plan must be submitted to the permitting authority for approval before installation.
Jurisdictions that have not yet developed a permitting process for residential EVSE installations can refer to the permitting template.
Electricity Costs for Charging
The fuel efficiency of an all-electric vehicle may be measured in kilowatt-hours (kWh) per 100 miles rather than miles per gallon. To calculate the cost per mile of an all-electric vehicle, the cost of electricity (in dollars per kWh) and the efficiency of the vehicle (how much electricity is used to travel 100 miles) must be known. If electricity costs $0.11 per kWh and the vehicle consumes 34 kWh to travel 100 miles, the cost per mile is about $0.04.
If electricity costs $0.11 per kilowatt-hour, charging an all-electric vehicle with a 70-mile range (assuming a fully depleted 24 kWh battery) will cost about $2.64 to reach a full charge. This cost is about the same as operating an average central air conditioner for about 6 hours. General Motors estimates the annual energy use of the Chevy Volt will be 2,520 kilowatt-hours, which is less than that required for a typical water heater or central air conditioning. To compare the fueling costs of individual models of conventional and plug-in vehicles, see the Vehicle Cost Calculator.
For EV and PHEV charging, the stability and planning benefits of household electricity rates offer an attractive alternative compared to traditional petroleum-based transportation. Learn more from Idaho National Laboratory's report: Comparing Energy Costs per Mile for Electric and Gasoline-Fueled Vehicles.