How Much Does an Electric Car Increase Your Electric Bill?

Electric vehicles are an increasingly common sight, offering a cleaner alternative to gasoline-powered cars. A frequent question for those considering an electric vehicle centers on how it will impact their household electricity bill. Charging an electric car at home adds a new, significant energy load to a residence.

Understanding Your Home Electricity Rates

Residential electricity bills are based on the amount of electricity consumed, measured in kilowatt-hours (kWh). A kilowatt-hour represents the energy used by a 1,000-watt appliance operating for one hour. Your utility company charges a specific rate per kWh.

Many households operate under a flat rate structure, with a single price per kWh regardless of when the electricity is used during the day or night. For example, if a utility charges $0.17 per kWh, that rate remains constant. Alternatively, some areas utilize tiered rates, where the price per kWh changes once a certain consumption threshold is met within a billing period. This structure might charge a lower rate for the first few hundred kWh and a higher rate for subsequent usage.

Time-of-Use (TOU) rates are another common structure, where the cost of electricity fluctuates throughout the day. Under TOU plans, electricity is more expensive during “peak” demand hours, such as weekday afternoons and evenings, and less expensive during “off-peak” hours, like overnight or weekends. Some plans might also include “super off-peak” periods with even lower rates. Identify your specific rate structure and charges by reviewing your monthly electricity bill or contacting your utility provider directly.

Factors Determining Your Electric Car’s Energy Use

The amount of electricity an electric car consumes is influenced by vehicle attributes and driving habits. Vehicle efficiency, often expressed in kilowatt-hours per 100 miles (kWh/100 miles) or miles per kWh, indicates how much energy the car uses to travel a given distance. More efficient models might use around 25 kWh to travel 100 miles, while larger or less aerodynamic vehicles could consume over 60 kWh for the same distance.

The total miles driven annually is a primary determinant of overall electricity consumption. The average American drives approximately 13,500 to 14,263 miles per year. Higher mileage naturally translates to greater energy use and, consequently, higher charging costs.

Battery size, measured in kWh, signifies the vehicle’s energy storage capacity, similar to a fuel tank in a gasoline car. Electric car batteries range from 50 kWh to 100 kWh, with larger capacities offering extended driving ranges. A larger battery requires more energy to fully charge, impacting the total kWh consumed.

Consider charging efficiency losses, as not all electricity drawn from the grid makes it into the vehicle’s battery. Energy is lost during the conversion from alternating current (AC) to direct current (DC) and as heat during the charging process, ranging from 10% to 25% of the total electricity drawn. Real-world driving conditions, such as high speeds, aggressive acceleration, extreme temperatures, hilly terrain, tire pressure or vehicle load, can further affect an EV’s energy efficiency.

Calculating the Electric Bill Increase

To determine the potential increase to your electric bill from EV charging, combine your car’s energy consumption with your home’s electricity rates. First, estimate annual electricity needed for your EV by multiplying annual mileage by the car’s efficiency (kWh per mile), then account for charging losses. For example, if you drive 13,500 miles annually in an EV that uses 0.35 kWh per mile, the car requires 4,725 kWh. A 15% charging loss means you draw approximately 5,559 kWh from the grid (4,725 kWh / 0.85).

With a flat rate electricity plan, multiply the total annual kWh consumed by your rate per kWh. If your rate is $0.17 per kWh, the annual cost would be about $945 (5,559 kWh $0.17). Divide this annual cost by 12 to estimate the monthly increase.

For time-of-use (TOU) rate structures, the calculation is more nuanced, as the cost per kWh changes throughout the day. To estimate how much of your charging occurs during peak, off-peak, and super off-peak hours. For instance, if 80% of your 5,559 kWh charging occurs during off-peak hours at $0.10/kWh and 20% during peak hours at $0.30/kWh, the annual cost would be ($0.10 5,559 kWh 0.80) + ($0.30 5,559 kWh 0.20), totaling approximately $444.72 + $333.54 = $778.26. This provides a precise estimate of charging expenses under varying rate conditions.

Optimizing Charging Costs

Strategic charging practices can minimize the electric bill increase from an EV. If your utility offers time-of-use (TOU) rates, scheduling charging sessions during off-peak or super off-peak hours can reduce costs. These periods, late at night or early morning, have lower electricity demand and thus lower prices. Many electric vehicles and home charging stations allow for scheduled charging, automating this process.

Utility companies provide programs and incentives for electric vehicle owners. These can include discounted TOU rates for EV charging, rebates for installing home charging equipment, or separate meters for EV consumption to isolate those costs. Checking with your local electric utility provider can reveal available programs that might offer savings.

Smart charging technology, found in advanced home chargers and vehicle applications, assists in optimizing costs. These systems can communicate with the electric grid and your utility provider, initiating charging when electricity prices are lowest or when renewable energy sources are abundant. Some smart chargers also offer real-time monitoring of energy use and costs, providing data for managing expenses.

Integrating solar power with electric vehicle charging offers another avenue for cost reduction. Home solar panel systems can generate electricity that offsets your charging needs, reducing reliance on grid electricity for vehicle fuel. While solar panels represent an initial investment, they can provide long-term savings, especially when combined with net metering policies that credit you for excess electricity fed back to the grid.