Powering Your EV Charger with a Standby Generator
As electric vehicle ownership grows, one of the most common generator sizing questions is whether a standby generator can power an EV charger during a power outage. The answer is yes, but proper sizing is critical. An EV charger is one of the largest single electrical loads in a modern home, and adding it to your generator load calculation can push you into a larger generator size than you might otherwise need. Here is how to size your generator for a home with electric vehicle charging.
EV Charger Power Requirements
Level 1 Charging (Standard 120V Outlet)
Level 1 charging uses a standard 120V household outlet and draws approximately 1,400 to 1,800 watts (12 to 15 amps). This load is modest and can run on virtually any standby generator alongside normal household loads. However, Level 1 charging adds only 3 to 5 miles of range per hour, making it impractical for meaningful charging during an outage.
Level 2 Charging (240V Dedicated Circuit)
Level 2 is the standard home EV charging setup. A typical Level 2 charger draws 7,200 watts (30 amps at 240V) to 9,600 watts (40 amps at 240V). Higher-powered Level 2 chargers can draw up to 11,520 watts (48 amps at 240V). This is a substantial electrical load, comparable to running a central air conditioner and an electric water heater simultaneously. Level 2 charging adds 20 to 30+ miles of range per hour depending on the charger and vehicle.
Generator Sizing for Homes with EV Chargers
22kW Generator
A 22kW generator can technically power a 30-amp Level 2 EV charger (7,200 watts) alongside essential household loads. However, if your central AC (3,000 to 6,000 watts) is also running, the combined load may approach or exceed the 22kW capacity. During a summer outage, you may need to choose between running the AC and charging the EV simultaneously. A load-managed transfer switch can automate this by pausing the EV charger circuit when the AC compressor kicks on, then resuming charging when the AC cycles off.
24kW to 26kW Generator
For homes with both central AC and a Level 2 EV charger, a 24kW to 26kW generator provides the headroom needed to run both simultaneously without load management compromises. The Generac Guardian 24kW (Model 7261) and 26kW (Model 7327) are popular choices for EV households. At 24kW to 26kW, you have genuine whole-house coverage plus EV charging without circuit juggling. Kohler offers comparable models in this range with the added benefit of quieter operation.
28kW Generator
For homes with multiple EVs, a 48-amp charger, large HVAC systems, or all-electric homes, a 28kW generator like the Generac 7282 or 7329 provides maximum residential capacity. This size handles every household load including simultaneous EV charging and AC operation with significant capacity to spare.
Practical Outage Charging Strategy
During an extended outage, you likely do not need to fully charge your EV every night. A strategic approach is to charge during off-peak generator load hours (overnight when AC demand drops) and charge only enough to cover your daily driving needs rather than filling to 100%. Even 2 to 3 hours of Level 2 charging overnight adds 40 to 90 miles of range, which covers most daily commutes. This approach works well with a 22kW generator because the AC is cycling less frequently during cooler nighttime hours.
Future-Proofing Your Generator Purchase
If you do not currently own an EV but plan to purchase one in the next few years, consider sizing your generator for the future EV load now. The cost difference between a 22kW and 24kW or 26kW generator is typically $1,000 to $2,500 in equipment, which is far less than the cost of replacing an undersized generator later. Buying the right size upfront is always more economical than upgrading after installation.
IB Lighting carries standby generators from Generac and Kohler in sizes from 10kW to 28kW, plus Level 2 EV chargers from Tesla, Lectron, and Greenworks. Call (800) 674-9019 for help sizing a generator for your EV-equipped home. Free freight plus insurance included.