Whether you need a panel upgrade for an EV charger comes down to a load calculation — your panel's existing connected load against its rating, with the EV circuit added at 125 percent of its draw. A modern 200-amp service with headroom usually carries a Level 2 circuit as-is. A full or undersized panel may need a service upgrade, a subpanel, or load management first. The rating on the panel door isn't the deciding number; the available capacity is.
The honest answer: it depends on the load calc
There's no universal yes or no, because two Bend homes with the same panel rating can have very different available capacity depending on what's already connected. The only honest way to know whether your panel carries a Level 2 circuit is a load calculation — totaling the existing load against the service rating and adding the EV circuit. That's why we open the panel before promising any amperage, instead of quoting a charging speed sight unseen.
The good news: many homes are fine. The frustrating news: you can't know from the rating on the door, and an installer who promises a 48-amp circuit before opening the panel is the one you don't want.
What the load calculation checks
A load calculation totals your home's connected electrical load — the range, dryer, AC, water heater, and general circuits — and compares it to the service rating, usually 100A or 200A. The EV circuit is added at 125 percent of its draw because it's a continuous load. If the total stays within the service capacity, the panel carries the charger; if it pushes over, something has to give. It's arithmetic on real numbers, not a guess.
Two physical things also matter alongside the math: whether the panel has open breaker spaces, and whether the bus and main breaker can take the added load. A panel can have capacity on paper but no slots, which is its own fixable problem.
Can a 100-amp panel handle an EV charger?
Often, yes — with a right-sized circuit and sometimes a smaller amperage than the maximum. Plenty of homes charge fine on a 100-amp service as long as the load calc supports it. A 100-amp panel already carrying a lot may only have room for a 30- or 40-amp EV circuit, which is still real Level 2 speed for most drivers. If the calc shows no room, that's when an upgrade or load management enters the picture. The rating doesn't decide; the math does.
Upgrade the service or add a subpanel?
If the load calc says the panel can't carry the EV circuit, there are two main fixes. When the main service itself is undersized, a service upgrade — often to 200 amps — is the answer, coordinated with the utility, permitted, and inspected. When the service has capacity but no open slots, a subpanel adds circuit spaces more simply and often more cheaply. We size the fix to the actual problem rather than defaulting to a full service change.
When load management is the better fix
Load-management equipment lets an EV circuit back off when the rest of the house is drawing heavily, so the charger and the existing loads share the service without overrunning it. It can fit a charger onto a panel that couldn't carry a full-amperage circuit otherwise, and it's especially useful for a second charger. It isn't always the right call — for a chronically maxed panel a real upgrade is better — but it's a genuine alternative worth weighing.
The bottom line: get the load calc first, then choose. If you're wiring for two cars or an ADU, the math changes again, and the right amperage to ask for is its own question — see what amperage EV charger do I need. When the answer is an upgrade, our panel and service upgrade service sequences it with the EV circuit as one job.