Two things are happening to Bay Area homes at once: people are adding EV chargers, and gas appliances are being phased out in favour of electric ones. Both land on the same piece of equipment — the service panel — and a lot of Peninsula housing stock was specified for a very different set of loads.
What decides the answer
Not the number on the panel. The answer comes from a load calculation, which weighs your actual connected loads against the service capacity. Two identical 100A panels can give opposite answers depending on whether the house has a gas range and gas dryer or electric ones.
The calculation looks at square footage, existing large appliances, heating and cooling equipment, and the new load you want to add. It’s a short piece of work and it’s the only honest basis for a quote.
When 100A is genuinely fine
This surprises people, so it’s worth stating plainly: plenty of 100A homes can take a Level 2 charger without a service upgrade.
- If the house still has gas heat, gas cooking and gas drying, there’s often meaningful headroom.
- Many EV chargers can be set to a lower continuous current — a 30A charge rate still adds well over 100 miles overnight, which covers nearly everyone.
- Load-management devices can share a circuit between the charger and another large appliance, so they never draw peak at the same time.
Any of those can be dramatically cheaper than upgrading the service, and we’d rather sell you the small answer when the small answer works.
When you genuinely need the upgrade
- The panel is already full and there’s no room for a subpanel or tandems.
- You’re going all-electric — heat pump for heating, heat-pump water heater, induction range — in which case you’re stacking several large loads and the calculation usually runs out of room.
- The existing panel is a known-defective type. Some mid-century panels have documented breaker failure problems and should be replaced on safety grounds regardless of capacity.
- The service entrance conductors or meter base are undersized or degraded.
The sequencing that saves money
If you’re likely to electrify over the next several years, do the load calculation once, for the end state, rather than for each appliance as it fails. Homeowners who add the EV charger this year, the heat-pump water heater in two years and the furnace after that frequently pay for electrical work three times, and sometimes pay to undo the first round.
Getting the panel right once, with the eventual load in mind, is almost always the cheaper path — even when the upfront number looks worse.
What the job involves
A service upgrade is a permitted job that involves coordination with PG&E for the meter, an inspection, and usually a short planned outage. We handle the permit and the utility coordination rather than leaving you to schedule it, because the sequencing between the inspection and the meter swap is where these jobs typically stall.
Ask for the load calculation before you accept a quote from anyone. If a contractor quotes a panel upgrade without doing one, they’re guessing — and you’re the one paying for the guess.