The shop
Foothill Volt Electric works the EV-and-solar lane in greater Sacramento. Residential charger installs, solar interconnection, the occasional whole-home electrification — heat pump water heater, induction range, panel upgrade to make it all fit. Five techs, two trucks, and Priya Aronson at the helm. She came up through a solar EPC before going solo in 2022.
The customer is usually a homeowner who just bought an EV, or one who's adding solar and a battery. The phone call almost always ends with: "and what's it going to cost to upgrade the panel."
The friction
The answer to that question lives inside a load calc. And the load calc for an EV-and-solar job is the gnarliest version of one.
It's not just dwelling-unit demand. It's dwelling-unit demand minus solar export under the 705.12 rules, plus the charger at the right continuous-load multiplier, plus or minus the EVSE load management setting if there is one, plus the heat pump if it's coming next year, all bumped against the existing service rating. Forty-five minutes of math, easy. An hour if a number didn't add up the first pass.
Most of the time the answer was: yes, you need a panel upgrade. Sometimes the answer was: no, with load management. Customers wanted that answer the same day they called. Priya was giving it to them three days later.
"I lost jobs to faster shops, not better shops."
The switch
Priya moved EV calcs to Breakerbox's Load Calculator in early 2026. The flow now: pull the panel photo, tick the boxes for existing loads, drop in the EV charger amperage, mark whether load management is on the table, add the solar size if there is one. Six minutes.
| Calc type | Before | With Load Calculator |
|---|---|---|
| EV-only on existing service | 30 min | 4 min |
| EV + solar interconnection | 45 min | 6 min |
| Whole-home electrification | 60+ min | 10 min |
The bigger change isn't the speed. It's the confidence. The calc shows the math. If a customer asks why their 100A panel can't take a 48A charger without load management, Priya pulls up the line that pushed it over.
Where they are now
Foothill Volt is closing more jobs the same week the homeowner calls. Priya runs the calc on the truck dashboard before leaving the driveway and texts the customer the answer. Yes-or-no on the panel upgrade. Estimate to follow that night.
The shop's calc-to-close rate is up. The number of "let me get back to you" calls is down. Priya doesn't track either one to a decimal place, but she knows she's not losing the fast-shop bids anymore.
Solar interconnection is the next spot. The 705.12 export-side math is the part she still triple-checks. She's expecting Breakerbox to handle that cleanly enough that she stops triple-checking by summer.