What Size Electrical Panel Does Your Rohnert Park Home Actually Need?
The honest answer: it depends on what your home is running today and what you’re planning to add. A 100-amp panel was perfectly reasonable when your house was built in 1968 and the biggest load was a window air conditioner. But if you’re looking at an EV charger, a heat pump, or an induction range — or you’ve just been living with nuisance breaker trips for years — that 100-amp service is likely what’s standing in your way. This guide explains how panel sizing actually works, what a load calculation tells you, and how to figure out whether an upgrade makes sense for your specific situation.
Why Panel Size Is a Calculation, Not a Guess
Panel size is measured in amperes — the total amount of electrical current your home’s service entrance can handle at once. The most common sizes you’ll encounter in Sonoma County homes are 100A, 200A, and occasionally 400A for larger or all-electric homes. But the number on the panel label doesn’t tell you whether your home is well-served by it. That requires a load calculation.
A load calculation looks at every significant electrical draw in your home: your HVAC system, water heater, kitchen appliances, washer and dryer, lighting, and any specialty circuits. It accounts for demand factors — the fact that you’re unlikely to be running every appliance at full capacity simultaneously — and arrives at a realistic picture of what your home actually needs. This is the only defensible way to size a panel upgrade. Any electrician who recommends a 200-amp upgrade without doing this math first is either guessing or selling.
At Bright Right Electric, we do the load calculation before we give you a written estimate — and before you spend anything. CSLB #1156335, licensed, bonded, and insured, with 20+ years in the trade. No trip charge to come out and assess your situation.
When a 100-Amp Panel Is Still Adequate
Not every home needs to be upgraded. A 100-amp service is often sufficient for a smaller home — say, under 1,500 square feet — that has gas appliances (range, water heater, furnace) and no EV charger. If your panel is in good shape, properly sized for your current loads, and not one of the recalled brands, there may be no urgent reason to replace it just because it’s old.
That’s a position we’ll actually tell you. If your panel can wait, we’ll say so. Unnecessary work doesn’t benefit you, and it doesn’t build the kind of reputation we’ve spent 20 years earning.
When 100 Amps Isn’t Enough Anymore
The homes we see most often in Rohnert Park, Cotati, and Penngrove that are genuinely running out of capacity tend to share a few common traits:
- Original 100A service from the 1960s–80s with an all-gas home that’s being converted to electric appliances
- An EV charger being added — a Level 2 charger draws 32–48 amps continuously, which is a significant fraction of a 100A service all by itself
- A heat pump or mini-split being installed to replace a gas furnace, adding a large 240V load that wasn’t there before
- A second subpanel being requested for a garage, ADU, or workshop — the math just doesn’t work without upgrading the main service first
- Repeated tripped breakers on circuits that should handle their loads — sometimes this is a wiring fault, but often it’s a panel that’s simply been pushed past its design limits
If you’re in any of these situations, a panel upgrade is worth a real conversation — not because it’s always required, but because staying at 100 amps while adding electric loads creates headaches that don’t go away on their own.
100A vs. 200A vs. 400A: What the Difference Actually Means
A 200-amp service is the standard recommendation for most single-family homes in Sonoma County today — and for good reason. It gives you enough headroom to run a heat pump, a Level 2 EV charger, and a modern kitchen without living at the edge of your capacity. If you’re doing a full panel replacement anyway, going to 200A adds relatively little to the project cost and removes a constraint you might hit in two or three years.
A 400-amp service is less common but comes up in specific situations: large homes over 3,000 square feet with full electric HVAC and multiple EV chargers, properties with a detached ADU or significant outbuilding, or homeowners planning to add solar and battery backup at scale. It’s not the right call for most Rohnert Park households, but when the load math points there, trying to squeeze by on 200A is a false economy.
One thing worth knowing: when we upgrade your panel, we coordinate directly with PG&E for the service disconnect and reconnect. That process, handled correctly, means your power is off for hours — not days. We pull the permit, schedule the inspection, and handle that coordination so you’re not the one on hold with PG&E trying to figure out the process.
The EV Charger Question Changes the Calculation
This is the scenario we’re seeing most often right now across Petaluma, Santa Rosa, and Sebastopol: someone buys an EV, assumes they can just add a charger, and then discovers their panel doesn’t have the spare capacity to support a dedicated 240V circuit without something else giving way.
The right sequence is: load calculation first, then figure out whether you need a panel upgrade before the charger goes in. In some cases, a 100A home can accommodate a Level 2 charger if other loads are modest — but you have to run the numbers. In other cases, trying to force it creates a safety problem and a failed inspection. We do this assessment as part of every EV charger installation we quote, and the estimate you get is for the full scope — charger, circuit, and panel upgrade if the math requires it — before any work starts.
What the Permit and Inspection Process Actually Involves
Panel upgrades in Rohnert Park require a permit from the City of Rohnert Park Building Division. Every job we do is permitted and inspected — that’s not optional, it’s how the work gets done correctly. The inspection confirms that the new panel, service entrance, grounding, and bonding all meet current NEC and California electrical code requirements.
Some homeowners are surprised to learn that unpermitted panel work can create problems when they sell the home or file an insurance claim. Pulling the permit protects you, not just us. It’s one license, one contractor, one permit process — we don’t hand off parts of the job to other trades and hope it gets coordinated correctly.
Frequently Asked Questions
How do I know if my current panel is undersized?
The most reliable sign is a load calculation that shows your demand exceeds your service capacity. Practical signs include breakers that trip regularly under normal use, inability to add a major appliance or EV charger without overloading existing circuits, or a panel with no open breaker slots. A visual inspection alone isn’t enough — you need the math.
Will a 200-amp upgrade handle two EVs and a heat pump?
Often yes, but it depends on your total load profile. Two Level 2 chargers at full draw plus a heat pump in heating mode can push a 200A service close to its limits if you also have electric cooking and a large water heater. A load calculation will tell you whether 200A works or whether you need to look at 400A service, a load-management device, or pre-wiring one charger circuit for a future EV without activating it yet.
Does a panel upgrade require PG&E to get involved?
Yes. Any upgrade that changes your service entrance requires PG&E to temporarily disconnect the utility feed while we do the work, then reconnect it after the city inspection clears. We coordinate that scheduling directly — it’s part of how we run the job, not something we hand off to you to figure out.
Can I add a subpanel instead of upgrading the main service?
Sometimes. A subpanel can solve a space problem — no open slots in the main panel — without requiring a full service upgrade. But it can’t create capacity that doesn’t exist. If your main service is genuinely undersized for your total load, a subpanel just moves the constraint around. We’ll tell you which situation you’re in before recommending anything.
How long does a panel upgrade take?
Most residential panel upgrades in Rohnert Park take one day of on-site work. The longer variables are permit processing time and PG&E scheduling for the disconnect/reconnect — we account for both when we give you a timeline, and we manage that process so there are no surprises.
Ready to Find Out What Your Home Actually Needs?
If you’re unsure whether your panel is holding you back — or you already know it is and want a firm price before committing to anything — we’re straightforward to reach. Bright Right Electric is based in Rohnert Park on Holly Ave, and we serve homeowners across Sonoma County with no trip charge. Every estimate is written, every scope is defined before work starts, and if the job requires a permit, we pull it.
Call us at (707) 791-5552 or request a free estimate online. We’ll do the load calculation, explain what we find in plain language, and give you a clear picture of your options — including the option that your current panel is fine.