What's the difference between a panel upgrade and a subpanel?

A panel upgrade increases your home's total electrical capacity — for example, replacing a 100-amp main panel with a 200-amp one — so you can run more equipment safely. A subpanel adds more circuit space by branching off your existing main panel, without increasing total capacity. In short: upgrade for more power, subpanel for more breaker slots when you still have capacity to spare.

Do I need a panel upgrade for an EV charger or heat pump?

Maybe. A Level 2 EV charger or an electric heat pump adds a substantial load. If your existing service has enough spare capacity, a subpanel or a single new circuit may be all you need. If your panel is already near its limit, a full upgrade is what lets you add the equipment safely. A load calculation tells us which it is.

When is a subpanel the right choice?

A subpanel makes sense when your main service has enough total capacity but you've simply run out of breaker slots — for instance, finishing a garage, adding a workshop, or wiring a detached structure. It's a smaller, often more cost-effective project than a full service upgrade. [GATHER: confirm typical local price ranges for panel upgrades vs. subpanels.]

How do I know my panel is maxed out?

Frequent tripping, a full panel, flickering lights, and an old 100-amp service are the tells. See signs your electrical panel needs an upgrade .

Does this work require a permit?

Yes — both panel upgrades and subpanels require an electrical permit and inspection in California. See do you need a permit for an electrical panel upgrade? We handle it.

Panel Upgrade vs. Subpanel: Which Do You Need?

Short answer

Choose a panel upgrade when you need more total power (e.g. 100A → 200A) for an EV charger, heat pump, and modern loads. Choose a subpanel when your service has capacity left but you're out of breaker slots. A load calculation tells us which one your home actually needs.

Two different problems

People often use "I need more power" to describe two distinct situations. One is running out of capacity — your service simply can't supply more amps safely. The other is running out of space — you have plenty of capacity, but no open slots to land another breaker. The fix is different for each.

Side-by-side comparison

Factor	Panel upgrade	Subpanel
What it solves	Not enough total power	Not enough circuit slots
Service capacity	Increases it (e.g. 100A → 200A)	Stays the same
Best for	EV + heat pump + modern loads	More circuits, plenty of capacity left
Adds circuit space	Yes (new larger panel)	Yes (branches off the main)
Typical scope	Larger — utility coordination	Smaller — extends existing service
Permit	Required + inspection	Required + inspection

When a panel upgrade is the answer

Upgrade when your total capacity is the limit: an older 100-amp service that's near its ceiling, plus plans for an EV charger, a heat pump, or other major electric loads. Increasing to 200-amp service gives the whole home headroom and the slots to add circuits — it's the future-proof move when you're electrifying.

When a subpanel is the smarter spend

A subpanel wins when you still have capacity but need more circuits in a specific area — a garage, workshop, addition, or detached building. It branches off the main panel to add breaker space without the cost and utility coordination of a full service upgrade. There's no universal winner; there's a right fit for your loads.

Why guessing backfires

Adding a big load to a panel that can't support it is a fire and equipment risk, and over-buying a 200-amp upgrade you don't need wastes money. The honest answer comes from a load calculation — measuring your real and planned demand against your service — not a rule of thumb.

How to decide

Start with the warning signs, and if you're adding a charger, see EV charger options. Then request a free quote with a real load calculation, or browse our electrical services. Comparing bids? Get a free 2nd opinion.