A doubled electric bill has a cause. It is always traceable, and it is almost always one thing. Not a combination of small things. The goal of this guide is to get you to that one thing in the least amount of time.
Start with the simplest question before anything else.
Step 1: Was It Actually a Usage Spike or a Rate Change?
Before you start pulling appliances apart, check your kWh consumption, not your dollar amount.
Log into your utility’s account, find the usage history, and compare kWh consumed this billing period to the same period last year. If your kWh is flat but your bill is 25% higher, California’s recent rate increases explain the whole thing. PG&E raised residential rates substantially in early 2026, and SDG&E has increased rates every year for several years running.
If your kWh actually doubled, you have a real usage spike, and the rest of this matters. (To rule out a rate change, you can check your plan’s current per-kWh prices in the US electricity rate database.)
Want to skip the manual detective work? Answer a few questions and get the most likely cause of your spike.
Diagnose my bill spike →Step 2: Look at the Shape of the Spike
Your utility’s smart meter data (available through “Green Button” on PG&E’s site, similar portals for SCE and SDG&E) shows your usage in 15-minute or hourly intervals. Download it and look at the daily usage totals.
Two patterns tell you different things:
One or a few days with extreme spikes: Something turned on and didn’t turn off. Water heater element failure is the most common cause I see. A failed thermostat keeps the heater running continuously instead of cycling. Pool pumps running on broken schedules show the same pattern.
Elevated usage every day, consistent: A new continuous load was added. An extra refrigerator, a new EV charger, someone moving in, or a HVAC unit running much more than before.
If you see high usage even at 3am when nothing should be running, that’s almost always a water heater, a chest freezer, or a base-level HVAC issue.
Step 3: The Most Likely Causes, Ranked
After working through a lot of bill spikes, here’s roughly how often each cause shows up:
1. Someone started charging an EV at home
A Tesla on a Level 2 charger adds 300-600 kWh/month. That alone can double the bill for an average apartment. The fix isn’t to stop charging. Switch immediately to a TOU-EV plan (PG&E EV2-A, SCE TOU-D-PRIME) and charge after 9pm, where you can get rates as low as $0.14–$0.16/kWh instead of $0.40+.
2. Electric water heater failure
A failed heating element or thermostat causes continuous running. The symptom in interval data is high usage (10–15 kWh) overnight when you’re asleep. If your hot water is also running out faster than usual, or the water is scalding, this is the culprit.
3. New occupant or changed schedule
A person working from home, a family member moving in, or a college student returning adds 60–150 kWh/month for their devices and HVAC load. Not enough to double a large household’s bill, but enough to double a small one.
4. Old chest freezer or second refrigerator coming online
A pre-2000s chest freezer can draw 150–200+ kWh/month on its own. If one was moved to the garage or plugged in for the first time, it shows up as a persistent baseline elevation.
5. Air conditioning season starting (or an AC unit replaced with a larger one)
The most obvious summer cause. A central AC system running several hours/day on a hot month can add 500–800+ kWh. If your previous bills were from a mild month, this comparison is misleading. Compare June to June, not June to March.
The Smart Plug Test
If the interval data points to a continuous overnight load and you can’t identify it, use a smart plug with energy monitoring. Kasa EP25 is $20 and gives you real-time and historical draw data. Plug suspected appliances in one at a time and check 24-hour consumption.
Priority order: electric water heater circuit (if accessible), garage refrigerator/freezer, any appliance with a heating element, pool pump controller.
When to Call the Utility
If you’ve checked every appliance and the interval data still shows usage you can’t account for, request a meter accuracy test from your utility. They’re required to perform it at no charge in California. Meter failures are rare but happen. When they do, the utility owes you back-billing adjustment.
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Dana Whitmore
Energy Engineer & Billing Analyst · Optiwatt Energy Advisor
Dana has spent the past three years analyzing residential electricity billing data across PG&E, SCE, and SDG&E service territories. She's reviewed billing records for thousands of California households, and built the simulation engine that powers this site's rate-plan comparisons. She holds a degree in Electrical Engineering and lives in the Bay Area.