The Time-of-Use rate optimizer generates an optimal 24-hour schedule for EV charging and home battery discharge based on your utility's TOU rate tiers. It shows the cheapest charging windows and calculates daily savings compared to charging at random times.
Utility TOU Rates
Devices
Optimal Schedule & Savings
Configure your TOU rates to see optimal schedule.
24-Hour Rate Timeline
How TOU Rate Optimization Works
Time-of-Use optimization shifts flexible electricity loads (EV charging, battery charging) to the cheapest hours and schedules discharging for the most expensive hours. With a spread of $0.28/kWh between peak and off-peak on California PG&E's EV2-A rate, a home with one EV and a home battery can save $1,500-$2,500/year.
Typical TOU Rate Structures
Most major utilities now offer TOU rates for residential customers. Common structures: PG&E EV2-A: Peak $0.48/kWh (4-9 PM), off-peak $0.11-$0.14/kWh (midnight-3 PM). SDG&E TOU-DR1: Peak $0.52/kWh, super off-peak $0.15/kWh. Eversource MA: Peak $0.23/kWh, off-peak $0.12/kWh. Xcel Energy CO: Peak $0.18/kWh, off-peak $0.08/kWh. Check your utility's rate schedule or call them to ask about available TOU programs.
Implementing EV Charge Scheduling
Most modern EVs have built-in charge scheduling via the car's app or touchscreen. Set a "departure time" (e.g., 7 AM) and the car will back-calculate when to start charging to be ready. Alternatively, many Level 2 chargers (ChargePoint, Emporia) have app-based scheduling. Set the start time to your off-peak window start (typically midnight) and the car will only draw power during cheap hours.
Battery Discharge Strategy
A home battery should discharge during peak hours to power household loads instead of drawing from the grid at high rates. Most systems (Tesla Powerwall, Enphase IQ, SolarEdge) have an automatic TOU mode — enter your peak window in the app and the battery will discharge automatically during that window. Without manual configuration, batteries default to backup-only mode and don't arbitrage TOU rates.
FAQ
Is this TOU rate optimizer free?
Yes, completely free with no signup required. Enter your utility's peak, mid-peak, and off-peak rates with their time windows to generate an optimized daily schedule.
What is a TOU (Time-of-Use) electricity rate?
Time-of-Use rates charge different prices per kWh depending on the time of day. Peak rates (typically 4-9 PM on weekdays) can be $0.30-$0.55/kWh, while off-peak rates (midnight-6 AM) may be $0.08-$0.14/kWh. The price difference creates an opportunity to save by shifting EV charging and battery discharge to low-cost periods.
When should I charge my EV on a TOU rate?
On most TOU plans, the cheapest window is midnight to 6 AM (off-peak). Set your EV to charge at midnight using a scheduled departure time in your car's app or charger settings. This avoids peak rates and often aligns with utility grid demand for renewables, which are highest at night in wind-heavy grids.
Can I save money without a home battery?
Yes — simply scheduling your EV charging to off-peak hours is one of the biggest TOU savings strategies. On a $0.28/kWh rate difference and 10kWh of daily charging, you save $1,022/year with zero hardware cost. With a home battery, you can also discharge stored off-peak energy during peak hours for household loads.
How much can I save with TOU optimization?
Savings vary widely by utility and usage. A typical home with one EV (50 miles/day) and a home battery (10kWh daily cycle) on a California-style TOU plan ($0.45 peak, $0.13 off-peak) can save $1,500-$2,500/year compared to flat-rate charging at average rates. Homes in states with flat-rate electricity see minimal TOU benefit.
Is my data safe?
Yes. All calculations run in your browser. No data is transmitted or stored.