Home Battery Calculator

Home Battery Savings Calculator

See what a home battery like the Renon Xcellent or Tesla Powerwall could save you each year by charging overnight at ultra-low rates instead of paying peak prices. Upload your power bill to auto-fill, or enter your usage by hand.

Click to upload, or drag your file here

PDF, photo, or spreadsheet (.csv/.xlsx) of your bill or usage, or enter values manually.

Time-of-use battery savings apply in ON, BC & NS. Other provinces don't yet have a residential overnight rate to arbitrage.

Enter the prices and kWh from your current bill. We compare that against the Ultra-Low Overnight plan, where a battery charges at 3.9¢/kWh overnight and powers your home the rest of the day.

Off-peak (low)
Mid-peak
On-peak (high)

Upload your bill or enter your usage above to see your estimated savings.

How a battery saves you money on time-of-use rates

On time-of-use (TOU) pricing, electricity costs more during peak hours and far less overnight. A home battery like the Renon Xcellent or Tesla Powerwall charges overnight at the ultra-low rate and powers your home the rest of the day, so every kilowatt-hour is effectively bought at the overnight price. Pair a battery with solar to also reduce delivery costs and earn net metering credits.

Ontario Time-of-Use Rates (2026)

Current OEB-regulated prices. The bigger the gap between on-peak and off-peak, the more a battery saves through arbitrage.

Standard Time-of-Use the calculator's default "current rates"

Off-peak Overnight, weekends & holidays
9.8¢/kWh
Mid-peak Shoulder hours
15.7¢/kWh
On-peak Weekday daytime peaks
20.3¢/kWh

Ultra-Low Overnight (ULO) what the calculator compares against

Built for battery & EV owners — the battery charges overnight at the ultra-low rate and powers the home the rest of the day, so usage is effectively bought at 3.9¢/kWh.

Ultra-low overnight 11 p.m. – 7 a.m. (the battery charge window)
3.9¢/kWh
Mid-peak Weekday shoulder hours
15.7¢/kWh
On-peak Weekday 4 – 9 p.m.
39.1¢/kWh

The calculator compares your current prices against buying every kWh at the ULO overnight rate. Upload your bill or edit the values for a personalized estimate.

Rates effective Nov 1, 2025 – Oct 31, 2026 · last verified Jun 4, 2026 (OEB)

Time-of-Use in Other Provinces

Ontario is the only province where time-of-use is the standard residential rate, but a battery pays off anywhere with a cheap overnight rate. The calculator now supports Ontario, BC and Nova Scotia directly — pick your province in the tool. If you're on a TOU plan elsewhere, you can still enter your own tiers.

Quebec (Hydro-Québec)
Opt-in time-of-use for Rate D customers, starting Dec 1, 2026.
Nova Scotia (NS Power)
Optional Time-of-Day rate: off-peak (overnight) ~12.4¢ vs on-peak ~25.2¢ per kWh — select Nova Scotia above to estimate your savings.
British Columbia (BC Hydro)
Optional Time-of-Day: −5¢/kWh overnight, +5¢ on-peak (4–9pm), plus a $5,000 battery rebate from Apr 2026 — select BC above to estimate.
Alberta
Deregulated; some retailers offer time-of-use plans.
NB, PEI, NL, MB, SK & territories
Largely flat or tiered rates; limited time-of-use.

Why add a battery

More than just bill savings

A home battery pays you back in more ways than time-of-use arbitrage alone.

Slash your peak-hour costs

Charge overnight when power is cheapest, then run your home on the battery the rest of the day — so every kWh is effectively bought at the overnight rate. That's the swap this calculator estimates.

Keep the lights on

Ice storms and summer peaks take a toll on the grid. A home battery keeps your essentials running through outages, automatically, in seconds.

Get up to $5,000 back

Ontario's Home Renovation Savings Program (HRSP) offers up to $5,000 toward battery storage, on top of solar incentives.

See battery rebates →

Supercharge your solar

Store daytime solar production instead of exporting it cheap: boost self-consumption, cut delivery charges, and stretch your net-metering credits further.

How net metering works →

Tesla Powerwall & home battery FAQ

Cost, rebates, lifespan, and how a battery pays off on time-of-use rates.

A standalone Tesla Powerwall installed by Xolar in Ontario is about $23,997 before tax (roughly $27,100 with 13% HST). Ontario's Home Renovation Savings Program battery rebate can take up to $5,000 off, bringing the net cost closer to $22,100. Enter your usage in the calculator above for a personalized cost, rebate, and payback estimate.
Ontario's Home Renovation Savings Program (HRSP) offers up to $5,000 back on a qualifying home battery for Ontario homeowners. The calculator applies it to your net cost automatically. You can see every current program on our Ontario rebates page.
Tesla warranties the Powerwall for 10 years. In practice it's expected to keep a meaningful share of its capacity well beyond that, especially under gentle daily time-of-use cycling rather than heavy fast-charging.
One Powerwall (about 13.5 kWh) covers the daily peak-shifting and essential backup needs of most homes. Larger homes, whole-home backup, or pairing with solar can justify a second unit. This calculator models a single battery.
On essentials — fridge, lights, internet, furnace fan — a single Powerwall typically runs a home for most of a day. For whole-home loads including heating or air conditioning, expect a few hours. Pairing with solar lets the battery recharge during an outage and run far longer.
A battery saves by charging overnight when power is cheapest and powering your home the rest of the day. On the Ultra-Low Overnight (ULO) plan that overnight rate is just 3.9¢/kWh, so every kilowatt-hour you'd otherwise buy at peak prices is effectively bought at the overnight price — that swap is what this calculator estimates. A battery pays off fastest when paired with solar, which adds production and delivery-charge savings on top.
Xolar's main battery offering is the Renon Xcellent (16 kWh), a high-capacity battery at a lower installed price. The Tesla Powerwall (13.5 kWh) remains popular for its built-in inverter and app. Compare both using the battery selector in the calculator above.

Make the most of your battery

A battery saves more when it's part of a full system, and the rebate above is just the start.