Solar Panel Charge Time Calculator (Canada)

How to use this calculator

Enter six values and the calculator returns charge time in hours and days plus a verdict on whether your array is sized correctly:

1. Battery capacity (Ah) — printed on the case. A typical Canadian RV battery is 100–125 Ah AGM; an off-grid cottage bank is 400–800 Ah; a remote First Nations community generator-replacement system can be 2,000+ Ah.
2. Battery voltage — 12 V for vehicles and small RV systems, 24 V or 48 V for cottages and whole-property setups.
3. Depth of discharge (%) — how empty the battery currently is. 50% is the standard lead-acid daily target; LiFePO₄ tolerates 80–100%.
4. Panel total wattage — sum of every panel’s STC rating (e.g. four 200 W panels on a cottage roof = 800 W).
5. Peak sun hours per day — for your location and season (see the FAQ for province-by-province averages).
6. System efficiency (%) — leave at 75% unless you have a clean MPPT plus LiFePO₄ setup, in which case 85% is reasonable.

The formula

The calculator uses the energy-balance equation that CanmetENERGY and every CSA C22.1-compliant designer applies:

energyNeeded (Wh) = batteryAh × batteryV × (depthOfDischarge / 100)
dailyEnergy (Wh)  = panelW × peakSunHours × (efficiency / 100)
days              = energyNeeded / dailyEnergy

A worked example for a typical Ontario cottage in July:

• 200 Ah × 12 V × 0.50 = 1,200 Wh to recover from 50% DoD
• 400 W × 5 h × 0.75 = 1,500 Wh delivered per day
• 1,200 ÷ 1,500 = 0.8 day of clear sun (about 6.4 hours)

And for the same cottage in December:

• 200 Ah × 12 V × 0.50 = 1,200 Wh to recover
• 400 W × 1.7 h × 0.75 = 510 Wh delivered per day
• 1,200 ÷ 510 = 2.4 days of clear winter sun — and December rarely strings together two clear days, so plan for generator backup or a much larger array.

Charge time reference table (Canada)

Common scenarios using 4 peak sun hours (national year-round average) and 75% system efficiency, starting from 50% depth of discharge:

For winter operation, multiply the charge time by 2–3× across most populated Canada.

Common Canadian scenarios

RV and trailer

A 200–400 W roof panel and a single 100–200 Ah AGM or LiFePO₄ battery is the standard Canadian RV configuration sold by Canadian Tire, Renogy and Costco. With a 50% nightly draw from a fridge and lights, 200 W keeps pace in summer; 400 W gives headroom for shoulder-season camping in BC or Quebec.

Off-grid cottage (seasonal use, May–October)

Battery sized for 2–3 days of autonomy, panel array sized to recharge in 2 days of average summer sun. A 400 Ah / 12 V bank with 800 W of panels suits a typical Muskoka or Eastern Townships cottage running lights, a 12 V fridge and a propane stove. See the solar wire size calculator for the long ground-mount-to-cabin runs typical at lakefront properties.

Year-round off-grid (rural BC, Yukon, Northern Ontario)

48 V system voltage, 800+ Ah lithium battery, 6–10 kW of panels and MPPT charge controllers. At this scale you size for one-day recovery in worst-case (December) conditions, which means the array is 3–4× oversized for summer. Most year-round Canadian off-grid setups still need a 5–10 kW propane or diesel generator for January–February cloudy stretches.

Backup battery for grid-tied (BC Hydro, Hydro Quebec net metering)

You usually don’t size the panel array for battery recharge — you size it for daily home consumption. Charge time only matters during outages, common in BC during winter windstorms and in Quebec during ice storms. A 5 kWh battery sized for 24 hours of essential loads (fridge, internet, furnace fan) is the standard backup target.

What the calculator deliberately ignores

• Solar irradiance variation across the day. Real production curves are a bell shape, sharply asymmetric in Canadian winter when the sun rises around 8 am and sets by 4:30 pm. The “peak sun hours” abstraction handles this for energy totals.
• Battery state-of-charge taper. The last 10–20% of a lead-acid charge cycle takes the same time as the first 80%. Add 1–2 hours for absorption and float.
• Charge-rate limits. Lithium accepts up to 1 C (a 100 Ah battery takes 100 A). Lead-acid is typically 0.1–0.2 C. If your array delivers more than the battery accepts, the surplus is wasted.
• Snow cover. A panel buried under 5 cm of snow produces nothing. Latitude + 15° tilt helps shed snow naturally; below that angle, manual brushing (with a soft brush, never a metal scraper) is required.

Sizing rule of thumb (Canada)

If you want one-day recovery from a normal night’s discharge:

• Panel watts ≈ Battery Wh × 0.6 — Prairie summer (Calgary, Saskatoon, Winnipeg): 5+ peak sun hours
• Panel watts ≈ Battery Wh × 0.7 — Ontario/Quebec summer: 4.5 peak sun hours
• Panel watts ≈ Battery Wh × 1.5 — year-round annual average: 3–4 peak sun hours
• Panel watts ≈ Battery Wh × 3.0 — winter design (December across populated Canada): 1.5 peak sun hours

For dependable Canadian off-grid power, multiply panel watts by a further 1.5–2× to handle multi-day overcast or snow-covered periods.

Cost context (Canada 2026)

Typical equipment pricing in 2026 from Renogy Canada, Costco and HomeStars-listed installers:

• 100W mono panel + PWM controller + 100Ah AGM: CAD $400–$580
• 200W panel + 20A MPPT + 100Ah LiFePO₄: CAD $1,200–$1,650
• Off-grid 6 kW array + 13 kWh lithium + inverter, installed: CAD $32,000–$48,000 (HomeStars 2026 cottage average)
• Grid-tied 6 kW rooftop, installed: CAD $18,000–$24,000 before federal Greener Homes Grant

The federal Canada Greener Homes Grant offers up to CAD $5,000 plus an interest-free loan up to CAD $40,000 for grid-tied installs — verify current program status with NRCan before quoting clients.

Sources

• NRCan PVWatts Canada — peak sun hours and yield by postal code
• CanmetENERGY RETScreen — Canadian off-grid system modelling
• CSA C22.1 Canadian Electrical Code — wiring and code compliance
• HomeStars 2026 Solar Cost Index — installed cost benchmarks by province