🌞 Solar Panel Size Calculator

Advanced system sizing · Worldwide standards · Localized peak sun hours
☀️ Adjusts daily peak sun hours
Hours of full sun equivalent per day (location specific)
USA typical household: ~886–1000 kWh/month. Worldwide avg varies.
Recent years = higher wattage panels. Auto-updates wattage below (adjustable)
Modern residential panels: 400W–550W. Auto-set based on model year.
Inverter, wiring, soiling, temperature losses. 10–20% realistic
🇺🇸 Factor insights (USA standards)
• Avg consumption: 886 kWh/month (EIA).
• Sun hours: Southwest 5.5+, Northeast ~4.0.
• Modern panels (2025+) reach 22% efficiency.
• System derating: 14% accounts for real-world conditions.
⚙️ REQUIRED SYSTEM SIZE (DC)
— kW
Solar array capacity needed
📐 NUMBER OF PANELS
—
📏 ROOF AREA (m² / ft²)
— m²
— ft²
🌎 ANNUAL GENERATION
— kWh
Coverage: — of consumption
📊 Daily Energy Balance (kWh)
Consumption vs. Solar generation (adjusted for losses)
💡 Component breakdown
Daily need: — kWh | Peak sun hours: — h
Efficiency factor: —% | Panel wattage used: — W

📘 How to use this solar panel size calculator

1️⃣ Select your Country/Region to automatically set typical peak sun hours (adjustable).
2️⃣ Enter your monthly electricity consumption (kWh) – check your utility bill.
3️⃣ Type the model year of solar panels you plan to use (e.g., 2025, 2026) – this suggests a modern panel wattage, but you can override.
4️⃣ Adjust system losses (shading, inverter, dirt) – 14% is a solid default.
5️⃣ Click “Calculate” → Get system size, number of panels, required roof area, annual generation and a comparison graph (daily usage vs solar output).
✔️ Works worldwide thanks to adjustable sun hours & international references.

🔧 Expert Tips for accurate solar sizing

  • Use 12 months of utility data for best monthly average (seasonal variation matters).
  • In the US, South-facing roofs with tilt ~30° maximize yields; adjust peak sun hours accordingly.
  • Higher wattage panels (2024+) reduce required roof area — model year field reflects this trend.
  • Always add 10–15% extra capacity for future energy needs (EV, heat pump).
  • Check local shading: trees or chimneys can increase effective system losses beyond default 14%.
  • For off-grid systems, increase battery storage and oversize array by 20%.

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