Solar Rooftop Calculator

Our calculator provides estimates based on international solar irradiance data and industry-standard formulas. Accuracy varies by ±10-15% due to local factors like microclimate, roof orientation, shading, and specific equipment efficiency. Peak sun hours are based on NASA and meteorological data for each region. For precise calculations, consult with a local certified solar installer.

Key factors include: roof orientation (south-facing in Northern Hemisphere, north-facing in Southern Hemisphere), tilt angle (typically latitude ±15°), shading from buildings/trees, temperature (panels lose ~0.4% efficiency per °C above 25°C), dust and pollution levels, altitude, and local weather patterns. Our calculator accounts for typical system losses of 15-30% based on regional conditions.

Higher wattage panels are typically larger: 300W panels (~17.6 sq ft), 400W panels (~19.6 sq ft), 500W panels (~21.8 sq ft), 600W panels (~24.1 sq ft), and 700W panels (~26.4 sq ft). The calculator automatically adjusts roof area requirements based on selected panel wattage. Higher wattage panels may be more cost-effective despite requiring more space.

Peak sun hours represent equivalent hours of 1,000 watts/m² solar irradiance daily. They vary significantly: Desert regions (5.5-6.0 hours), Mediterranean climates (4.5-5.2 hours), Temperate regions (3.0-4.0 hours), Northern Europe (2.8-3.5 hours). Equatorial regions have consistent year-round values, while higher latitudes show seasonal variation. This directly impacts your system's energy production.

This depends on local policies and grid conditions. Consider: net metering availability (varies by country), feed-in tariff rates, grid stability, battery storage costs, future energy needs (EVs, heat pumps), and utility interconnection limits. Some countries encourage oversizing for grid export, while others limit system size to historical consumption. Research local solar policies and incentives.

Solar economics improve with higher electricity rates. Typical residential rates: Germany (€0.30/kWh), Australia (A$0.25/kWh), USA (US$0.12/kWh), India (₹7.50/kWh), Pakistan (PKR 25/kWh). Countries with high electricity costs see faster payback periods. Time-of-use rates, seasonal pricing, and grid export rates also impact savings. The calculator helps estimate savings based on your local electricity rate.