Solar Roof Array & Battery Storage Output

Verified Mathematical Model & Formulation

Array Size (kW) = (Usable Roof Area sq ft / 17.5 sq ft per panel) × (Panel Wattage / 1000)
Daily kWh = Array Size (kW) × Peak Sun Hours × Derate Factor (0.80)
Annual kWh = Daily kWh × 365
Battery Backup Hours = (Battery Capacity kWh × Usable DoD%) / Essential Load (kW)

Determines the total solar panel capacity that fits on available unshaded roof space, projects real-world electricity generation considering inverter and thermal losses (standard 0.80 derate), and calculates battery backup autonomy.

Configurable Parameters & Standard Units

Usable Unshaded Roof Area (sq ft): (Default: 600 sq_ft)
Panel Nominal Rating (Watts): (Default: 400 w)
Daily Average Peak Sun Hours (Hours/day): (Default: 4.8 hours)
Battery Storage Capacity (kWh): (Default: 13.5 kwh)
Critical Continuous Backup Load (kW): (Default: 1.2 kw)

Standard Worked Example & Practical Verification

Scenario: An 800 sq ft unshaded roof using 400W tier-1 panels with 4.8 peak sun hours/day and a 13.5 kWh home battery during a 1.5 kW continuous backup load.

Calculated Solution

                  18.0 kW DC Array (~25,228 kWh / year) | 8.1 Hours Battery Autonomy
                

Practical Takeaway: This array generates enough energy to cover approximately 200% of an average 1,000 kWh/month home, allowing maximum net metering credits.

Frequently Asked Questions

What is a peak sun hour?

A peak sun hour is not just an hour of daylight; it represents one hour during which solar irradiance averages 1,000 watts per square meter (1 kW/m²). Most temperate regions receive between 3.5 and 5.5 peak sun hours daily.

How many solar panels fit on an average residential roof?

An average 1,500 sq ft home typically has 600 to 1,000 sq ft of viable south- or west-facing roof, which accommodates approximately 20 to 45 modern residential solar panels (8 kW to 18 kW capacity).

How long will a 10 kWh to 15 kWh battery run a home during a blackout?

If powering essential emergency circuits (refrigerator, LED lights, router, phone chargers at ~1 kW to 1.5 kW), a 13.5 kWh battery provides 8 to 12 hours of continuous power before recharging from the solar panels the next morning.