Solar Generation Estimator

Solar Panel Daily Output Calculator (Wh / kWh per day)

Calculating how many solar panels are needed to run specific appliances daily. Estimates daily and monthly kilowatt-hours generated based on solar panel wattage, regional peak sun hours, and real-world system losses.

⚡ Solar Panel Daily Output Calculator (Wh / kWh per day)
Watts
Hours/Day
Calculated Result
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Instant Calculation
Auxiliary Value
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Engineering Output
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Step-by-Step Derivation ▼ Show Steps
Governing Formula Verified Physics
Daily Wh = Panel Watts × Quantity × Peak Sun Hours × 0.78 (Derating)

Calculations adhere to standard electrical equations and National Electrical Code guidelines.

Engineering Principles & Calculations

This calculator uses the exact mathematical relationships between Panel Wattage (W), Quantity of Panels, Peak Sun Hours per Day (3-6 hrs), Tilt/Efficiency Factor to determine Daily Wh, Monthly kWh, Daily Amp-hours at 12V/24V/48V. In practical applications, electrical systems must account for safety derating factors, nominal vs actual voltages, and conductor resistance losses.

Estimates daily and monthly kilowatt-hours generated based on solar panel wattage, regional peak sun hours, and real-world system losses.

Typical Application & Best Practices

Calculating how many solar panels are needed to run specific appliances daily.

Reference Matrix

Solar Panel Daily Output Calculator (Wh / kWh per day) Benchmark Lookup Table

Solar Array3.5 Peak Sun Hours4.5 Peak Sun Hours5.5 Peak Sun Hours
100 Watt Panel273 Wh/day351 Wh/day429 Wh/day
400 Watt Array1.09 kWh/day1.40 kWh/day1.72 kWh/day
800 Watt Array2.18 kWh/day2.81 kWh/day3.43 kWh/day
1,200 Watt Array3.28 kWh/day4.21 kWh/day5.15 kWh/day
3,000 Watt Array8.19 kWh/day10.53 kWh/day12.87 kWh/day
FAQ

Frequently Asked Questions

What is a Peak Sun Hour (PSH)? +
One Peak Sun Hour is defined as one hour of sunlight at an irradiance intensity of 1,000 Watts per square meter (1 kW/m²). Most US regions receive between 3.5 and 5.5 PSH daily on average.
Why is there a 78% derate factor in solar output? +
Real-world solar systems experience losses from cell heating (temperatures above 25°C reduce efficiency), wire resistance, dust/soiling, and inverter conversion losses.
How many solar panels do I need to run a refrigerator? +
A typical efficient residential refrigerator uses ~1,200 to 1,500 Wh/day. In a 4.5 PSH region, you need roughly 400 to 500 Watts of solar panels.

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