PV Panel Sizing Calculator
Calculate the number of solar panels needed for your home.
(Average hours of direct sunlight per day for your location)
(Power output of a single panel under standard test conditions)
(e.g., Inverter efficiency, wiring, temperature, shading. Typically 10-20%)
Understanding PV Panel Sizing
Sizing a photovoltaic (PV) solar panel system is crucial for ensuring it meets your energy needs efficiently. This calculator helps estimate the number of solar panels required based on your energy consumption, local sunlight availability, panel specifications, and system inefficiencies.
How it Works: The Calculation
The core idea is to determine the total solar energy your system needs to generate daily to cover your consumption, accounting for losses, and then divide that by the energy output of a single panel on an average sunny day.
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Target Daily Generation (kWh): Your actual daily energy needs, adjusted for system losses.
Target Daily Generation = Daily Energy Consumption / (1 - System Losses) -
Energy Generated per Panel per Day (kWh): The average daily energy produced by a single panel. This depends on its wattage and the average peak sun hours in your location.
Energy per Panel = (Panel Wattage / 1000) * Peak Sun Hours * (1 - System Losses)(We divide panel wattage by 1000 to convert Watts to kilowatts. System losses are factored in here for simplicity in the final calculation of panels, though the primary calculation uses target generation divided by potential generation per panel.) -
Number of Panels Needed: The total daily energy required divided by the energy a single panel can provide.
Number of Panels = Daily Energy Consumption / Energy Produced Per Panel Per DaySimplified:Number of Panels = Daily Energy Consumption / ((Panel Wattage / 1000) * Peak Sun Hours)(assuming losses are accounted for in the energy consumption or target generation calculation)
The calculator uses a more direct approach:
- Calculate the total DC power required from the panels to meet daily consumption after accounting for system losses:
Required DC Power (kW) = Daily Energy Consumption (kWh) / Peak Sun Hours (h) - Determine the number of panels based on the wattage of each panel:
Number of Panels = Required DC Power (kW) * 1000 / Panel Wattage (Wp) - Finally, adjust for system losses:
Number of Panels = (Daily Energy Consumption (kWh) * 1000) / (Panel Wattage (Wp) * Peak Sun Hours (h) * (1 - System Losses/100))
Key Inputs Explained:
- Daily Energy Consumption (kWh): Review your electricity bills to find your average daily usage in kilowatt-hours.
- Peak Sun Hours per Day: This is not the total hours of daylight. It's the equivalent number of hours where solar irradiance averages 1000 W/m² (standard test conditions). This varies significantly by geographic location and season. Online resources or local installers can provide this data.
- Solar Panel Wattage (Wp): This is the power rating of a single solar panel, typically ranging from 250Wp to 450Wp or more for residential systems.
- System Losses (%): Accounts for energy lost due to factors like inverter efficiency, wiring resistance, temperature effects (panels are less efficient when hot), dust, and shading. A common range is 10% to 20%.
Use Cases:
This calculator is useful for:
- Homeowners planning to install solar panels.
- Individuals interested in understanding their potential solar system size.
- Comparing different panel wattages or system efficiencies.
Disclaimer: This calculator provides an estimate. Actual system design should be done by a qualified solar professional who can conduct a site-specific assessment.