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Both calculators run independently — change the inputs on either side to compare results.
Solar Panel System Sizing Calculator
Calculate exactly how many solar panels your home needs based on your electricity bill, local sun exposure, panel wattage, and desired offset. Ideal for homeowners planning a rooftop PV installation.
Solar panels needed
21 panels
9.33: 7-10 W per monthly kWh is the normal range for a 100% offset at 4.5-5.5 sun hours. The example (9.3 W/kWh: 21x400W panels for 900 kWh) sits here.
This is installed watts per kWh of monthly usage; the formula's own math ties panel count to your offset target, sun hours, and losses, with ~7-13 W per monthly kWh being typical.
Solar Panel Output Calculator
Calculate the daily energy output (kWh) of a solar panel from its rated wattage, daily peak-sun hours, and efficiency. Use it during system sizing or to estimate production from a specific panel under your local sunlight conditions.
Key differences
| Solar Panel System Sizing Calculator | Solar Panel Output Calculator | |
|---|---|---|
| Category | Solar Energy | Solar Energy |
| Inputs required | 5 | 3 |
| Result | Solar panels needed (panels) | Daily Energy Output (kWh) |
| What it does | Calculate exactly how many solar panels your home needs based on your electricity bill, local sun exposure, panel wattage, and desired offset. Ideal for homeowners planning a rooftop PV installation. | Calculate the daily energy output (kWh) of a solar panel from its rated wattage, daily peak-sun hours, and efficiency. Use it during system sizing or to estimate production from a specific panel under your local sunlight conditions. |