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Both calculators run independently — change the inputs on either side to compare results.
EV Home-Charging Solar Offset Calculator
Calculate how many kilowatts of extra solar capacity you need to cover your EV's home charging. Useful when sizing a rooftop solar addition for a new or existing electric vehicle.
Extra solar capacity for EV
2.77 kW
2-4 kW (about 5-10 panels) covers a typical commuter. The 2.77 kW example fully offsets 12,000 mi/yr; dropping to 50% offset would halve this to under 1.4 kW.
This is the added solar array size (kW DC) to offset your chosen share of EV charging; a typical residential panel is about 0.4 kW, so divide by ~0.4 to estimate panel count.
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.
Key differences
| EV Home-Charging Solar Offset Calculator | Solar Panel System Sizing Calculator | |
|---|---|---|
| Category | Solar Energy | Solar Energy |
| Inputs required | 6 | 5 |
| Result | Extra solar capacity for EV (kW) | Solar panels needed (panels) |
| What it does | Calculate how many kilowatts of extra solar capacity you need to cover your EV's home charging. Useful when sizing a rooftop solar addition for a new or existing electric vehicle. | 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. |