Solar EV Offset
See how much of your EV charging a home solar system covers.
About Solar EV Offset
The EV's yearly energy demand is divided into what roof output covers and what must still come from the grid. Matching solar production to EV charging shifts the car's energy cost toward a fixed investment, cutting the variable cost of driving.
Formula
Solar EV Offset
Offset % = solar output / EV energy needed x 100
- output per kW
- Yearly kilowatt-hours generated per installed kilowatt
Worked example
With the default values below, Solar EV Offset returns EV Energy Needed of 3,429. Change any input above and every figure here is recalculated in your browser.
Inputs used
- EV miles per yearminimum 0 mi
- 12,000 mi
- EV efficiencyminimum 0.1 mi/kWh
- 3.5 mi/kWh
- Solar system sizeminimum 0 kW
- 6 kW
- Output per kWminimum 0 kWh/kW
- 1,400 kWh/kW
Results
- EV Energy Needed
- 3,429 kWh
- Solar Annual Output
- 8,400 kWh
- Solar Offset
- 245.00%
- Remaining Grid Energy
- 0 kWh
Step by step
- 1Values used
- 2Solar EV Offset
- 3EV Energy Needed= 3,429 kWh
- 4Solar Annual Output= 8,400 kWh
- 5Solar Offset= 245.00
- 6Remaining Grid Energy= 0 kWh
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax or fees or charges into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Solar EV Offset calculated?
Offset % = solar output / EV energy needed x 100 The EV's yearly energy demand is divided into what roof output covers and what must still come from the grid.
Why does Solar EV Offset matter?
Matching solar production to EV charging shifts the car's energy cost toward a fixed investment, cutting the variable cost of driving.
What values do I need to enter?
This calculator takes 4 inputs: EV miles per year, EV efficiency, Solar system size, Output per kW. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.