CO₂ Offset Calculator — How Much Carbon Does Solar Save?
Calculate how many tons of CO₂ your solar panels offset per year and over their lifetime. Compare to equivalent trees planted and miles not driven.
· Free · No signup required
How to use this calculator
- Enter your solar system size in kilowatts (kW). A typical US home system is 6–10 kW.
- Enter your local electricity rate — this determines the carbon intensity of the grid electricity you are offsetting.
- Adjust peak sun hours if you know your local value (use our state selector for accuracy).
- Your annual CO₂ savings, lifetime offset and equivalents appear instantly.
Understanding your results
CO₂ savings are calculated using the EPA’s average US grid emission factor of 0.386 kg CO₂ per kWh. Your solar panels displace grid electricity, so every kWh they produce avoids that much carbon from being emitted at a power plant.
Lifetime offset assumes a 25-year panel lifespan with 0.5% annual degradation. The carbon payback of manufacturing solar panels is typically 1–4 years, so the net lifetime savings are substantial.
Tree equivalent uses the EPA’s estimate that an average US tree sequesters about 48 pounds (21.8 kg) of CO₂ per year. A 7kW solar system typically offsets the equivalent of 300–500 trees planted annually.
Miles not driven uses the EPA’s average car emission factor of 404 grams CO₂ per mile for a typical US passenger vehicle.