Solardotcom
10 minutes
Solar Panel Carbon Footprint: Grams of CO2 per Kilowatt-Hour
Solar panel carbon footprint is usually given in grams of CO2e per kilowatt-hour of electricity. It is a life-cycle number. The formula is footprint = total CO2e to make, ship, install and retire the system / total kWh it makes over its life. The top part is mostly factory energy. Polysilicon refining is the biggest share, then ingots and wafers, then glass and the aluminium frame. Fluorinated gas leaks add a little. The grid that powers those factories matters a great deal. The same plant run on coal power can have several times the footprint of one run on hydro. The bottom part depends on sunshine, how slowly the panel degrades and how many years it runs. Life-cycle studies put silicon panels at roughly tens of grams per kWh. Gas power is several hundred and coal is near a thousand. So even a high-carbon panel is far cleaner than fossil power over its life. The number keeps falling as factories use less energy and cleaner power. To lower it further, buyers can ask for low-carbon polysilicon, recycled aluminium and long warranties. After this Concept you can read a panel's carbon footprint, check what it assumed about sunshine and lifetime, and compare it fairly with other power sources.