The CO2 savings are calculated as the difference between the CO2 emissions in the current situation, i.e., without PV system, and in the future situation with PV system.
To calculate the current emissions, the specified annual electricity consumption (kWh) is multiplied by a country-specific factor for the CO2 emissions of 1 kWh of electricity of the average electricity mix. The country-specific CO2 emissions of 1 kWh of electricity of the average electricity mix are regularly updated by Eturnity. The source of the data can be seen on the PDF.
To calculate the emissions of the future situation (with PV system), the annual amount of electricity produced (kWh) is multiplied by a reduced factor for the CO2 emissions of 1 kWh of electricity of the average electricity mix. The country-specific factor is thereby reduced by a generic value for the assumed CO2 emissions of PV modules. The CO2 emissions of PV systems are considered over their lifetime. The value of the CO2 emissions of PV modules is regularly updated by Eturnity. The source of the information can be seen on the PDF.
The calculation of further information on CO2 emissions is based on this difference.
- The comparison with the kilometres travelled is based on average emissions of 0.2 kg CO2/km.
- The comparison with the trees assumes that a tree can absorb 12.5 kg of CO2 per year.
- The calculation of the reduction of the footprint is based on the comparison with a country-specific average CO2 emission per person per year. If the corresponding information has been entered in the project (settings), the number of residents is also considered for this calculation. By default, two persons are assumed.