Avoided Carbon Dioxide Emissions

Assuming that average emission of fossil fuel electricity is displaced by the AC electricity produced, each kWp of solar electricity system avoids the following greenhouse gas emissions per year:

• roof 0.5 - 1.2 tonnes CO2 equivalent / kWp / year
• facade 0.4 - 0.8 tonnes CO2 equivalent / kWp / year

The term ‘tonnes CO2 equivalent’ allows for accepted avoidance of other greenhouse gases. If the solar electricity displaces 'average generation mix' electricity instead of fossil fuel-generated electricity, the above figures are reduced by approximately 30%.

Carbon dioxide payback time
The number of years of operation to avoid more greenhouse gas emissions than arise in the manufacture of the complete system (modules, mountings, cables, inverter).

This assumes that average emission fossil fuel electricity is displaced by the AC electricity produced. If the solar electricity displaces 'average generation mix' electricity instead of fossil fuel-generated electricity, the CO2 payback times increase by approximately 30%. This includes accepted allowance for avoided building materials.

• roof 3.3 - 7.1 years
• facade 5.1 - 9.8 years

The above are for systems using modules made from silicon cells where all the silicon purification and processing are carried out using hydroelectricity. This applies to some of our modules. For systems using modules made from silicon cells where the silicon purification and processing are not carried out using hydroelectricity, the energy payback times are:

• roof 1.5 - 3.1 years
• facade 2.3 - 4.3 years