The so called "Energy pay-back time", refers to the time, measured in years, required for a complete photovoltaic system (modules, cables, electronic equipment) to compensate for the use of energy for its production.
The energy payback time depends on the amount of radiation (in the south of Europe the EPBT is lower than in areas with a lower rate of radiation), the type of system (integrated, applied, orientation and inclination of the modules) and technology (efficiency of modules and type of production process).

- EPBT for all photovoltaic systems: 3 years (on average)
- Module lifetime: 25 years (and more)
- Production of "clean" energy: 22-24 years (and more).

Energy pay-back time in relation to the photovoltaic technology, installation for an optimal orientation and inclination in Southern Europe 1700kWhm2/yr

Source: de Wild-Scholten (ECN), Sustainability: Keeping the Thin Film Industry green, 2nd EPIA International Thin Film Conference, Monaco, 2009