EPBT = [E.sub.input] + [E.sub.BOS,E]/[E.sub.output], (2)
And the energy consumption of the other components, including transportation, installation, operation and maintenance, and module decommissioning or recycling, would be 2-3 orders of magnitude lower than the energy consumption of PV module manufacturing and the BOS component; thus, they could be negligible when the life cycle energy requirement is calculated in the equation of EPBT. The EPBT of the BIPV system is calculated to be 9.38 years, so during the PV module's lifetime (normally expected to be 25 years), the BIPV system could still generate a substantial amount of electricity and gain additional benefits.
As discussed above, it can be found that the energy payback time (EPBT), the environmental cost, the NPV, and so on, as well as all the performance parameters of the BIPV system are closely related to the amount of power generation.
The EPBT, environmental cost of generation, and payback period would reduce with the decrease in tilt angles, and it is beneficial for a designer to decide which angle would be chosen, according to different emphasis points.
This phase represents the crucial phase for the LCEA as given by Equation (2), where EPBT is in inverse proportion to the ([E.sub.GEN]).
Energy payback time (EPBT) and energy return on energy invested (EROI) of solar photovoltaic systems: A systematic review and meta-analysis.
However, calculating the EPBT (using Cumulative Energy Demand V1.09 method) and greenhouse gas payback time (GPBT) one-dimensional indicators  may allow some degree of comparison: for the present case of study, the EPBT was 4.7 years (above the 4.1 harmonized mean value reported in the systematic review and meta-analysis by Bhandari et al.
They reported that the EPBT of residential PV systems (no BoS) was less than 5 years in regions with low solar irradiation, such as Belgium and the UK, and about 2-3 years in regions with high irradiation (such as the south of Europe and central/south U.S.).
The former performed a study on the environmental benefits and technical impacts of installing roof-mounted BIPV systems at various locations in Malaysia and estimated that the EPBT values were 3.2-4.4 years for a 1 kWp system.
In another study on a BICPV system for Exeter, Barcelona, Madrid, Dublin, and Paris , they found that Paris, Exeter, and Dublin showed EPBT values around 45% higher than Barcelona and Madrid.