Permanently dispelling a myth of photovoltaics via the adoption of a new net energy indicator

For many years, the photovoltaics (PV) community has relied on the concept of energy payback time (EPT) as a means of quantifying the ratio of energy generated from a PV panel or system over its lifetime, compared to the energy that was required to fabricate it. Few other energy technologies are so judged and this paper argues that the EPT concept is obsolete, misleading and may possibly even contribute to keeping the myth alive, that ‘That PV does not payback the energy used to create it’. Therefore, a new norm for the PV community is proposed, the energy yield ratio (EYR), as used by Gürzenich et al. (Int J Life Cycle Assess 1999; 4(3): 144–9). EYR values for three different PV products (a single multicrystalline silicon module, 2 kW rooftop grid-connected system, and a solar home system) are determined to be 4.8–13.9, many times the energy inputs required to fabricate the system. r 2006 Elsevier Ltd. All rights reserved.