The Life Cycle Assessment
A thorough Life Cycle Assessment (LCA) of the PVACCEPT demonstration objects was carried out by the University of Siena (UNISI) team in accordance to the relevant recommendations by the International Standardisation Office (EN ISO 14040 and updates). In particular, by using their original "Sustainability Multicriteria Multiscale Assessment" (SUMMA) approach, the UNISI team employed a selection of Life Cycle Impact Assessment methods, which offer complementary points of view on the complex issue of environmental impact assessment and address many relevant impact categories. These methods are:
- Material Flow Accounting,
- Embodied Energy Analysis,
- Emergy Synthesis,
- CML 2 baseline 2000.
The analyses were first performed for the frameless crystalline-Si and CIS modules (laminates), and then extended to include the so-called Balance Of System (BOS) components for the finished demonstration objects. All direct input data were provided by the partner SMEs (Würth Solar GmbH & Co KG, Sunways AG Photovoltaic Technology, BUSI IMPIANTI S.p.A. / A.N.I.T. division), while use was made of the available LCA databases* for estimating the remaining indirect material and energy requirements.
* R. Frischknecht 1996, Ökoinventare von Energiesystemen, Eidgenössische Technische Hochschule - Energie-Stoffe-Umwelt, Zürich; Ökoinventare für Verpackungen, Schriftenreihe Umwelt Nr. 250/I, 1996, Bundesamt für Umwelt, Wald und Landschaft Bern
Summary of results
The study produced the following results:
The performance of thin-film systems (CIS technology) can
be considered quite satisfactory, especially considering their early
developmental stage, since they compare favourably to the well-
established poly-Si systems. The pivotal reason for the comparatively
low impact lies in the very small quantities of chemical compounds that
are needed in these systems, an inherent advantage of thin-film
The results for c-Si modules are strongly dependent on the assumptions
made on the purification of silicon and Si wafer manufacturing process.
Larger production runs are very likely to improve the environmental and
thermodynamic performance of PV systems; in particular, it is
reasonable to expect a fairly significant improvement in CIS modules,
given the semi-prototype nature of the systems analysed in the present
The influence of the BOS components on the finished demonstration
objects is comparatively large, especially for those modules that have
a lower intrinsic environmental impact (CIS). In any case it is worth
remembering that building-integrated PV systems can help save
considerable amounts of energy and materials when compared to
free-standing PV installations.
The overall results of the Life Cycle Energy and Environmental Impact
Assessment performed by UNISI are certainly positive. Moreover, they
are expected to further improve in the future, thanks to enlarged production
and further process- and product-related technology improvements.
This indicates a possible rosy future for architecturally-integrated
applications of advanced PV technology. A wider application of these
systems could not only spur public acceptance and awareness, but also
actively and positively contribute to the energy balance of our urban
environments with a renewable resource with low environmental and