The CEA has developed EcoSPV, an original impact analysis tool dedicated to photovoltaic solar power plants. With EcoPV for panels, and EcoSS for battery storage, this tool increases the eco-design potential of the French and European solar industry.
EcoSPV, a new tool dedicated to life-cycle analysis of photovoltaic power plants
Knowing the environmental impact of photovoltaic technologies enables us to work on reducing it more effectively. A great deal of research effort has gone into characterizing this impact, notably through Life Cycle Assessment (LCA). For several years now, the CEA has been developing environmental impact analysis tools, including EcoPV, an assessment and improvement tool dedicated to the eco-design of photovoltaic panels, and EcoSS, a similar tool dedicated to the environmental performance of battery storage systems. This is a major focus of the ITE INES.2S, serving the solar industry.
The impact of a photovoltaic power plant is the sum of the impact of the modules (or panels) - which is the main source of carbon or ozone impact - and the impact of what is called "BOS" (for Balance of System). The BOS is made up of all the components of a photovoltaic power plant or system, other than the photovoltaic panels: cabling, switches, a mounting system, inverter(s), storage, etc.
The significant contribution of BOS to certain environmental impacts, such as those linked to ecotoxicity or human toxicity (with a share of over 75% of this criterion), makes the study of this area particularly important. This is especially true given that the impact of photovoltaic panels is decreasing over the years, with the result that the proportion of environmental impact due to BOS in power plants is increasing.
The problem is that the data used in the literature to characterize the impact of BOS are in most cases outdated. This has a direct impact on the quality and relevance of LCA results. In 2020, for example, we can find data dating from 2000-2004, largely technologically outdated, in LCA recommendations from official and renowned players. The scarcity and irrelevance of these data can be explained, for illustration, by the lack of availability of inverter manufacturers to provide inventories of materials/processes enabling characterization of the impact of their products. In this highly competitive field, disclosing the composition of a product would have negative consequences for them.
In this context, CEA has developed its first impact analysis tool dedicated to power plants, coupled with a database incorporating up-to-date data. The aim is to provide more accurate, consistent and customized impact results, with little or no need for expert time.
EcoSPV, an easy-to-use, interactive tool
In its first version, the EcoSPV tool takes into account the main components of an electrical installation: inverters (to convert the direct current electricity produced into alternating current), transformers (to raise the voltage of the electricity to match that of the grid), photovoltaic modules and their supports, and electrical cables. These are the components presumed to have the greatest environmental impact (see box: EcoSPV tool frontiers).
The tool's integrated impact database is based as far as possible on primary data, obtained from drawings or manufacturers' information.
EcoSPV integrates an easy-to-use, interactive interface for easy parameter setting of the various components (inverters/transformers, cables, modules and module supports), and information concerning the power plant (location, installed power).
The proposed approach is to systematically model two plants in parallel: the plant under study and a "reference" plant, which can be modified as required. By default, the reference plant incorporates "classic" values resulting from the modeling of a real case, which can be referred to in case of doubt.
When customized, it enables comparative analysis. It is possible, for instance, to model exactly the same two power plants, with only one difference, to measure the impact of this choice.
The tool produces various indicators, such as the energy and CO2 payback times, and provides an overall graph with the impacts in proportion for the various components, with the option of "zooming in" on a particular impact. Each component is treated in the same detail, enabling impacts to be attributed more precisely to sub-components.
EcoSPV completes the set of tools dedicated to life cycle analysis and essential to eco-design, developed within the framework of the INES.2S ITE. Our researchers will be continuing their work to extend the limits taken into account by the tool to other components, other types of power plant, and to add other life-cycle stages (recycling, transport, end-of-life).
ECOSPV TOOL FRONTIERS
The current tool TAKES INTO ACCOUNT the main components of the electrical installation: inverters (whose function is to convert the DC electricity coming out of the solar modules into AC), transformers (which raise the voltage of the electricity to match that of the grid), photovoltaic modules and their supports, and electrical cables. These are the components presumed to have the greatest environmental impact.
EXCLUDED at this stage are : the digging of cable trenches, junction boxes and additional protection for underground cables, cables linking inverters to transformers, electrical boxes integrated into electrical substations, all ancillary installations, such as the premises required for employees, SCADA (monitoring), video surveillance, the structural work, i.e. the preparation of the land beforehand (clearing, servicing, earthworks), the fencing surrounding the power plant.
Furthermore, not all phases of the life cycle are taken into account. Only the extraction, manufacturing and installation phases are currently included in the scope of this study.