Detailed System LCE

In this tab you can define a detailed breakdown of the CO2 emissions associated with the different components of the PV installation. The potential sources of CO2 emissions are grouped into three categories with different sub-components.

If reliable Life Cycle Emissions figures for a component are directly available from a manufacturer or some other data source, these values should be used preferentially. If these numbers are not available, some of the components allow to estimate the LCE via the 'Grey Energy', which is the energy involved in the production of this component. In this case a conversion factor is needed to convert the grey energy into the LCE value.

The LCE values are given in kgCO2 per 'unit', the unit depending on the category and the user's choice. For each category you have to supply also the quantity. Where possible, PVsyst will insert values that are taken from the current Variant. For each category the contribution to the total CO2 amount is computed and displayed in the last column. The total value is given at the bottom of this column in tons of CO2 and will be calculated automatically as changes are made to the different fields in the tab. This value will be immediately reflected in the 'Overview' Tab.

The categories with their sub-components are described in the following

PV modules

This category is subdivided into the production of the modules themselves and the transportation to the site of the installation.

PV Modules

The PV module production is usually the most important contribution to the System LCE emissions. Values for LCE and grey energy vary in a large range. PVsyst provides default values found in publications for mono-crystalline silicon. By default PVsyst will use the estimation via grey energy, and use as default conversion factor the Emissions associated to electricity production for China, as given in the IEA list.

Transport 1 / 2

Transportation of the modules is divided into two separate contributions, to allow accounting for two different means of transportation. Usually these are ship cargo and land transportation. The load of the transport is calculated from the total weight of the PV modules defined in the project. The distances have to be supplied by the user. The default values proposed for the LCE values are 35 gCO2/t/km and 60 gCO2/t/km, which correspond to long distance ship cargo and large truck transportation respectively.

Balance of System (BoS)

This category encompasses all other components needed for the construction of the PV installation. Since these contributions are usually much smaller than the ones from the PV modules, no transportation item is foreseen in this case.

Supports/Trackers

PVsyst will estimate the amount of steel needed for the number of modules in the project. In case of a tracking project the number of trackers will be used for this. The default values for LCE and grey energy correspond to the production of 1 kg of steel. By default the estimation via grey energy is chosen. The default value for the conversion factor is the LCE associated to electricity production in the country of the project site.

Concrete

Concrete is often a non-negligible source of CO2 emissions. The default value is given for mass and trench foundations.

Inverters

Values for LCE or grey energy of inverters can vary a lot, depending on technology and manufacturer. The program proposes as default to estimate the LCE value from the grey energy. The default value is for inverters in the 2.5 kW range. The default conversion factor is for emissions associated to electricity production in the country of the project site (from the IEA list).

Cabling

The default LCE and grey energy values are taken for Copper. The program chooses by default the estimation of the LCE value from the grey energy. The default conversion factor is for emissions associated to electricity production in Chile, since this country is the world's largest producer of copper.

Additional

Maintenance

Maintenance can include regular inspections, repairs, cleaning of panels, cleaning of vegetation, etc. Since this is very specific for each project, PVsyst will not propose any default values. It is left to the user to estimate a realistic value. In general this contribution is rather small and neglecting it will have little impact on the result.

Dismantling

This item should include everything that happens at the end of the PV installation lifetime, like dismantling, recycling, disposal, land restoration, etc. Since this is rather specific to each project, the program does not propose any default values. It is left to the user to provide reasonable values here.

Other

This item can take any contribution that is not covered by the other groups and components. It is a single fixed value that is added to the total balance.

Data Sources

Detailed information on LCE values can be obtained from specialized providers, like for example ECOINVENT, Carbon Trust, International Energy Agency (IEA), Intergovernmental Panel on Climate Change (IPCC), etc. The following table contains a few figures found in recent publications (be aware, that these are estimates based on conditions and assumptions that can vary largely between countries, technologies and procedures):