Each Eurocode part has a corresponding UK National Annex (NA) that specifies the nationally determined parameters (NDPs) applicable to UK practice. These include partial safety factors, load combination coefficients, and design values that differ from Eurocode recommended values. Using the correct UK NA values is essential for structurally valid assessments of UK buildings.
For solar PV structural work, key UK National Annexes include those for EN 1991-1-4 (wind loads, which contains the UK basic wind velocity map) and EN 1991-1-3 (snow loads, with the UK ground snow load map). All Solar Surveys calculations reference the current published UK NAs for each relevant Eurocode part.