The solera system

The sherry producers have a system of barrel-ageing, called the “solera” system, which is a crucial part of the production process. The solera barrels are topped-up with new wine as the mature sherry is bottled, to ensure that the wine ages evenly and that the quality of the sherry produced remains consistent. The sherry casks are kept in bodegas (barrel stores), which encourages some of the wine to evaporate and results in further fortification - some old oloroso sherries have an alcohol content of up to 24 per cent.