You can set the currency, decimal and thousand separators in your config.yml file.
SilverShop\Extension\ShopConfigExtension:
base_currency: 'EUR'
SilverShop\ORM\FieldType\ShopCurrency:
decimal_delimiter: ','
thousand_delimiter: '.'
# european style currencies, e.g. 45,00 € instead of €45,00
append_symbol: true
See Troubleshooting for more information.