This is a problem many people have. In the german language the decimal separator is a comma too. When having the english database system all decimal separators are returned with a dot.

When switching the local country settings the decimal separator is changed in management studio but also in excel. And, by the way, in ALL other programs what you don't want.

What is needed is a configuration for the decimal separator for the management studio only. So one could change the output to get the comma as decimal separator and copy it to excel without having problems. But this configuration is still not existing.