Determine the timezone of the SQL Server

Get SQL Server TZ

DECLARE @TimeZone VARCHAR(50)
EXEC MASTER.dbo.xp_regread 'HKEY_LOCAL_MACHINE',
'SYSTEM\CurrentControlSet\Control\TimeZoneInformation',
'TimeZoneKeyName',@TimeZone OUT
SELECT @TimeZone 

-- OR this snippet but I am not sure I trust it yet....

DECLARE @TZ SMALLINT
SELECT @TZ=DATEPART(TZ, SYSDATETIMEOFFSET())
SELECT CAST(@TZ/60 AS VARCHAR(5))+ ':' +Cast(ABS(@TZ)%60 AS VARCHAR(5));