float to string sql cast or convert
If you directly use convert it gives you solution in terms of +e. But if we convert it to bigint first then it provide the correct conversion to string.
CONVERT(nvarchar, CAST(floattoconvert as bigint))
You can use str function but you need to be careful as it appends 0 or space while converting the same. So it would be bit tricky to use str function.