datagridview export to excel

Try CSV export

private void ToCsV(DataGridView dGV, string filename)
    {
        string separator = ",";
        StringBuilder stOutput = new StringBuilder();
        // Export titles: 
        StringBuilder sHeaders = new StringBuilder();
        for (int j = 0; j < dGV.Columns.Count; j++)
        {
            sHeaders.Append(dGV.Columns[j].HeaderText);
            sHeaders.Append(separator);
        }
        stOutput.AppendLine(sHeaders.ToString());
        // Export data. 
        for (int i = 0; i < dGV.RowCount - 1; i++)
        {
            StringBuilder stLine = new StringBuilder();
            for (int j = 0; j < dGV.ColumnCount; j++)
            {
                stLine.Append(Convert.ToString(dGV[j, i].Value));
                stLine.Append(separator);
            }
            stOutput.AppendLine(stLine.ToString());
        }

        File.WriteAllText(filename, stOutput.ToString());
    }