Экспорт DataGridView в Excel (путем копирования - вставки)

Подключаем через AddReference "Microsoft.Office.Interop.Excel"

using Excel = Microsoft.Office.Interopt.Excel;

...

private void btnExportToExcel_Click(object sender, EventArgs e)
{
    dgv.SelectAll();
    DataObject dataObj = dgv.GetClipboardContent();

    DataObject dataObject = new DataObject();
    Encoding enc = Encoding.Unicode;
    byte[] bytes = enc.GetBytes(dataObj.GetText());
    System.IO.MemoryStream stream = new System.IO.MemoryStream(bytes);
    dataObject.SetData("UnicodeText", false, stream);
    Clipboard.SetDataObject(dataObject, true);

    Microsoft.Office.Interop.Excel.Application xlexcel;
    Microsoft.Office.Interop.Excel.Workbook xlWorkBook;
    Microsoft.Office.Interop.Excel.Worksheet xlWorkSheet;
    object misValue = System.Reflection.Missing.Value;
    xlexcel = new Excel.Application();
    xlexcel.Visible = true;
    xlWorkBook = xlexcel.Workbooks.Add(misValue);
    xlWorkSheet = (Excel.Worksheet)xlWorkBook.Worksheets.get_Item(1);
    Excel.Range CR = (Excel.Range)xlWorkSheet.Cells[1, 1];
    CR.Select();

    xlWorkSheet.PasteSpecial(CR, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, true);
}