AndNovak

Microsoft.Office.Interop.Excel.Application ExcelApp = new Microsoft.Office.Interop.Excel.Application();
ExcelApp.Application.Workbooks.Add(System.Type.Missing);
 ExcelApp.Visible = true;

                for (int i = 0; i < dataGridViewProduct.ColumnCount; i++)
                {
                    for (int j = 0; j < dataGridViewProduct.RowCount; j++)
                    {
                    if (dataGridViewProduct[i, j].Value == null)
                        ExcelApp.Cells[j + 2, i + 1] = " ";
                    else
                    {
                        ExcelApp.Cells[j + 2, i + 1] = dataGridViewProduct[i, j].Value.ToString();
                    }
                   


                    }
                }