Response.Clear();

            Response.AddHeader("Content-Disposition", "attachment; filename=test.xls");
            Response.Charset = "";

            Response.ContentType = "application/ms-excel";

            StringWriter stringWriter = new StringWriter();
            HtmlTextWriter htmlWriter = new HtmlTextWriter(stringWriter);

            sourcegrid.RenderControl(htmlWriter);
            Response.Write(stringWriter.ToString());         
           
            Response.End();