@(Html.Telerik().Grid(Model)
    .Name("Grid")
            .ToolBar(commands => commands
                .Custom()
                    .HtmlAttributes(new { id = "export" })
                    .Text("Export to Excel")
                    .Action("ExportExcel", "Grid", new { page = 1, orderBy = "~", filter = "~" }))

        .DataKeys(keys =>
        {
            keys.Add(Id => Id.Itemid);
        })

public ActionResult ExportExcel(int page, string orderBy, string filter)
    {
        IEnumerable orders = GetItems().AsQueryable().ToGridModel(page, int.MaxValue, orderBy, string.Empty, filter).Data;