[HttpGet]
public ViewResult Index()
{
    return View(CreateExportableGrid());
}

[HttpGet]
public ViewResult ExportIndex()
{
    // Using EPPlus from nuget
    using (ExcelPackage package = new ExcelPackage())
    {
        Int32 row = 2;
        Int32 col = 1;

        package.Workbook.Worksheets.Add("Data");
        IGrid<Person> grid = CreateExportableGrid();
        ExcelWorksheet sheet = package.Workbook.Worksheets["Data"];

        foreach (IGridColumn column in grid.Columns)
        {
            sheet.Cells[1, col].Value = column.Title;
            sheet.Column(col++).Width = 18;

            column.IsEncoded = false;
        }

        foreach (IGridRow<Person> gridRow in grid.Rows)
        {
            col = 1;
            foreach (IGridColumn column in grid.Columns)
                sheet.Cells[row, col++].Value = column.ValueFor(gridRow);

            row++;
        }

        return File(package.GetAsByteArray(), "application/unknown", "Export.xlsx");
    }
}

private IGrid<Person> CreateExportableGrid()
{
    IGrid<Person> grid = new Grid<Person>(repository.GetPeople());
    grid.ViewContext = new ViewContext { HttpContext = HttpContext };
    grid.Query = Request.Query;

    grid.Columns.Add(model => model.Name).Titled("Name");
    grid.Columns.Add(model => model.Surname).Titled("Surname");

    grid.Columns.Add(model => model.Age).Titled("Age");
    grid.Columns.Add(model => model.Birthday).Titled("Birthday").Formatted("{0:d}");
    grid.Columns.Add(model => model.IsWorking).Titled("Employed");

    grid.Pager = new GridPager<Person>(grid);
    grid.Processors.Add(grid.Pager);
    grid.Pager.RowsPerPage = 6;

    foreach (IGridColumn column in grid.Columns)
    {
        column.Filter.IsEnabled = true;
        column.Sort.IsEnabled = true;
    }

    return grid;
}

@model IGrid<Person>

<a href="@(Url.Action("ExportIndex") + "?" + ViewContext.HttpContext.Request.QueryString)">Export</a>

@(new HtmlGrid<Person>(Html, Model))