Renders a partial template with it's model and returns the output as a string.

RenderPartialToString.cs

/// <summary>
/// Returns the rendered HTML for a partial view.
/// </summary>
/// <param name="partial">Path to partial template.</param>
/// <param name="model"></param>
/// <returns></returns>
protected string RenderPartialToString(string partial, object model)
{
    this.ViewData.Model = model;
    using (var sw = new StringWriter())
    {
        var viewResult = ViewEngines.Engines.FindPartialView(ControllerContext, partial);
        var viewContext = new ViewContext(ControllerContext, viewResult.View, ViewData, TempData, sw);
        viewResult.View.Render(viewContext, sw);
        viewResult.ViewEngine.ReleaseView(ControllerContext, viewResult.View);
        return sw.GetStringBuilder().ToString();
    }
}