A model can also be added to the partial view :

@model Solution.Project.Namespace.MyModelClass
<p>@Model.Property</p>

In the View you can now just use:

<div>
    @Html.Partial("PartialViewExample", new MyModelClass(){Property="my property value"})  
</div>
<div>
    @{ Html.RenderPartial("PartialViewExample", new MyModelClass(){Property="my property value"}); }  
</div>

Calling the function

string InvoiceHtml = myFunction.RenderPartialViewToString("PartialInvoiceCustomer", ToInvoice); // ToInvoice is a model, you can pass parameters if needed

Function to generate HTML

public static string RenderPartialViewToString(string viewName, object model)
{
    using (var sw = new StringWriter())
    {
        BuyOnlineController controller = new BuyOnlineController(); // instance of the required controller (you can pass this as a argument if needed)

        // Create an MVC Controller Context
        var wrapper = new HttpContextWrapper(System.Web.HttpContext.Current);

        RouteData routeData = new RouteData();

        routeData.Values.Add("controller", controller.GetType().Name.ToLower().Replace("controller", ""));

        controller.ControllerContext = new ControllerContext(wrapper, routeData, controller);

        controller.ViewData.Model = model;

        var viewResult = ViewEngines.Engines.FindPartialView(controller.ControllerContext, viewName);

        var viewContext = new ViewContext(controller.ControllerContext, viewResult.View, controller.ViewData, controller.TempData, sw);
        viewResult.View.Render(viewContext, sw);

        return sw.ToString();
    }
}

Partial View - PartialInvoiceCustomer

@model eDurar.Models.BuyOnlineCartMaster
 <h2>hello customer - @Model.CartID </h2>

Html.Partial returns a string on the other hand Html.RenderPartial returns void.

Html.RenderPartial

This method returns void and the result is directly written to the HTTP response stream. That means it uses the same TextWriter object used in the current webpage/template. For this reason, this method is faster than Partial method.This method is useful when the displaying data in the partial view is already in the corresponding view model.

Example : In a blog to show comments of an article, we would like to use RenderPartial method since an article information with comments are already populated in the view model.

@{Html.RenderPartial("_Comments");}

Html.Partial

This method returns an HTML-encoded string. This can be stored in a variable. Like RenderPartial method, Partial method is also useful when the displaying data in the partial view is already in the corresponding view model.

Example: In a blog to show comments of an article, you can use Partial method since an article information with comments are already populated in the view model.

@Html.Partial("_Comments")