Thanks for using GroupDoc.Viewer and posting on our forum. GroupDocs.Viewer provides a couple of ways to render the Excel worksheets.
Rendering one page per sheet - In this way, each worksheet of the Excel document is considered as a page and the API renders each worksheet as one Html/image page. This method could be more suitable in the situation when the sheets are not big enough. You can use HtmlOptions.CellsOptions.OnePagePerSheet = true for rendering one page per sheet.
Rendering multiple pages per sheet - There can be the scenario when the sheets may contain the huge number of rows. In that case, you can perform the partial rendering of the sheets and set the number of rows that will appear on each rendered Html/image page. The benefit of this feature is that you can fix the number of rows and each Html/image page will contain same number of rows. For more details on this, please visit here.
Since version 17.8.0, we have also introduced a feature of ignoring empty rows in Excel worksheets that allows you to exclude the empty rows from the rendering results. For details, please visit this documentation article.