<div id="DivToPrint">
                            <asp:Panel runat="server" ID="PanelViewDetails" Visible="false">
                            
                            ... codice aspx con vari oggetti server side, table e quanto altro ...

                           </asp:Panel>
                            </div>
                            <asp:Button runat="server" ID="btnPrintJS" Text="PRINT DOC" OnClientClick="window.PrintPreview('DivToPrint'); return false" />