Accordion widget can store the model value in the browser cookies and on every time after initial rendering, the control get the model from the cookie only. Using EnablePersistence property you can store the model value in cookies. Thus when any changes are made dynamically then those values are updated in cookie. On refreshing the page the past state of the Accordion control is maintained in cookie and control is rendered from it.
Configure state persistence of Accordion panel
The following code explains to enable state maintenance for Accordion.
Output after page refresh maintaining the previous state of Accordion widget is as follows.
Accordion Selected Item changed
Accordion state persisted after page refresh