Sorry for the late reply. The notifications go to my junk folder…
I haven’t tried but from the link posted by bankstownbloke, if you donate $15 to pvoutput.org, you have access specifying a siteID of any system in a GET request to the server and you can access data that is archived (older than 6 months). After making the donation, it seems that entering the following URL in your browser would return the detailed 5-minute data for an entire day
https://pvoutput.org/service/r2/getstatus.jsp?sid=“any system id”&key=“your API key”&h=1&d=“YYYYMMDD”
Replace the contents in-between the double-quotes with the actual value and remove the quotes too.
With some programming skills, you can automate those requests to get this data for an entire year without entering 365 times that URL with a different date.
Hope that helps.