Update capacity methods to use the new capacity API endpoints

[JamieTaylor-TUOS]

We're making a small change to the PV_Live API which affects the /capacity endpoint.

As of now, this endpoint on the "on-prem" PV_Live API returns a directory listing, with folders for each PV capacity update which contain a series of compressed files, see e.g. https://api.solar.sheffield.ac.uk/capacity/.

Note that the "GCP-hosted" PV_Live API is currently configured to redirect requests for https://api.pvlive.uk/capacity/ to https://api.solar.sheffield.ac.uk/capacity/.

We have now developed a new API endpoint to provision capacity data, which is more aligned with the other PV_Live API endpoints in that it provides a JSON response. The new capacity data endpoint is currently available for testing at https://api.solar.sheffield.ac.uk/capacity2/

After sunset on Monday 7th July 2025, we plan to:
decommission the old endpoint: https://api.solar.sheffield.ac.uk/capacity/
rename the /capacity2 endpoint:
from https://api.solar.sheffield.ac.uk/capacity2/
to: https://api.solar.sheffield.ac.uk/capacity/
remove the redirect from api.pvlive.uk/capacity/ to api.solar.sheffield.ac.uk/capacity/
The capacity data will instead be hosted natively on GCP
We recommend using https://api.solar.sheffield.ac.uk/capacity to access capacity data going forward
The on-prem API (https://api.solar.sheffield.ac.uk/) remains as a test environment

[JulianBriggs]

Done
Endpoint /capacity
now now returns data in "new" format.

[JamieTaylor-TUOS]

Done Endpoint /capacity now now returns data in "new" format.

@JulianBriggs I think you closed the wrong issue - this one relates to updates needed in the PV_Live-API Python package in order to reflect the changes made to the API (am working on it now)

[AndrewCRichards]

I notice that the API capacity page has a Capacity Data link currently pointing to an on-prem endpoint, but I think this should be updated to the corresponding cloud endpoint (?) (this is in ssapi app/templates/pv/capacity.html)

(also to note that the description of this Github issue says "We recommend using https://api.solar.sheffield.ac.uk/capacity to access capacity data going forward" which should presumably be https://api.pvlive.uk/capacity )

[JamieTaylor-TUOS]

@AndrewCRichards I think you might've re-opened to wrong issue...

(also to note that the description of this Github issue says "We recommend using https://api.solar.sheffield.ac.uk/capacity to access capacity data going forward" which should presumably be https://api.pvlive.uk/capacity )

The Issue description above is an extract from an email sent by Julian, so presumably this was a typo in the email - it hasn't affected the PR that resulted from this Issue.

I notice that the API capacity page has a Capacity Data link currently pointing to an on-prem endpoint, but I think this should be updated to the corresponding cloud endpoint (?) (this is in ssapi app/templates/pv/capacity.html)

This seems like an issue that belongs on https://github.com/SheffieldSolar/ssapi - please create a new issue there to correct the link