Add readout for solar temperatures?

[ministryofsillywalks]

My calenta is hooked up to a solar thermal panel and a thermal tank where the warm water is stored.
On the display of my calenta I can read the temperature of these. Is there any way to add these readings to the esp?
(disclaimer: I have no idea whats going on code wise...)
In rjblake mapping file there is a mapping for "Solar Temp A" I'm guessing that might be it. But how could I add this to the code?