Now that I’ve finally got a solar PV system installed, and I do indeed have it working beautifully with openHAB, I suppose I should reply to my own post to say that I have Enphase IQ7A microinverters and the associated Enphase Envoy, along with the just-updated version of the Enphase binding from @hilbrand (see post in Enphase binding thread). I used a combination of webgui configuration for the Envoy bridge, along with a .things file for the inverters, and then a whole lot of items and persistence rules, but there is now a huge amount of data in near-real-time coming from the Envoy and every attached microinverter.
The Enphase solution is probably overengineered for anyone who doesn’t have such problems with shading on their available roof area (at this time of year, production on the west side of our roof goes up on a cloudy day), but at least one up-side of spending all that money on a system which handles the shading well is some really comprehensive data.