Yet.
Experience tells me that everything will eventually turn into an ad or data collection platform.
Furthermore, even if there is indeed no nefarious intent from the third-party collecting & storing your system's telemetry, if you don't get any benefit from it, why give it to them? It's still a risk they (or a some malicious attacker, or the government) use this data in the future in a way you didn't expect.
It's not always advertisements. Sometimes, the company will hire some oxygen waster that wants to boost "engagement" in order to justify their job and salary, so now your system is using your telemetry data to find ways to waste your time (as well as track whether they've indeed managed to waste it) even though advertisements themselves aren't (yet) involved.
Not to mention, advertisements don't have to be served over the same device that collects the data. The inverter company can very well collect the data, sell it to a data broker where other ad companies will use this data.
Will it work on the micro level of an individual home? Maybe, maybe not, but the potential for that data to be used to model behavior is definitely there.
Data brokers accumulate various bits of data that are unreliable and useless on their own but in aggregate they can be used to "connect the dots". If an IP address & user agent pair or tracking cookie only lights up when the solar system detects significant power draw suggesting someone is at home, you can tie a pseudonymous IP or tracking cookie to the solar system data which presumably would include name or some other bit of identifying info.
Now repeat that with all the other information you've got and you're able to paint a very detailed profile off someone.
And again, the solar data by itself is going to be nearly useless as it is entirely a function of the irradiance on the panels, and does nothing to reveal customer behavior.