I'm also an Enphase home solar user. I got an email shortly after installation that if I went a month without checking the app for my panels, I'd void my warrantee. This strikes me as a cheap way to get out of your obligations to a customer who's paid >$20,000 for the panels and associated installation.
The stated reason is that homeowners need to check the app to make sure there aren't any emergencies that need to be dealt with. But couldn't you check that yourself via the hardware that sends data to the app? And if that data gets cut off due to a hardware problem, couldn't you notify the owner via another channel -- like the email address you used to let me know about his policy after I've already purchased the system?