If you make it to your ROI and you lose that inverter, ( I work with Inverters , actually Variable Frequency Drives and 15 years is pushing it) then you get to dive right back into that ROI because it's been extended. Its the second most expensive component in the rig. If your panels become damaged or shorted, that's the most expensive component you own and it's up to you to refinance another one.
I'm not opposed totally to solar and I love the tech. But the push from the Govt to get people into a very expensive system isn't based on it's practicality or durability.
As a electrical engineer he may have knowledge but the Electrical engineers I've run into in my past 30 years of electronic troubleshooting and industrial controls and power analysis were not competent as installers. Maybe he's the exception.