Hacker might change something that effects performance, but I don't think there is much for them to steal, which likely means not so much interest to hack it unless purely done as some sort of prank for the thrill of it. Most hackers are trying to find some sort of financial gain or something that will lead to that.
He is worried about the solar system providing some kind of backdoor to the other stuff he does with his wifi, which is probably the rest of his life. It's not an unreasonable concern, but in my experience solar companies are competent enough that it's no more worry than any other device on your network.
That's nothing to do with cell vs. Wifi.
My guess would be about 5 percent have 100% hardwire ethernet cord. But it depends a little how you consider it. Solaredge has a dedicated zigbee device that plugs into the router via ethernet, but communicates wirelessly with the inverter(s). So it's not 100% hardwire, but from the standpoint of not being on wifi (and therefore not susceptible to changing wifi passwords or SSIDs) it's the same as ethernet. It was also somewhat common in the past for installers to use EoP devices to extend ethernet connectivity, but I think that's fallen out of fashion (not very reliable).
The Envoy with my 2015 era Enphase system is hard wired. It was 10BaseT EoP until I installed a mesh with Ethernet ports.
I agree it is a reasonable concern because you're relying on the equipment manufacturer to keep their system firmware up to date. IOT devices are usually poorly implemented and rarely patched even when vulnerabilities are exposed.
If you're going to put something like solar on your WiFi the safest bet is to put it OUTSIDE the regular home network, and packet filter the crap out of it. That means a second wireless access point, with a private SSID, with a strong WPA key, and only the networking ports needed by the solar equipment allowed in and out. The reason is that many of those long-lived devices will slowly become network security risks as the devices become obsolete and the networking software stops being supported.
It's not just that they are rarely patched because the vendor is thoughtless. Think about something like a WiFi enabled LED bulb. Are you willing to rely on the vendor to keep updating the firmware for the 10-15 year life expectancy of your slick color-changing, dimmable, "scene-enabled" lightbulb?
They wound up owning the assets of a company I worked for 6 or 7 years ago. I don't think anyone has touched the gateway code I wrote.
Is necessary if you live in the boonies? If someone is going to hack you they are either going to do so through the ISP side of things or will be parked in front of your house while breaking into your wifi network.
I don't think it does in any case. Internet access is just for monitoring on most residential PV systems.
