I think with SolarEdge there is also an issue that it requires a certain minimum voltage to operate the central inverter. This reduces the production during morning/evening/cloudy weather.
Yes, there should be a gateway switch with any system that is capable of islanding.
Here's production on a clear sunset and the next morning's clear dawn.
The little "whoopie" after 6pm is some trees on the horizon way across a field. There is nothing on the east horizon, so it comes up to power pretty quickly and linearly.
Something to note...cooler panels make more power. See how the clouds cause all the spikes in production? But when a cloud goes away, it makes more power than expected due to the panels having cooled of, so you get little peaks above the expected power curve.
The sunny boy is a 600v dc input inverter and requires 125v on the input to even wake up. It has three MPPT input strings, which is great... and string inverters are really simple if you have no shading and / or put all panels in one string on teh same roof face. One caveat for them is that the newest electrical code requires a remote shutdown box on the roof and I think it's about $400 extra.... still cheaper than the microinverters.
As power companies change their net metering agreement terms, batteries start to get more interesting. SMA requires you have the Sunny Island (6.8kw 220v inverter, 48v batteries). Sunny Island only puts out 220v, so you need a split phase transformer to get the 120/240 in us breaker boxes... an added expense.
The SolarEdge "StorEdge" inverter is only available as 7.2kw as of now, but it can hook to up to 20kwh of LG chem 350v batteries. So if you are considering battery backup, this might be interesting. You may want to advise your solar installer to plan the system with 7.2kw solar edge inverters.... I think you pop off the top portion of the SE inverter and install the StorEdge inverter later on....or just get the StorEdge now but don't hook it to a battery. I'm not sure if you can parallel two StorEdge inverters??????