This really has been a positive. I now use my valve radios with little to no interference. Yes this is the case its not my imagination. I have a 6.5kWh solar array which I have had for a while. I decided to add a 13kW battery because the deal was good and will save me on power charges. On a good day I use 5kWh and export 28kWh which is great but I discovered today that one of my old radios was very quite between stations, on checking I found all of them were.

I investigated this with some tech friends of mine and they all said yes if the invertors have good filters there will be very little noise and because my home isn't drawing from the grid the system basically stops all interference coming in through the grid.

There seems to be no discernable noise from the current inverter. Its predecessor failed to make it out of warranty. This system pre-dates the current batteries and should one be installed, it will likely get bunded so it can't set the farm alight. Panels are on the workshop not the house. The power feed to the house's sub board, is from the workshop distributor. The main distributor has four lines out, all underground.

The failure of the solar inverter generated some severe spikes & caused two protection devices to kill the circuits they were on. One being the TV.

The biggest killer of signal in the rural area is Wireless Internet. The workshop tends to be a bit of a Faraday Cage so the valve radios get fed by the 37m outside long wire antenna. To calibrate a radio and often service it. The Internet box is in the workshop and you have to shut it off to shut it up as its like a symphony orchestra.

There will be a benefit if you are a low user of electricity, particularly of you have a large number of solar panels however going forward.

Metal on roofing in homes and outhouses will indeed be a faraday cage from interference from lightning and interference caused by external sources but they will be giving you this benefit anyway.

That, especially the lack of mains noise because of the backfeeding, is news to me. Honestly rather exciting to hear that can be the case.
I wonder of there is a tell tale way of knowing what inverters are best suited in terms of RF interference

The big issue with the Nr 3 studio & radio workshop is that it doubles as the Farm office and there are no computers in the house. That puts all of the Wireless internet & one noisy computer in it, along with the mobile phone that struggles to get signal from anywhere. That means that the strongest fundamental signal is the noisy Wireless Internet.

Studio/ Workshop is wholly metal with spray foam insulation walls & roof. Building is separately grounded into a watercourse.