It's more the installation than the equipment. At least here in the states. Some equipment has some EMC compliance, some doesn't. But the install can make a dirty installation clean.
1. You get screenshots of your HF station waterfall BEFORE the installation.
2. You get IN THE CONTRACT that the noise level will not rise appreciably (half an s unit) AFTER installation.
3. You enforce this.
Twisted pair wiring will help a lot. Ferrite on the optimizers / microinverters input and output (AT THE OPTIMIZER, NOT JUST IN THE LEADS TO THE PANEL FROM THE OPTIMIZER / MICROINVERTER). Bonding wire BONDED at the panel or wall mount inverter AND at the point of exit on the roof. Ensure EVERY rail the panels mount to is bonded.
Type 31 ferrite is your friend here.
I've installed a couple hundred solar systems. Some of the residential was the dirtiest garbage I'd ever heard. After solar install, the people couldn't listen to AM Radio anymore. Then, I'd pull up to a megawatt industrial installation and be able to operate HF mobile outside the fence.
It's all in the installation. And most residential installers want to get in, get it on, and get the heck out. a 2 to 3 day turnaround was what my employer required to make money. And this was with a panel change to the house! (I can change most residential panels in about 6 hours. Power restored the same day).
The contesting.com rfi list is a great source for solar and what's going on.
For brands, Fronius, Sunny Boy (SMA) where both really noise free. APC microinverters where also really good.... And they make microinverters that will handle 4 panels with individual MPPT (meaning you have a quarter of the noise generators on the roof as if you went single optimizers or microinverters!... Other companies sell them with 2 inputs too).
Everyone's favorite, Musks Tesla, is an RFI nightmare almost all the time. I'd spend an extra 2 to 3 days twisting #10 THHN in a drill, winding every input and output to the optimizers with ferrite, ensuring every single piece of metal was bonded (which is not a requirement in all jurisdictions.).
Fronius and SMA. Those where my favorite for easy to install and really RF quiet.
--Shane
WP2ASS / ex KD6VXI