Brand New, purchased two decided not to use it. This is for AC HVAC compressor to reduce the LRA and allow you to use your AC with Powerwall battery backup if you are below the total current capacity or near.
You can also use it on your compatible compressor just to reduce the stress on the compressor startup.
This is compatible with most scroll compressors. In terms of your lights dimming when they first turn on it should help as it basically reduces the Locked rotor Amp of the compressor, they advertise up to 60% but its really dependent on the age of the compressor etc it could be as low as 40% but it does from an electronics perspective reduce the LRA on startup so it should help. There is no downside, even if you don't have powerwalls having a soft start on your compressor just takes the stress off the compressor and helps it last longer really.
Where you run into problems is if you are at the edge of what the current your PW(s) are producing and expect this to get you under that range, b/c you are not accounting for other loads in your home. If your AC already works with your PW and you have flickering it should help if the condition is a lack of current for those lights. If it is other issues than it won't matter. I can ship it to you today if you want just paypal me.