Any experience with extreme power line networking?

They usually work very well.

Get the highest speed ones you can find, with gigabit ethernet ports.

The actual connection speed depends on signal strength, so if you are only getting 30% speed due to the distance, 30% or 1200Mbit is rather better than 30% of 200Mbit.

Circuit breakers should have little effect but any "mains suppressors" or filtered outlets / cables may kill the signal.

Things that just have lightning or "spike" suppression should have no effect but any capacitive noise filter will drastically weaken it.

Laying an Ethernet cable is actually the best solution, if that is possible.

Ethernet is specified to perform at the rated speed of the connected ports (eg. gigabit) over at least 100m, which is way more than your 150ft path.

You can add an ethernet switch in the building to distribute it to however many computer etc. you need, plus a WiFi access point (_not_ router) to give WiFi in that area.

If you set that with exactly the same name & password as the existing setup but on a different channel (out of 1, 6 & 11) any WiFi gear will "roam" between the two, using whichever is strongest.

The same setup would work via the powerline link, though possibly with limited speeds.

I have my doubts it will work. Too many panels. Ethernet over powerline is conducted by the wires, and panels and breakers cause the signal to "not" pass thru wires, but general distribution panels. That will weaken any signal. Also, the distances are rather limited as well, even over good wiring. Going 200ft via house wiring may attenuate the signal significantly (then add on the problem of the extra panels). Finally, the signal should be on the same "phase" (same side of the 120/240 circuit). Going through breakers makes it hard to ensure the signal is on the same side as the next breaker (feeding towards the next location).

Thus, I would say not likely. If you want a reliable signal, either use fiber optic cable (Ethernet to fiber converters) or a wireless bridge. There are semi-commercial wireless bridges, with external dishes/antennas, that can provide 100Mbps across several hundred feet with clear line of sight. Even in my case, I have a simple wireless bridge running up to 72Mbps about 400ft through a few trees with no problems. Get someone who knows how to set up a wireless bridge to help you... Wireless bridges cost about $100 for each end, better ones $150 (but $100 bridges should work ok).

HI Forget it this system is just so useless a wifi with an external antenna would be the best idea so it needs both antennas pointing at each other ti work either 2.4ghz or 5.2 ghz.

Used Ethernet over AC before, but at a home setting so I have doubt in your wiring, so many panels it may degrade too much. Wi-Fi extender would be a better idea. In my trial Ethernet over AC it even degraded below current Wi-Fi 802.11n speed.