I just spent a few minutes going through their web site and am a bit confused on how it all goes together.
The basic rapid shutdown is straightforward.
View attachment 114160
You can find this diagram and more info here:
https://www.fonrich.com/PV-RSD-Main-Controller-pd45186452.html
If the monitor & Gateway gets a shutdown, it sends a signal to the head module which converts it to a DC Power Line Control signal to the Tail modules. When the tail modules detect the signal, they open the PV line.
However, I don't yet see how the Arc Fault protection is integrated with the Rapid Shutdown.
They have a few Arc Fault products.
1)
A stand-alone detector that has an alarm out and Modbus communication but is *only* a detector. I am not sure if this can be integrated with the Rapid Shutdown system. (Can the alarm out be wired to the monitor & Gateway to trigger a rapid shutdown? Does the Monitor & Gateway provide the power the Arc Fault detector needs?)
2)
An integrated stand-alone box that contains the detector and a set of relays that will disconnect the PV strings when an arc is detected. This product seems to be completely independent of the rapid shutdown system.
3)
A DC monitor system that can detect arc faults and DC leakage (Ground Faults) but it looks like there are a lot of different components are needed to put it all together. It is also not clear how/if it would integrate with the rapid shut-down system.
Overall, it looks like they have some interesting solutions but implementing Ground Fault, Arc Fault and Rapid shutdown is going to require a lot of gear. I could not find pricing but it looks like this is targeted at commercial solar plants so it is likely to be quite pricy. I suspect that by the time you spend the money on this, you would find it cheaper and easier to buy an inverter that supports the functions more directly.
The good news is that the question posed in the original post of this thread has been answered: Yes! There is at least one stand-alone Arc Fault protection product on the market.
I will watch this thread with the hopes of learning more.