From HeatSpring Advanced PV Online Course Discussion Board
For the 705.12(D)(2)(1)(b) solution where the AHJ insists that the OCPD be placed at the current source, what does the OCPD setup look like? A small load center with a PV Breaker and a couple Ilsco taps?
There are a number of ways this can look and since this is relatively new, there is not a standard.
Overview: 705.12(D)(2)(1)(b) gives us a way of connecting to a feeder and protecting the feeder with an overcurrent protection device.
There are some who say that the overcurrent protection has to be at the source of the currents, which means that the overcurrent protection device needs to be on the load side of the inverter on the feeder it is protecting right by the inverter connection point. The reason we need to have overcurrent protection here is if the inverter current plus the current of the source overcurrent protection device feeding the feeder exceeds the ampacity of the feeder on the load side of the connection point, then we could have an overcurrent situation due to the new source of currents from the inverter going towards the loads.
Other experts say that the overcurrent protection does not have to be at the connection point and can be at the other end of the feeder before the loads, so it could be a breaker at a subpanel on the end of the feeder. Both ways would protect the feeder, but the overcurrent protection at the source would protect better and protect against short circuits of the feeder.
Answering your question:
There are different ways one could install and overcurrent protection device there at the feeder and you have stated a good way of doing that by installing a box with some taps to break apart the connection point and install the small load center. Depending on the size of the feeder, you could also Polaris connectors, a fused disconnect or a pull out fuse holder. I saw big vacuum switchgear today at a 15MW solar farm in the Philippines, which could do the job in some cases. Probably overkill for a 100A feeder going to your garage.
You can see why people would rather rely on a breaker at the subpanel.