It will be interesting to see if you can find TC-ER without the EGC...
Where is TC-ER cable permitted for PV?
The new 336.6 requires associated fittings to be listed.
In the 2014 NEC this was added to 690.31:
(D) Multiconductor Cable. Multiconductor cable Type
TC-ER or Type USE-2 shall be permitted in outdoor locations
in PV inverter output circuits where used with utility-interactive
inverters mounted in locations that are not
readily accessible. The cable shall be secured at intervals
not exceeding 1.8 m (6 ft). Equipment grounding for the
utilization equipment shall be provided by an equipment
grounding conductor within the cable.
In 2017 that was changed to:
Multiconductor Cable. Jacketed multiconductor cable
assemblies listed and identified for the application shall be
permitted in outdoor locations. The cable shall be secured at
intervals not exceeding 1.8 m (6 ft).
So the 2014 NEC specifically allows TC-ER limited use and 2017 if it is identified for the application. There is also article 336 which puts a lot of limits on TC use. Before 2014 690 did not specifically address multi-conductor cable and I don't know if anyone was trying to use TC.
There was a problem with people wanting to use non-TC in trays in the PV array and 690.31(C)(2) was added in 2014 to allow the use of PV Wire in cable trays.
What's the driver for wanting to use TC anyway? Just cost or are their other advantages?