Yes. According to NEC Article 300.3(C) conductors can occupy the same raceway or conduit so long as they have the same insulation rating. Therefore, you may install TAP or Gateway communication wire in the same conduit as PV string homeruns if the TAP wire has the same insulation voltage rating as the homeruns- typically 600V for residential applications.
The communication/control circuits of the TAPs and Gateways associated with Tigo Optimizers and Smart Modules system fall under the following NEC Articles:
- Article 300, Wiring Methods and Materials
- Article 690, Solar PV (Photovoltaic) Systems
Supplemental, Article 690.31(B) allows conductors to occupy the PV array raceway provided they are an associated system. Since gateway communication cables are associated with the rapid shutdown capability of PV arrays using Tigo, they can share a raceway with PV wire.
The most common wire type that meets these requirements is Instrumentation Tray Cable (ITC). Ensure the nominal outside diameter is less than 0.35 inches (9 mm). The cable must have at least 4 wires to accommodate the TAP and CCA terminals.