The present invention provides for a modular, plug-and-play DCAC compatible solar photovoltaic power system and mounting frames therefor, having inexpensive modular designs which require no or minimal penetration for rooftop installation and provide enhanced wind-induced position disruption protection. For example, the stab housing may have reduced stab-openings at the power bus interface to diminish the potential of an arc flash from reaching the power buses. The system includes a means for receiving a current voice packet in the unsolicited grant service flow at the cable modem termination system from the data provider, where the current voice packet comprises a unsolicited grant service extended header. The packets include order sensitive packets and non-order sensitive packets. Diagnosis is performed in accordance with whether or not a signal based on turning on and off of the switching circuit changes normally.