Final answer:
The electrical output of a PV module is not compatible with the electric grid due to inconsistent voltage and the production of DC, requiring an inverter to convert the electricity to AC and match the grid's voltage.
Step-by-step explanation:
The electrical output of a PV module is not compatible with the electric power grid because of C) Inconsistent voltage. The power output by a solar panel fluctuates due to changes in sunlight exposure, and photovoltaic cells produce direct current (DC) rather than the alternating current (AC) utilized by the power grid. A device called an inverter is used to match the voltage and convert the DC to the necessary AC. Furthermore, PV technology can be intermittent and is not always well-matched to the energy demand, making it challenging to integrate into the electrical grid without proper storage solutions.