The required amount of PV energy production for a net zero building is equal to the total energy consumption for the building in question, generally determined on an annual basis. The required area for the PV array depends on the location of the building (latitude), cloud cover and climate, the tilt of the PV panels (angle), the orientation of the panels, and the efficiency of the system. Depending on the size, orientation, and angle of the building's roof, the full PV array may be able to fit on it.

From the modelling performed for this guide, a near net zero, 2550 ft² (237 m²) two story house with a basement, located in Victoria (CZ4), with an enclosure-first approach, high-efficiency building equipment, and a south-facing single gable at a 6/12 slope, can produce 8.4kW (enough to power the full house) and only use 58.8% of the total roof area.

A useful online resource for calculating a PV array energy-generating capability is the PVWatts Calculator by NREL.