Fig. 5: Solar photovoltaic (PV) system ground-mounted area needed to achieve 100% on-site renewable energy production as a multiple of controlled environment agriculture (CEA) facility footprint.

Each data point indicates a case in the meta-analysis for which the metric can be calculated (N = 330). A value of 1 indicates that the required solar array would effectively double the operation’s land use. Sites achieving low values tend to be greenhouses using only daylight, with energy use limited to ventilation and irrigation and perhaps other minor loads. However, since greenhouse structures require translucent roofs, those arrays are assumed to be fully ground-based. Facilities with no exact location or non-electric (or unknown) energy types are excluded. Only the all-electric subset of the sample is shown, with the exception of US and Canadian cannabis sites to define the upper boundary of potential electricity demand, for which existing fuel-based heating (80% efficiency) is modeled as converted to electric heat pumps (COP 3.5). Even without area constraints, on-site applications in lower latitudes would typically require grid interties or short-term diurnal storage, and backup power that may have associated carbon emissions would be needed at higher latitudes with seasonal darkness. Existing facilities using a mix of fuels would need to first invest in costly equipment change-outs that would enable conversion to 100% electricity.