Small-scale solar best for environment but agrivoltaics may be the answer


study conducted at the University of Western Ontario compared both large and small solar installations and concluded that small-scale solar systems are better for the environment than even the largest, most efficient, utility-scale solar project.

Solar is scaling up in both the U.S. and Canada in part because Today solar energy is the lowest cost form of new-build electricity in  many markets, according to a the energy and resources report by Ernst & Young, which notes that the global weighted average levelized cost of electricity (LCOE) for solar is 29% lower than the cheapest fossil fuel alternative.

To eliminate carbon emissions and meet U.S. and Canada’s clean energy goals, many more solar panels must be installed. A study that looked at the agrivoltaic potential in Canada predicted we would need only 1% of Canada’s agricultural land to offset all fossil fuels for electricity generation if we installed large-scale solar farms. While this is a modest amount of land, the researchers at University of Western Ontario questioned whether it is better for the environment to have a few large-scale solar farms or many smaller rooftop systems.

The lifecycle analysis study conducted by Riya Roy and Joshua M. Pearce compared rooftop solar systems to multi-megawatt utility-scale solar PV systems from production to decommission. They found rooftop solar systems require 21% to 54% less input energy, make 18% to 59% less carbon dioxide equivalent of greenhouse gas emissions, and consume a reduced quantity of water ranging from 1% to 12% per kilowatt-peak.



Thus the researchers calculated energy payback time of rooftop solar systems is approximately 51% to 57% lower than that of ground-mounted solar systems across all locations, with the main reason being that rooftop systems don’t required the racking or trackers used in large-scale projects. Plus they are usually closer to transmission lines, whereas many utility-scale installations need lines added or they must account for transmission losses if running a long distance.

Source: Joshua M. Pearce

The researchers determined that the carbon dioxide payback time was 378% to 428% longer for ground mount large-scale solar installations, compared to rooftop solar for the same modules.

The reality

While the research shows that small, rooftop installations are better for the environment, the researchers concluded that a mix of both is needed because there are not enough rooftops to meet electrification needs, if we take into account heating and transportation. Agrivoltaics, which is dual-use, offers advantages because it uses land for both energy generation as well as food production, according to the authors of the study.


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