Both rooftop solar and solar farms are needed in British Columbia

Zbynek Burival/Unsplash

This article was first published on Castanet on  Jul 23, 2024.

When people picture solar energy, they have two very different images in mind.

One image is a field of solar panels, tilted to the south, stretching from horizon to horizon. The second is a house, with solar panels mounted on the roof, collecting the sun’s energy. These are two very different futures.

If you compare nothing but price per watt, large solar farms win. It comes down to economies of scale. The National Renewable Energy Laboratory in the U.S. found in the third quarter of 2023, the cost per watt of utility-scale solar was $1.16 USD per watt while rooftop solar was $2.68 USD per watt.

Rooftop solar is subtracted from the residential retail rates of electricity (in B.C. through net metering), while utility-scale solar competes at the wholesale rate. The retail rate is higher than the wholesale rate. In 2024, the retail rate for B.C. Hydro is approximately $0.11 per kilowatt hour (kWh, step one). FortisBC charges $0.14/kWh. According to the U.S. Energy Administration average wholesale prices for 2024 are forecast to be 0.07 USD/kWh or 0.10 CAD/kWh (Northwest MidColumbia Index).

Utility-scale solar has to be built where land is available. That can be a long distance from where the electricity is consumed and can require expensive infrastructure to bring the electricity to its point of use. Long distances mean larger electricity losses during transmission. An advantage to rooftop solar is that the electricity is created near where it is consumed.

Utility-scale solar can face an uphill battle from environmental groups. Issues can involve land use change, endangered species and “visual impact,” let alone NIMBY (Not In My Back Yard) and BANANA (Build Nothing Anywhere Near Anybody). Rooftop solar collection systems are installed on existing buildings. B.C. has the Solar Rights Act which guarantees homeowners can install solar on their houses, regardless of neighbors opinions or restrictive covenants. An argument can be made that rooftop solar promotes renewable energy democracy. Siddarth Joshi, a PhD student at the University of Cork, described rooftop solar as “decentralised citizen-driven uptake.”

Starting in 2020, Germany made a commitment to renewables which they supported through a generous feed-in tariff. This feed-in tariff promoted rooftop solar and it catapulted Germany to the country with the largest amount of solar per capita (since eclipsed by Australia and the Netherlands). The policy drove manufacturing and local job creation but Germany had another reason. It felt a pro-renewable energy policy should be participatory, a democracy where individual families could participate.

Another aspect, brought up by Joshua Pearce at Western University, is the environmental payback time for utility-scale and rooftop solar. When you manufacture the equipment for solar (solar panels, mounting racks, inverter, wiring) you use electricity, often electricity that does not come from clean sources. When you manufacture equipment, you also use up water. Pearce carried out an analysis comparing utility-scale and rooftop solar and found that rooftop solar had a shorter environmental payback time for two reasons. First, rooftop solar requires less mounting hardware since it is attached to the structure of your roof. Second, as mentioned above, rooftop solar produces electricity closer to the point of use, reducing transmission losses.

There are many strong arguments in favour of rooftop solar, however the weakness lies in the rooftops themselves. If every square meter of rooftop could be covered by solar panels we could produce enough electricity to meet our needs. However, some rooftops face the wrong direction or have skylights and chimneys which make them partially or wholly unsuitable for solar.

B.C. is pursuing a strong solar policy, supporting rooftop solar through net metering and bringing in more utility-scale solar through the 2024 BC Hydro power call. We are going to need them both.

 

Articles and cartoons on Teaspoon Energy by Kristy Dyer are licensed under a Creative Commons Attribution-NoDerivatives 4.0 International License You may reprint this as-is for free, contact me to request changes.