The study finds that climate change will increase the value of solar panels on residential rooftops across the United States

Climate change will increase the future value of residential rooftop solar panels across the United States by up to 19% by the end of the century, according to a new study led by the University of Michigan.

The study defines the value of solar, or VOS, as the household-level financial benefits from electricity bill savings plus revenue from selling excess electricity to the grid — minus the initial installation costs.

For many American households, the total incremental profits from residential rooftop solar could reach hundreds of dollars a year by the end of the century, say the authors of the study, which is scheduled to be published April 19 in the journal Nature Climate Change.

“Given the average lifespan of 25 years for a rooftop solar installation, a system built today would roughly experience the weather of 2050,” said study senior author Michael Craig, assistant professor of energy systems in the UM School of Environment, Sustainability, Industry and Operations. Engineering in the UM College of Engineering.

“So, it’s important for households to consider future value when building solar. If households do so, our findings suggest they will see greater value from solar, and may decide to build more.”

The study shows that public awareness of the increasing future value of rooftop solar could spur increased adoption of this technology, which could in turn accelerate efforts to decarbonize the power generation system in the United States and globally.

The financial gains projected in the study were largely driven by increased demand for residential air conditioning as the climate warms. Another major factor affecting the value of rooftop PV systems is the future performance of solar panels in response to climate change, researchers say.

Craig and his colleagues analyzed data from 2,000 households in 17 US cities and estimated air conditioning demand and solar panel performance under future climates using a moderate climate warming scenario called RCP-4.5.

Rooftop solar panels have risen in value in almost all cities, in both warm and cool locations. Miami saw the largest increase in value, while only Minneapolis saw a decrease in the financial benefits of rooftop solar for households.

“This is the first study to quantify the value of rooftop solar under climate change, and we show that households across the United States will achieve greater cost savings from rooftop solar under future weather than under historical weather,” said study lead author Mai Shi. , a former visiting doctoral student at Tsinghua University in Beijing.

As demand for home cooling rises, a greater proportion of the electricity generated from solar energy will be used to cool the home, rather than being sold to the electrical grid, benefiting owners of rooftop solar systems, according to the study.

This is because the solar energy used in many states to power a home reduces the homeowner’s electricity bill through the full retail cost of electricity, while the electricity sent to the grid is added at a lower rate.

“Increased demand for cooling means more solar energy is consumed at home rather than being returned to the grid,” Craig said. “In general, it is beneficial for the owner of rooftop photovoltaics to consume the energy generated by the photovoltaic panels, rather than exporting it to the grid.”

Under the moderate climate scenario RCP-4.5, demand for residential space cooling is expected to increase in all 17 cities studied. Researchers say demand for cooling will increase by an average of 35% by mid-century and by an average of 64% by the end of the century, in all households in all cities.

Another major factor affecting the future value of residential rooftop photovoltaics is the performance of solar panels in response to rising air temperatures and changes in cloud cover.

Solar panels work best in cool and sunny weather. As air temperature or cloud cover increases, the amount of electricity generated by solar panels decreases. The study found that future performance of solar panels will vary from place to place across the United States, depending on weather conditions.

In cities like Ann Arbor, Austin, Chicago, Dallas, Detroit, Houston, Louisville and Milwaukee, higher air temperatures will reduce the efficiency of solar panels, but lower cloud cover will likely increase the amount of sunlight reaching the panels on average. The two factors are “opposable but almost identical,” the researchers say, meaning they cancel each other out.

But cities like Baltimore, Boston, Los Angeles, Minneapolis, New York City and Phoenix are expected to be warmer and cloudier in response to climate change, which will “significantly reduce” electrical energy production from rooftop solar.

However, increased cooling demand in all 17 cities is likely to outpace changes in electric panel production, resulting in financial gains for rooftop solar owners in almost every case, according to the study. Minneapolis, where limited increases in future cooling demand will combine with declining electricity production from rooftop solar panels, is an exception.

While the future financial gains from rooftop solar will be reaped mainly by households who can afford to install panels, various programs are in place to increase access, so that more people share in the expected benefits, Craig says.

For example, there are programs that cover the costs of solar energy, opening it up to low-income individuals. Governments can also install rooftop solar on public buildings, such as subsidized housing, to cover capital costs while providing the benefits of solar energy to tenants. Community solar programs can benefit entire communities, including families who lack the means or ability to access rooftop solar themselves.

In addition to Craig and Shi, the other author of the paper is Shi Lu of Tsinghua University.