The synergy of cool roofs and solar systems

By Emma Peterson. 

Learn how cool roofs and solar panels can work together to meet rising energy demands.  

The Energy Information Administration reports that “the projected power demand of the U.S. will rise to 4,199 billion kilowatt-hours in 2025 and 4,267 billion kWh in 2026.” These are record highs, with 2024’s 4,110 billion kWh being the latest record. As we look for ways to meet these rising energy demands, many experts have started looking to the rooftops. To learn more about this, we hosted Audrey McGarrell of the Cool Roof Rating Council (CRRC) for an episode of Roofing Road Trips® all about mitigating rising energy needs with cool roofs and solar systems.  

Starting with the basics, “A cool roof is one that strongly reflects sunlight (solar energy) and also cools itself by efficiently emitting any heat that was absorbed. The roof literally stays cooler and reduces the amount of heat conducted into the building below.” By itself, a cool roof lowers energy bills, extends roof service life, mitigates urban heat islands and addresses air pollution concerns. As for solar systems, more specifically photovoltaic systems or PV systems, they lower the energy demands on the local electrical grid by providing the building they are installed on with an independent, renewable energy source.  

Alone, both of these technologies are powerful ways to build a more energy-friendly and sustainable future. But what is often overlooked is the symbiotic relationship between the two. Audrey explained, “There was a broad range of studies looking at different climates, different solar panel types and orientations and all of these things. And what they found was a linear relationship between solar and reflective roofs.” 

There are generally two types of solar panels on the market, monofacial and bifacial. The big difference between these two is where they can absorb solar energy from; monofacial panels can only absorb on one side where bifacial panels can absorb from both sides.  

As you might deduce, the bifacial panels have the most drastic performance increase when paired with a reflective roof. Audrey gave an example, sharing, “If you were to raise a roof's solar reflectance from a baseline of 0.15 up to a solar reflectance of 0.6, you could actually see an increase in solar panel power output of about 20%. And if you went all the way up to 0.8 solar reflectance, the increase is almost 30%.” 

And just because it’s not as dramatic of a performance increase doesn’t mean that monofacial solar panels don’t also benefit from being installed in combination with reflective roofing! Audrey gave some numbers on that, sharing, “If you were to increase the solar reflectance of a roof from 0.15 to 0.25, which there are plenty of products on the market that would fit that value, you could see a 1% increase in monofacial panel output.” 

To make it easier for contractors and building owners to explore the possibilities of a reflective roof with solar, the CRRC has created a new educational resource on the synergy between the two. Audrey shared a bit about it, saying, “What we came up with and put in this document are some examples of how raising your roof solar reflectance from X to Y could impact your solar panel output.” You can explore the resource yourself on the CRRC’s website. 

Check out the whole podcast to learn more about this incredible resource and the relationship between cool roofing and solar panels!