For purely economic reasons, there should be a lot more rooftop solar panels in the US. With the dramatic drop in the price of panels, solar systems have become competitive with electricity costs in a growing number of countries, so the issue of solar radiation is the main reason why adoption makes sense. However, homes equipped with photovoltaics remain a rarity in the US, although many states are pushing for the introduction of renewable energies.
Why doesn't this push work? To find out, a small team of researchers worked with a nonprofit that sponsors solar panels and helped test two different messages. One message focused on self-interest and emphasized the economic benefits of installing panels. The other was what was labeled "pro-social," which meant that installing solar energy would benefit the community. As the researchers found, self-interest was king – even after the promotion ended. However, self-interest had the side effect that the installed systems tended to get most of the energy out of their panels.
The work is based on a program called Solarize. Solarize runs city-level programs that include a single installer that offers the entire city on a group rate. Program ambassadors are also running pro-solar programs around the city to encourage adoption. These programs were targeted by the researchers, who arranged an experiment based on the message from these ambassadors. Some cities received messages that focused on self-interest, such as "Save thousands by installing solar energy". Others were more community focused – “Our community is doing something together to have more clean energy,” for example. The researchers worked with the Connecticut program (one of the researchers is at Yale) which has expensive electricity.
Previous polls among Solarize attendees suggest that both messages could find resonance. Of the three main reasons participants took part in the program, two related to economy (low prices and savings on electricity bills) and the other related to the environment.
To turn this into an experiment, the researchers identified groups of three cities that roughly matched demographically. These cities were then divided so that one received a selfish message, another received the pro-social message, and one did not participate in the Solarize program. Due to some financial problems, one of the planned programs did not occur, so that the experiment was carried out with 29 cities and a total of almost 700,000 participants. Existing trends and household data were obtained using Connecticut data for all state solar systems and data from the US Census Bureau. Participants also received follow-up surveys.
Overall, the Solarize program was effective and resulted in more installations than in the control communities and higher trends than in the participating cities. And during the campaign, self-interest messaging resulted in higher overall installations than in cities where pro-social messaging was received. While cities that received pro-social messages had a higher installation rate than control cities, the difference was not statistically significant.
Additionally, self-interest messaging resulted in more productive installations. Using Google's solar calculator, the authors estimate that the panels installed in response to these messages receive more sunlight on an average day and produce an additional 4.4 megawatt hours over the life of a typical system. This is in line with the fact that the people who received the selfish messages cited money as the primary reason for installing solar. Additionally, they prepaid their systems rather than borrowing, which increased the return on the purchase.
Unsurprisingly, this type of message works better in high-income communities too. There is some evidence that pro-social messaging works better in low-income communities, but the results were not statistically significant. The one thing that was consistently true for those who received the pro-social message was that they reported that they were more satisfied with their installations and were more likely to recommend Solar to their friends and neighbors.
Overall, the researchers suggest that there is no single message that could get people to install solar energy. For those with the option to prepay installations, it seems like the way to go about addressing financial concerns. In the meantime, community-centric messaging can attract consumers who may not be in the financially strongest position but are primarily motivated by environmental concerns – and willing to install panels in less productive locations.
The value of getting the message right isn't limited to the campaign itself. The researchers also had data from after the campaign ended and found that the effects of the self-interest messages lasted for almost two years. Rather than being a result of exposure to the campaign, the researchers suggest that exposure to the panels themselves – which are now in more of their neighbors' homes – spark further interest in the technology. That makes it clear how important it is to get the right message across if we want to continue expanding renewable energies.
PNAS, 2020. DOI: 10.1073 / pnas.2004428117 (About DOIs).