New report sheds light on residential solar adoption in terms of access and equity

Solar-adopter incomes presently skew high in all states, but, as with the national trends, that skew has diminished over time in most states.

Lawrence Berkeley National Laboratory released a report last week that highlights income, demographic, and other socio-economic trends among U.S. residential rooftop solar adopters. Galen Barbose, Sydney Forrester, Eric O’Shaughnessy, and Naïm Darghouth authored the report.

The latest edition in an annual series, the study is based on address-level income and other demographic estimates for roughly 1.9 million residential rooftop solar adopters across the country, representing 82% of all U.S. systems installed through 2019. The study updates and expands upon previous editions, describing solar-adopter income trends as well as trends in home-value, credit score, education, occupation, rural vs. urban, race and ethnicity, and age.

The report complements and informs other ongoing work at Berkeley Lab surrounding issues of solar energy access and equity, including an online data visualization tool, analyses around drivers and potential solutions to solar-energy adoption inequities, and technical assistance to other organizations.

Key findings

Solar adopters generally skew towards higher incomes, though that trend continues to diminish over time. Nationally, solar adopters’ median household income was roughly $113,000 in 2019, compared to the U.S. median of $64,000, or $74,000 if comparing just to owner-occupied households (Figure 1, left). That disparity has narrowed over time, with the gap between median incomes for solar adopters and all households shrinking by roughly one-third, from $72,000 in 2010 to $49,000 in 2019 (Figure 1, right). That downward trend in solar-adopter incomes is associated primarily with third-party owned (TPO) systems, as median adopter incomes for host-owned systems have remained relatively flat over time.

The incomes of people who go solar vary considerably and encompass many low-to-moderate income (LMI) households. Notwithstanding the general skew toward higher incomes, solar adopters span all income ranges, according to the report. Among 2019 adopters, 42% had household incomes below 120% of their area median income (AMI), a benchmark sometimes used to define LMI households, while 21% were below 80% of AMI, a more-stringent threshold often used to define low-income.

Those percentages have risen over time, as solar adopters have trended toward lower income households (Fig. 2, left). Solar-adopter incomes also vary considerably from state-to-state, with median solar-adopter incomes ranging from roughly $70k to $140k and from 104% to 162% of AMI (Fig. 2, right). That state-level variation partly reflects general geographical differences in income levels and income inequality within the broader population, but characteristics of state and local solar markets play some role as well (as other work by Berkeley Lab has sought to show). To be sure, solar-adopter incomes presently skew high in all states, but, as with the national trends, that skew has diminished over time in most states. Solar-adopter incomes also vary across individual installers, but skew high for almost all firms.

Solar-adopter incomes are consistently higher for systems paired with battery storage, for host-owned systems, and for systems installed on single-family homes. Median incomes are 22% higher for adopters of paired solar-plus-storage systems compared to stand-alone solar adopters within the same area, reflecting the additional cost of adding storage.

Consistent with prior work, the study also reaffirms that incomes are higher for systems that are owned by the homeowner, compared to third-party owned, by 23% when comparing among adopters in the same area. Finally, median solar-adopter incomes are 37% higher for systems installed on single-family homes compared to multi-family homes in the same area. In fact, the median income of multi-family solar adopters in 2019 was roughly equivalent to AMI.

Solar adopters differ from the broader U.S. population in terms of a variety of other demographic and socioeconomic measures. In addition to having relatively high incomes, solar adopters also tend to live in higher-value homes, have higher credit scores, have more education, be older, and are more likely to work in business and finance-related occupations than the U.S. population as a whole. As with the trend in income, however, those differences are generally diminishing over time. Solar-adopters also are less rural than the U.S. population as a whole, with 14% of solar adopters in 2019 living in U.S. Census-defined rural areas, compared to 19% of the total U.S. population. Those national trends largely reflect the fact that solar adopters skew toward less-rural states. At the individual state-level, solar adopters are typically more rural than the overall state population.

Solar-adopters tend to live in neighborhoods with relatively high non-Hispanic White and Asian populations, and with relatively low Hispanic and Black populations, compared to the rest of their state. Data on race and ethnicity of individual solar adopters were unavailable for this study, and so adopters were instead characterized based on the composition of their Census block group.

Comparing solar adopters to all households on a state-by-state basis shows that solar adopters tend to live in block groups with relatively high non-Hispanic White populations (Fig. 3, left), as well as relatively high Asian populations, and with relatively low Hispanic and Black populations (see full report for supporting details).

On a national basis, solar adopters would appear to live in block groups with relatively large Hispanic and Asian populations, and with relatively low White and Black populations, compared to all U.S. households (Fig. 3, right). However, those percentages are driven heavily by the fact that roughly half all adopters are in California, which has a very different makeup than the U.S. as a whole.

The authors will also host a webinar highlighting key findings from this study on April 22, 2021, at 11:00 AM Pacific/2:00 PM Eastern. Register for the webinar here.

Source: Renewable Energy