Most U.S. residential rooftop solar customers finance their solar purchases through loans or by buying power from third-party owned systems. Prior research demonstrates how third-party ownership (TPO) models such as leases emerged in the early 2010s and accelerated solar adoption by low- and moderate-income households while driving market concentration in the installation industry. Since 2015, loans have emerged as a prevalent financing alternative, but the potential effects of loans on the customer base and industry remain understudied. Here, we fill that research gap by developing a methodology to identify loan-financed and third-party owned systems in a household-level solar adopter data set. The data suggest that loans accounted for increasing solar market shares from 2017 until reaching as high as 70\% in 2022, but that the market has since shifted back to TPO. The data show that TPO adopters in our sample earned about 16\%{\textendash}18\% less and loan recipients earned 3\%{\textendash}7\% less, at the median, than customers who self-financed systems. These results reaffirm prior research showing that TPO has accelerated low- and moderate-income adoption and that loans have likewise expanded the customer base to a lesser extent. The results suggest that loan-financed systems entail around a 16\%{\textendash}26\% price premium that is only partly explained by loan fees. Finally, the data suggest that the emergence of loans has likely reduced market concentration in the rooftop solar industry.
}, year = {2026}, booktitle = {Environmental Research: Energy}, journal = {Environmental Research: Energy}, series = {Environmental Research: Energy}, volume = {3}, month = {06/2026}, url = {https://iopscience.iop.org/article/10.1088/2753-3751/ae6fbd}, doi = {10.1088/2753-3751/ae6fbd}, note = {An open-access version of this article was published in Environmental Research: Energy and can be downloaded here.\
}, }