Background: Solar photovoltaic (PV) plants can contribute to the transformation of the electricity system in Sweden not only by adding capacity, but also by forming new decentralized ownership structures and involving new actors. This article focuses on solar PV plants on larger buildings, which represent a significant share of the installed capacity (although the total capacity is still very low in Sweden) and which have a good future potential. We are interested in the reasons owners of large buildings have for investing in solar PV plants, despite the fact that they face a complex regulatory situation. The aim of this paper is, therefore, to identify added values from solar PV plants for large buildings and to see how these values contribute to the ongoing expansion of the solar PV niche in Sweden. We use sustainability transitions as the theoretical point of departure and focus particularly on the role of values in an expanding niche. Data was collected via 15 semi-structured interviews, mainly with large building owners. It provides an interesting empirical case of the pioneers within the actor group of large building owners who potentially can play an important role in the expansion of solar PV technology in Sweden. Theoretically, the article contributes to the sustainable transition research field by demonstrating how values are developed and affect the niche-regime interplay. Results: The findings demonstrate that owning a solar PV plant adds values such as sustainability, fair cost, and induced innovativeness. These values have an effect on niche expansion by contributing for example to the development of a social network, new role development, positive niche narrative, and niche empowerment. Conclusions: We conclude that the broad set of values added by solar PV plants on large buildings increases the desire and enhances the positive experience to take on a new role development. Furthermore, we conclude that added values contribute to developing a social identity which is important when expanding the social network around the niche. Finally, we conclude that added values shape the positive niche narrative among niche advocates and give direction for policy development related to the niche. © 2020 The Author(s).