Solar Photovoltaic Systems Adoption for Passive Houses in New Zealand: A Mixed-methods Analysis of Trends and Influencing Factors

Abstract

Solar photovoltaic systems (SPVS) can complement Passive Houses (PHs) by reducing grid dependence, emissions, and household energy costs. However, existing SPVS–PH research has emphasised technical performance and modelling, with limited attention to stakeholder, financial, policy, and market factors shaping adoption. This gap is evident in New Zealand, where SPVS uptake is increasing in conventional housing but remains limited in PHs. This study investigates the trends, drivers, barriers, and strategies influencing SPVS adoption in New Zealand PHs.

A sequential mixed-methods approach was used, comprising document analysis, 34 interviews, and a survey of 96 building and energy professionals. Qualitative data were analysed thematically, while survey responses were examined using mean ranking (M), one-sample t-tests, and reliability testing in Statistical Package for the Social Sciences (SPSS). Findings show that New Zealand's SPVS capacity reached 573 MW in 2024, while PH Plus and Premium certifications remain limited but are gradually increasing. Interviews identified 13 drivers, 18 barriers, and 18 strategies. Survey results ranked the strongest drivers as low-carbon transition support (M = 4.57), and declining SPVS costs (M = 4.55). The strongest barriers were budget constraints (M = 4.09) and low solar buy-back rates (M = 3.87); the strongest strategies were optimised design and installation (M = 4.54) and battery integration (M = 4.53).

Although limited to stakeholder perceptions in New Zealand, the study shows adoption is shaped by financial viability, policy support, and early-stage design integration, thereby contributing to Sustainable Development Goals 7 (Affordable & Clean Energy) and 13 (Climate Action).