Energy poverty is an endemic phenomenon affecting millions of households around the world. An abundant literature, employing various single or combined methods, is dedicated to understanding its causes, symptoms, and the lived experiences of these households. This article explores the challenges raised when implementing qualitative research on energy poor households. We analyse a set of 33 research outputs - academic papers and reports - to identify methodological challenges raised by researchers and their possible resolves. By discussing the difficulties related to the operationalization of the concept of energy poverty, those linked to identifying and engaging energy poor households in research, or to the complex nature of their vulnerabilities, the study aims to develop a grounded theory articulated on the narrative of the findings and provide guidance for future qualitative work on energy poverty performed by researchers and stakeholders involved in alleviating it.