How are these two approaches conducted? And how do they use “Semi-structured Interviews” as a qualitative research?

This order is part of a masters dissertation in a UK university. The topic of the dissertation is: “Financial Evaluation of Grid-Connected Solar Photovoltaic Systems in Healthcare Facilities within the UK”. The aim of this research is to provide an understanding of two financial elements that prevent decision makers within the healthcare facilities from investing in grid-connected solar PV systems; ‘cost competitiveness’ and ‘payback period’.In the methodology, the rationale for selecting certain approaches that incorporate a “Semi-structured Interview” MUST be provided through answering the following: What are the “Holistic Case Study” and the “Embedded Case Study” approaches?
What are the advantages and disadvantages of these two approaches?

What are the expected outcomes from these two approaches and from the “Semi-structured Interviews”?(Please use only books and academic journals as sources)