I had experience in engineering solar hot water systems and prototyping small solar photovoltaic (PV) systems. I thought I knew what I needed to know in order to build a large off-grid PV system. I didn't know what I didn't know. This book is designed for engineering-minded people who want to design, construct, and operate their own PV system, sufficient to run a mid-sized cabin, that works completely off-grid. This book describes in detail suggestions, based on experience, of what to do, and what mistakes to avoid. This project is somewhat more complicated than is often suggested and the author warns the reader about how difficult it may be to do this. However, the author's experience is that it is feasible. The subtitle is intended to convey that one should consider this project carefully. This book is intended to help one do so, and be successful if the decision is made to proceed. Repeating my mistakes is now optional.