Access to clean and affordable lighting services is an important part of addressing issues of equality, development and the environment. Flame based lighting, which is the primary source of light for over a billion people worldwide, is expensive, hazardous for users, and environmentally damaging. In the last decade, off-grid lighting technologies like light emitting diodes (LED) and compact fluorescent lights (CFL) have emerged as a bridge between the traditional flame-based lighting and access to the electric grid. This study includes an evaluation of current empirical and analytical methods for estimating the daily operating time of solar charged off-grid lighting products. The study also explores low cost measures to improve the accuracy of these methods.