The sales data come from the GOGLA / Lighting Africa report on H2 2017, and include only quality-verified pico-solar (<11 W) and solar home system products, c. 30% of all. The other 70% are generic products, usually of low quality. The investment data come from the Off Grid Market Trends report 2018.
See the two reports for discussion of why (drought, currency, demonetisation etc) …but the bottom line is that we are struggling badly, as things stand, on what should be a relatively easy Sustainable Development Goal: number 7, clean and affordable energy for all by 2030. See also the taster chapters of my book The Test – currently being lived. Bottom line: the reasons are compound, but all fixable ….in principle. That is the test.
Image: chart constructed from data in the report