Since 2010, 42 million off-grid solar lighting products have been sold, and in 2018 alone the sector raised close to USD 352 million in investments. As business models become more complex and forge deeper to reach the last mile, it is important to have a granular understanding of the unit-cost economics that serve as the building blocks for sustained profitability. While profitability through economies-of-scale holds true in some business models, it may not for others, and can very well undermine the performance of the entire organization. From an investor’s perspective: What do companies need to do to reach scale? What is a reasonable time-frame to scale? Are there business models we should consider if we want to attain scalability faster?