Small solutions making a big impact

April 26, 2018

While many in the energy sector believe bigger is always better, Solar Sister knows from experience and data that for people living in last mile communities, small clean energy solutions have transformational impacts.

Solar Sister’s approach focuses on “first light, last mile.” This means that we prioritize reaching customers who are underserved by the market and the current sector at large with solar solutions they can afford.

The majority of products sold by our network of entrepreneurs are portable solar lights that meet the most urgent energy needs of our consumer base. Data shows that these lights (like the d.light A1 or SunKing Pico) not only replace kerosene and battery-powered torches in households, but have transformative economic, educational, and health impacts on rural households. These lights, costing around 5-10 USD each, can also be bought on a cash basis, precluding the need for people to assume credit burden.

This blog pulls data from Santa Clara University’s research study conducted in 2016, “Turning on the Lights: Transcending Energy Poverty Through the Power of Women Entrepreneurs.”  Researchers from the Miller Center for Social Entrepreneurship interviewed 257 Solar Sister customers across 20 villages in rural Tanzania.

One of our key goals at Solar Sister is reducing energy poverty, which means helping our customers transition away from kerosene and other harmful energy sources. We target households at the base of the market pyramid through locally-based entrepreneurs who provide solar solutions and after-sales services. Almost all of of our customers (97.8%) reported using kerosene before purchasing a solar light from an entrepreneur, spending an average of 2,904 TZS (just over 1 USD) per week in lighting costs. After buying solar light, a fraction of customers (8.4%) reported continuing to  use kerosene.

Adopting solar lights also resulted in economic gains through savings and income generation among customers interviewed. Mark Correnti, Director of Impact Investing at the Miller Center, recently highlighted these findings in a March 21 webinar, Market Development for Renewables in Rural Communities, led by Shine, World Resources Institute and the Miller Center. Correnti highlights how critical small solar products can be in a context where the average daily income of rural Tanzanians ranges from $1-$2. The study found that a quarter of respondents started new businesses and increased their weekly income by over 100% (an increase of 13 USD). Over a third (38%) strengthened existing businesses and saw their average weekly income increase by over 7 USD. Businesses where solar lights impacted success are highlighted in the graph below.

Beyond economic impacts, households adopting portable solar lights experienced improved educational and health outcomes. Almost all off-grid parents (90.6%) report that children’s academic performance improved since their households started using solar lanterns. Customers also note significant reduction of coughing and eye problems.

And what happens when women in particular obtain solar products? The Miller Center study found significant differences in how men and women use solar products. Women who adopted solar lights were more likely to use them for productive uses, while men overwhelmingly used the same products for leisure activities.

While Solar Sister works to help last mile customers transition up the energy ladder, we also recognize that there is unmet demand at the first step of the ladder that includes smaller and cheaper products. This first step gradually introduces customers to solar lighting, avoids putting them in debt or subject to long loan periods, and achieves efficient impact.


Last Mile Learning is a monthly blog series by Grants and Impact Manager, Abby Mackey. The series shares Solar Sister’s experiences, data and learning from our work with women-run renewable energy businesses in Nigeria, Tanzania and Uganda.