At Solar Sister, we recruit women entrepreneurs in last-mile communities and support them in launching businesses that distribute clean energy products in their communities. Solar Sister Entrepreneurs earn income and valuable business and leadership skills, but the impact of the Solar Sister model extends beyond the entrepreneurs themselves. To calculate the positive impact of clean energy distribution in Solar Sister Entrepreneur communities, Solar Sister utilizes the Standardized Impact Metrics for the Off-Grid Solar Energy Sector, developed by the Global Off-Grid Lighting Association (GOGLA). GOGLA’s framework was built by an Impact Working Group of off-grid solar practitioners, researchers, and data experts, and it’s used by companies, investors, and organizations across the sector — including many of our peers — so that everyone is speaking the same language when it comes to clean energy impact.
The methodology works by taking the number of units sold (adjusted for product loss, damage, or products that don’t reach end-users) and applying a set of research-based variables specific to the regions our entrepreneurs work in to estimate outcomes like energy access, income generation, and CO2 reduction.
Solar Sister’s Impact (through 2025)
Using this methodology, here’s what our entrepreneurs’ clean energy sales are estimated to have achieved:
| Metric | Estimated Impact |
| People with improved energy access – Cumulatively since 2010 | 5,821,665 people |
| People undertaking more economic activity – Currently | 16, 174 people |
| People using products to support enterprise – Currently | 10,522 people |
| People who spend more time working – Currently | 5,922 people |
| Additional income generated – Cumulatively since 2010 | $61,550,499 |
| Money saved – Cumulatively since 2010 | $240,026,233 |
| Kerosene lanterns replaced – Currently | 101,012 lanterns |
| CO2e mitigated – Cumulatively since 2010 | 2,217,032 metric tons |
How the calculations work
For each metric, GOGLA’s formulas start with our verified product sales data and apply standardized variables drawn from years of sector research. Here’s a simplified look at how each of the metrics we highlight is calculated:
People with improved energy access: We take the number of products sold, adjust for any that were lost, damaged, or never reached an end-user, then adjust again to avoid double-counting repeat customers. That figure is multiplied by average household size to estimate the number of people — not just customers — now living with better access to light and power.
People undertaking more economic activity: This estimates how many people use their new solar product to do something economically productive — extending their working day, running a shop, or supporting a home-based business. GOGLA applies a research-based percentage (regionally specific) of customers who report taking on more economic activity, then multiplies by a “people per household” ratio, since these benefits often extend beyond the original purchaser to others in the household.
People using products to support enterprise: A related but distinct metric, this estimates the number of people using their solar product specifically to support an existing enterprise or start a new one. It uses its own regional-specific percentage derived from customer research.
People who spend more time working: Some customers use their extended hours of light to work longer. This metric applies the percentage of customers who report spending more time working, multiplied by the same household ratio, to estimate total people affected.
Additional income generated: This combines the percentage of households reporting additional income with the average additional income generated per household annually (a figure grounded in regional-specific survey data), scaled across the estimated lifespan of the product to calculate cumulative additional income.
Money saved: This compares what a household used to spend on energy before they had a solar product, against what they spend afterward. GOGLA takes the difference between baseline and post-purchase energy expenditure, multiplies it across the product’s estimated lifespan, and then subtracts the cost of the solar product itself to estimate the net savings a household actually keeps.
Kerosene lanterns replaced: Using an estimate of how many kerosene lanterns, on average, a solar product displaces in each region and the estimated lifespan of a solar product, we estimate the total number of lanterns that are currently taken out of use.
Kerosene lanterns replaced: Using an estimate of how many kerosene lanterns, on average, a solar product displaces in each region and the estimated lifespan of a solar product, we estimate the total number of lanterns that are currently taken out of use.
Every formula above uses GOGLA’s default, research-derived variables rather than optimistic assumptions of our own — which is part of why we trust this methodology, and why we think you can too.
A note on transparency
We believe impact reporting is only useful if it’s honest about what it can and can’t tell us. These figures are estimates, calculated according to a rigorous, sector-standard methodology. We share our methodology openly because we want our supporters, partners, and entrepreneurs to trust not just our numbers, but how we got there.
