Shining light on the scale, use, and impact of household solar for achieving energy access in rural Malawi.

Over 760 million people, primarily in sub-Saharan Africa, still lack electricity access. Off-grid solar is central to electrification strategies, yet most evidence treats all solar adoption as equivalent, without distinguishing between system capacity or household use patterns. This obscures a critical policy question: do small devices meaningfully advance progress toward global energy access, or are greater capacity and specific uses required to unlock impacts on household welfare? Using two waves of survey data from 1,030 rural Malawian households, we combine difference-in-differences estimations with an innovative energy budgeting exercise and latent class analysis to assess how households use their energy supply and how device capacity impacts households' experiences. Small solar devices (<5 W) are predominantly used for phone charging, reducing charging-related travel by 1-hour/week but yielding no other impacts. Households adopting 5-50 W devices gain 20 extra hours of lighting/week and primarily use solar for security while sleeping or for lighting for domestic tasks. The largest benefits accrue to households adopting >50 W, increasing lighting by 35-50 hours/week and time for productive activities by 3.5 hours. Our findings show that tracking solar adoption without considering capacity risks overstating progress toward Sustainable Development Goal 7 (modern energy for all). To reflect this reality, national surveys should report device capacity and use, and electrification strategies should prioritize affordable, modular pathways for households to reach at least Tier 2 status (>50 Watts). Framing policies around capacity and use, not just adoption, will ensure off-grid solar products are able to deliver social and economic benefits.