Access to electricity is widely seen as a cornerstone of sustainable development. It improves quality of life, enables household income generation, and raises living standards. Despite this, 760 million people around the world live without it.The gap is largest in Africa. Eighty percent of people without electricity connections live in sub-Saharan Africa, particularly in rural and hard to reach areas. Malawi is a small, landlocked country with one of the lowest electricity access rates in the world. In 2023, only 16% of Malawians had access to electricity – and access was just 6% in rural areas. Read more: Renewable energy will need more investment, or Africa will stay dependent on fossil fuels In Malawi, and many other countries in the region, grid electricity is primarily generated from hydropower. Grid electricity relies on outdated infrastructure that fails to meet demand or provide reliable energy services. Efforts to update and expand the grid are slow and costly. Off-grid solar provides an opportunity to bypass the long and costly grid infrastructure building process, making it a particularly attractive rural electrification strategy. Malawi’s off-grid solar market is rapidly expanding. Between 2020 and 2021, the market quadrupled in size. We are a research team of applied economists, geographers and environmental scientists. In partnership with a social enterprise (Vitalite, Malawi) we set out to uncover whether household solar systems could truly provide sustainable energy for all in Malawi. We surveyed 1,279 rural households in 28 villages in the southeastern region of Lilongwe District in Malawi, outside Lilongwe, the capital city. We asked whether households were adopting solar, who was adopting it, how they were using it, and what they were actually gaining. Our study focused on two common types of solar technologies that were already being sold in the area: solar home systems (packaged kits that include at least a solar panel, a control unit, light bulbs, and a battery) and stand alone solar panels (individual panels often combined with other components). Read more: How solar kits and battery lamps are replacing kerosene across Africa While solar technology is taking off in Malawi, we found that most purchases are for cheaper solar devices that only have enough energy capacity to charge phones and run small lights. Mainly wealthier families are adopting solar technologies and only the very wealthy can afford high capacity systems, which are needed to realise development impacts. This means that simply promoting solar isn’t enough to get the kind of electricity access to everyone that transforms lives. Financial support and higher capacity systems are needed.Solar spreads fast but access is unequalOur research found that among the families we surveyed, solar uptake was widespread but uneven. We found that by 2023, 34% of households owned at least one solar product, a 4.5% increase in ownership from the year prior, highlighting just how quickly these technologies are spreading. However, adoption was strongly linked to wealth. Wealthier households were significantly more likely to adopt solar technologies. Read more: Zambia’s forest communities need finance for solar power – so they don’t have to cut down trees to pay for it We also found that solar ownership was dynamic. Many households expanded their supply of solar technology through modular expansion. However, 29% of solar owners stopped using at least one solar device during our study period. Further, we found that the capacity or energy provided by household solar technologies was typically very low. The median device capacity in our sample was just six watts. This is only enough to power basic lighting and mobile phone charging.What households gained from solar adoptionFor households with small capacity solar devices of under 50 watts, the impact was small but meaningful. People spent less time travelling to trading centres to charge their phones and had additional hours of lighting at home. Many families used solar powered bulbs to keep lights on overnight for security reasons, making them feel safer.More transformative energy gains were realised by the few households with larger solar devices of over 50 watts. These devices allowed the people we interviewed to power businesses like barber shops or small food stores, and run lights for much longer. Importantly, we found these gains occurred for both men and women. Read more: Renewable energy projects in rural Ghana have some built-in limitations We also found strong links between solar adoption and financial inclusion. Solar owning households were significantly more likely to use mobile money, largely because they could reliably charge their phones at home. Further, solar owning households were nearly twice as likely to participate in informal savings groups because access to mobile money provides an easy way for groups to pool and save money. What needs to happen nextSolar technologies are expanding rapidly and clearly improve access to basic energy services. Increases in mobile phone charging, lighting, and greater financial inclusion are important gains in contexts where grid electricity remains out of reach. Limited availability and cost of higher capacity devices limits how much solar can transform livelihoods. For most households, solar currently supports daily convenience rather than deeper economic change. Read more: Grid or solar: looking for the best energy solution for the rural poor To achieve more transformative development impacts, policymakers and donors should focus on promoting access to greater capacity solar by supporting technologies that allow for modular expansion and improving financing options. Subsidies for lower income households and continuing to develop pay-as-you-go models are important options for expanding adoption and sustained use of solar technologies. With continued growth and investment in the sector, solar promises to play a critical role in achieving sustainable energy for all. (Andrea Mahieu co-authored this article and the research that this article is based on.)Congyi Dai is affiliated with Boston University Global Development Policy Center. Charles B.L. Jumbe, Pam Jagger, Ryan McCord, and Thabbie Chilongo do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.