- Analysis of 1,000 solar PAYG home systems shows a general decline in household energy consumption over time.
- Five distinct daily usage profiles highlight underutilisation and the need for better system sizing.
- Findings suggest behavioural changes beyond financial constraints influence energy use, with implications for cost and system design.
A recent study published in Energy for Sustainable Development, titled ‘Understanding long-term energy use in off-grid solar home systems in sub-Saharan Africa,’ provides one of the most comprehensive analyses to date of energy use in ‘pay-as-you-go (PAYG) off-grid solar home systems in sub-Saharan Africa. Researchers tracked 1,000 systems over several years, using advanced clustering techniques to map daily load profiles and identify patterns in household energy behaviour.
Pay-as-you-go solar across Africa allows low-income households to access solar home systems through affordable, incremental payments rather than large upfront costs. Users typically make payments via mobile money platforms, which then activate or extend their electricity supply. This model has attracted digital and telecommunications companies into the energy sector, but its success depends on consistent repayments in economically vulnerable contexts characterised by irregular incomes and inflation. It also faces a structural limitation: many households have little scope to increase their electricity expenditure, and in areas served by the grid, off-grid solar often ends up being more expensive than grid-supplied electricity.
The study identified five archetypal daily usage profiles ranging from low use to double peak consumption. Analysis revealed that households only fully utilise their systems around a quarter of the time, with moderate and nighttime use dominating daily consumption. Energy use tends to peak within the first 100 days of ownership and then gradually declines, with a 33 percent reduction on average by the end of the second year. Importantly, the decline occurs even in households that are not facing economic hardship, indicating behavioural changes beyond financial constraints.
The research also highlights economic and design implications for solar home systems. Frequent underutilisation suggests that many systems are oversized, which increases costs for both suppliers and households. Economic outages remain a reality under pay-as-you-go models, but they do not fully explain the decline in energy use. The study calls for adaptable system designs and pricing structures that better align with actual household needs. This could include downsizing systems over time or providing more flexible energy solutions to ensure long-term adoption and cost-effective energy provision.
The findings underscore the importance of understanding user behaviour to improve the sustainability and affordability of off-grid solar energy in Africa. As solar home systems continue to expand across rural communities, aligning technology and pricing with real-world usage will be critical for achieving both energy access and economic efficiency.
