The potential of solar-powered irrigation has been known for some time. Research from the UN in 2018 showed significant potential for the technology to increase sustainable water use and help farmers adapt to changing weather patterns.

‘Sub-Saharan Africa has a high potential for solar-powered irrigation, and Southern Africa even more so,’ says Felix Reinders, chair of the Global Framework on Water Scarcity in Agriculture, based in Pretoria, South Africa.

‘Most areas in Southern Africa average more than 2 500 hours of sunshine per year, and average solar-radiation levels range between 4.5 kWh/m² and 6.5 kWh/m² in one day. This makes Southern Africa’s solar resource one of the highest in the world.’

More recently, however, a study has found that standalone solar PV irrigation systems have the potential to meet more than a third of the water needs for crops in small-scale farms across sub-Saharan Africa.

This is a bold claim, considering 80% of agricultural production in the region comes from smallholder farmers, who rely mainly on rain-fed agriculture (90% of all crop land) under unpredictable and erratic rainfall. Widespread adoption of solar irrigation systems could have a profound impact on food insecurity and economic development, helping countless communities escape the poverty trap caused by cyclical famines.

The researchers, led by Giacomo Falchetta from the International Institute for Applied Systems Analysis, developed a modelling framework that analysed data related to agriculture, water, energy, expenses and infrastructure. This was then used to calculate local irrigation needs, determine the necessary size and cost of technology components such as water pumps, solar PV modules, batteries and irrigation systems, and assess the economic prospects and sustainable development impacts of adopting solar pumps.

‘In the context of our study, we focused on smallholder farmers because they cultivate the vast majority of agricultural land in the continent and they are the main producers of staple crops,’ says Falchetta. ‘We believe solar irrigation is particularly promising for them as it is scalable, linkable to smart business models to overcome financial barriers, and has very low operational and maintenance costs. Moreover, it can strongly support yield growth and stabilisation, as most smallholder farmers practise rain-fed agriculture today.’

There are signs that adoption of the technology is making headway throughout the continent. In Uganda, more than 300 small-scale farmers will receive solar irrigation systems under the Uganda Intergovernmental Fiscal Transfer programme, with the first 32 to be rolled out by the end of 2024. (Eighty percent of Uganda’s fertile agricultural land is arable, and has the potential to feed 200 million people – yet only 35% is being cultivated, according to the UN’s Food and Agriculture Organisation.)

To the west, in Togo, the AfDB has financed 153 immersion and surface pumps for local farmers, as part of a rural electrification scheme to promote solar energy in rural areas through off-grid solutions.

Farmers in landlocked Mali will benefit from a new partnership between AICCRA (Accelerating the Impact of CGIAR Climate Research for Africa) and solar irrigation supplier Ecotech that will facilitate access to solar irrigation in the form of a pay-as-you-go business model, transferring ownership to farmers over time. And in Rwanda, around 144 rural women in the Ngoma district have formed a successful farming co-operative thanks to a solar-powered irrigation intervention supported by several UN agencies.

These success stories all point to one of the biggest obstacles to widespread adoption of solar-powered irrigation – cost. Solar pumps require an investment of anywhere between US$840 and US$4 700, according to one estimate, placing them out of reach for the vast majority of rural farmers who do not have access to financial aid. ‘There has been a lag in the development of solar-powered irrigation in Southern Africa, mainly due to the high investment cost associated with solar technology,’ says Reinders.

Still, solar is arguably a more environmentally and economically sustainable option than traditional energy sources for irrigation in remote locations. ‘The biggest energy supply for pumping irrigation water is still electricity,’ says Reinders. ‘But diesel-, gas- or petrol-driven pumps are also popular in areas where there is no electricity.

‘Such conventional pumps, however, have the double drawback of requiring a lot of maintenance, as well as a regular supply of fuel and physical attendance for operation. In remote areas of developing countries in particular, access to spare parts, maintenance structures or fuel can be limited, leading to frequent outages of several days or longer. With the right knowledge on proper use, operation and maintenance of solar photovoltaic pumps, failures are much less likely than with conventional pumping systems.’

Falchetta and his colleagues address the subject of financing in their research, emphasising the importance of business models and investment incentives, crop prices as well as PV and battery costs, in shaping the economic feasibility and profitability of solar irrigation. They estimate that an average discounted investment of US$3 billion a year could generate potential profits of more than US$5 billion per year from increased yields to smallholder farmers, as well as significant food security and energy access co-benefits.

‘Allowing instalment payments or pay-as-you-pump payment schemes would have a dramatic impact on the economic feasibility of solar irrigation from the point of view of farmers,’ says Falchetta. ‘In turn, these schemes necessitate a vibrant entrepreneurial environment, which can only exist when enabling regulatory and governance conditions are in place.

‘Of course, business models should be coupled with training and knowledge sharing to inform the farmers about the benefits of irrigation and solar water pumping, as well as with technical knowledge on its use and maintenance.’

Indeed, raising awareness and educating farmers about the benefits (and even the existence) of solar-powered irrigation is another ongoing problem being tackled by many African countries.

For example, in 2021, a Kenyan TV show – Shumba Shape Up – took on this challenge, seeking to share knowledge about access to financing; various solar irrigation systems, their application and maintenance; cost-effectiveness; as well has how to use water resources sustainably. In Tanzania, the Water and Energy 4 Food programme has taken on this awareness-raising role. This education is essential not only to fast-track adoption, but also to ensure farmers manage water responsibly. The continent’s vast underground water reserves are under pressure from climate change, a situation that could be exacerbated by over-extraction of groundwater from solar pumping, with serious consequences for communities and the environment.

A UK social enterprise and solar pump manufacturer, Futurepump, however, has come up with an innovative solution – high-tech solar pumps mapping underground freshwater reservoirs across Africa, collecting data that can help prevent them from running dry. The WEF reports that these pumps are being used by thousands of small-scale farmers across the continent as a cleaner, cheaper option to diesel and gasoline-powered ones.

‘The pumps’ sensors record real-time data such as energy usage and pump speed in each location, which is shared with the International Water Management Institute to calculate groundwater extraction rates and levels,’ it states.

Solar-powered irrigation is undoubtedly a transformative tool, yet it also comes with the potential for mismanagement, so it is encouraging that solutions to potential fallout are being developed in lockstep.

As ever in the developing world, overcoming financial barriers and ensuring equitable access to technology remains a significant challenge. Yet a commitment to supplying this technology at scale on the continent is evident, and progress is being made – one drop at a time.

By Robyn Maclarty 
Images: Pexels, Future Pump