Solar irradiance is the energy per unit area received from the sun as electromagnetic radiation within the wavelength range of the measuring instrument, typically measured in kilowatt-hours per square meter (kWh/m2) in the solar industry. Understanding solar irradiance is fundamental to unlocking the solar potential in the "Giant of Africa," Nigeria.
Basics: The geography, climate and solar irradiation of Nigeria
Learning about the solar irradiation of Nigeria requires a general understanding of its geography and climate.
As a West African country, Nigeria is located between latitudes 4°-14°N and longitudes 3°-15°E, covering an area of about 923,768 km2. The climate of the country is generally classified as tropical monsoon in the south, tropical savannah in most of the central regions, and Sahelian hot and semi-arid in the north.
In more detail, southern Nigeria's temperatures and humidity stay relatively constant throughout the year. The mean monthly minimum temperatures in this region are around 20℃, while the mean monthly maximum figures reach 33℃. In contrast, northern Nigeria's temperatures vary considerably. In the northern city of Maiduguri, the mean monthly maximum temperature may exceed 38℃ during hot months. At the same time, Central Nigeria is known for its distinct dry and rainy seasons. Its dry season typically runs from November to March, while its rainy season occurs between April and October.
As we all know, solar energy generation is greatly influenced by climate, but comprehending its effect requires a thorough study based on the location, configurations and even operational status of the project. Unlike this, solar irradiation does most of the jobs and gives project developers a straightforward picture of the solar potential in a region.
A 2015 paper studied 26-year (1984–2009) daily solar irradiance data measured from satellites over 25 locations in Nigeria shows that the contour maps of the averaged daily solar irradiance and clearness index over the locations indicate there is a noticeable variation from north to south. The highest solar irradiance and clearness index can be found at the northern horn of the maps, while it gradually decreases as moving southward.
A 2020 research analyzed data obtained in a 5-minute interval over a period of one year. The findings reveal that solar irradiation in northern Nigeria falls in the range of 5.62-7.01 kWh/m2, while in the south, the range is 3.54-5.43 kWh/m2, suggesting that northern Nigerian locations have greater solar irradiation than the southern.
A 2019 study took akin research to the next level, which examined solar irradiation of three typical locations (representing three climate zones in Nigeria, respectively) and correlated them with the same solar project demand. The results indicate that the northern city of Maiduguri has the highest average daily solar irradiance and requires the lowest cost to develop the designed project.
Nowadays, companies like Solargis use high-quality satellite imagery and data and combine them with advanced analysis methodology to provide project developers with professional solar resource data and software solutions. The latest Global Photovoltaic Power Potential study, which leveraged Solargis' expertise, presents both direct normal irradiation and global horizontal irradiation of Nigeria, based on which practical PV potential (represented by PVOUT) and economic PV potential (calculated for large-scale ground-mounted PV power plants and described by LCOE) are evaluated. The results show that Nigeria has an average theoretical solar irradiation of 5.44 kWh/m2 and PVOUT of 4.30 kWh/kWp.
Overview: Solar development in Nigeria
According to World Bank statistics, Nigeria's population had reached 213.4 million as of 2021, ranking #1 in Africa and #7 in the world. Its GDP (PPP) in 2022 was around $2,022.89 billion, ranking #1 in Africa and #18 globally. Authorities maintain a relatively optimistic estimation on the average GDP growth rate for the period from 2023 through 2024 at 3.3%, in the post-COVID era and under the fluctuating socioeconomic environment.
Current energy state
"Improving access and reliability of power is key to reducing poverty and unlocking economic growth." In spite of the fact that electricity forms the foundation of economic development, Nigeria's electricity access rate in 2020 stood merely at 55.4%, with a significant gap between rural and urban areas (83.9% vs. 24.6%).
Reliance on traditional fossil-fueled electricity has been proven to be costly and unstable, attributed to the rising and fluctuating energy prices, inefficient deployment, high labor and infrastructure costs, as well as increasing threats to the climate. According to recent reports, Nigerians may experience over 40% increase in electricity tariffs from July 1 due to current high gas prices.
Solar capacity and development
Today, 80% of power generation in Nigeria comes from gas, while solar capacity only accounts for a small portion. Known for the advantages of relatively low LCOE, efficient deployment for remote areas, strong capability to improve electricity resilience (especially when paired with storage) and environmental friendliness, both international institutes and the Nigerian government have rolled out a series of solar initiatives and programs to increase solar's share and boost electrification.
The Sustainable Energy Fund for Africa (SEFA) by the African Development Bank offers technical assistance and concessional finance instruments to remove barriers to solar and renewables deployment. The U.S. Government-led partnership Power Africa brings together collective resources to increase energy access through renewables in sub-Saharan Africa, including Nigeria. With the support of this initiative, a series of solar mini-grids and hundreds of solar home systems have been set up at many most-needed sites in the country.
Over the years, the Nigerian government has also committed itself to accelerating the development of solar power. To name a few, in 2021, the Nigerian government launched the Solar Power Naija (SPN) to expand electricity access by providing five million off-grid solar home systems as well as facilitate local solar manufacturing and create 250,000 new jobs in the energy sector. Moreover, the Nigerian Central Bank (CBN) introduced its solar intervention fund to encourage the development of diverse off-grid solutions.
In light of Nigeria's high solar irradiation, a U.S. authority gauged that the country has about 427 GW of solar potential. While a report titled Renewable Energy Roadmap for Nigeria estimated that 5 GW and 25 GW of utility-scale solar power can be produced by 2030 and 2050, respectively; as for the off-grid solar system, it is expected to provide 13 GW by 2030 and 29.5 GW by 2050.
Final words and some notes
All the existing efforts and various encouraging projections are built upon Nigeria's impressive solar irradiation figures and the reduced costs of solar components. However, accurate solar irradiation on a particular site should examine its surroundings and the specific geographic factors of the site; meanwhile, further measures should be carried out to further drive down the costs.
As an emerging solar market, Nigeria necessitates a systematic framework to enhance its solar development. Many challenges persist when exploring solar adoption, one of which is access to sufficient finance. To our pleasure, more and more helpful financing options are offered to ease the adoption of solar, such as power purchase agreements (PPAs) and pay-as-you-go solar. Additionally, a large number of small-scale solar applications without high upfront costs, like solar home systems, are being deployed to accelerate the electrification process. Affordable solar-powered street lights and solar-powered irrigation pumps are also popular among businesses.
Secondly, Nigeria needs to develop its domestic solar value chain to further reap the benefits of solar energy, contributing to sinking reliance on equipment import, stabilizing supply and, more importantly, lowering the costs and enhancing the competitiveness of solar.
Considering its inspiring solar irradiation data alongside strong demand for socioeconomic development, the solar potential in Nigeria can be deemed as huge. More tailor-made approaches and transnational cooperation are needed to unlock the potential and fuel growth, though.