Mobile phones are at the heart of the African telecom industry. Their use ramped up quickly, and “a decade after mobile phones began to spread, they have become commonplace,” The Economist reported in 2017. Today, even though fewer than 50% of Africans have access to electricity, mobile phones are very popular and their use continues to grow.
Ugandan Electrical Engineer Nelson Tashobya has seen Africa’s cell phone revolution firsthand and helped install the cell tower network mobile phones require. For five years, he worked for American Tower Corporation (ATC), which designed and installed over 20,000 cell towers in Africa, some of which are not grid-connected and rely on standalone energy systems. ATC Africa was one of the earliest adopters of HOMER® software, along with other companies serving the telecommunications industry in developing countries, including Africa, the Middle East and Asia.
We spoke with Tashobya about his reflections on the beginnings of the telecom industry and insights on how microgrids have helped telecommunications infrastructure providers keep pace with the rapid growth of the cell phone industry.
Please note that the following interview has been edited for clarity.
Could you please tell us about the evolution of the cell phone market in Africa?
The telecommunications industry skipped over landline technology almost completely in Africa and leapfrogged to cell phones. As a result, when cell phones became available, that market grew extremely fast. It is still rolling out rapidly across the continent. Hundreds of towers are being built every year. Despite this trend, there remains insufficient telecommunications service coverage in Uganda. This is the case in most of Sub-Saharan Africa.
Why did you need off-grid power for cell towers?
The simple answer is that the national grid access rate is low, averaging below 50% in Sub-Saharan Africa. According to the International Energy Agency (IEA), over 500 million people in Sub-Saharan Africa lack access to electricity. This is an acute electricity access deficit! In Uganda, where I am located, only about 65% of cell towers are connected to the national grid, and the rest are off-grid. This scenario is replicated in other ATC markets with small differences in the grid access percentages.
How did you provide power for cell towers when the technology was first deployed?
In the earliest days of the industry, off-grid sites had diesel generators running 24/7. This was not only operationally challenging in terms of frequent generator servicing and repairs, but it was also very costly. ATC deliberately sought innovations and technologies to reduce site power costs without compromising service-level agreements with their customers. ATC also desired solutions that would reduce carbon dioxide emissions, which aligns with the company’s sustainability goals. ATC eventually settled for solar microgrids with lithium-ion storage as the blueprint for all off-grid cell towers.
What were some of the design challenges you faced with these power sources?
Initially, the goal was to run a site generator for half the day and then run on batteries for the remaining half. That was a sound business case needed for ATC to invest in batteries for use in a hybrid power system.
The main challenge was how to correctly determine the optimal battery bank to deliver the desired performance. There were no proven in-house tools to support the design process, and we relied heavily on spreadsheet applications. While these helped us get started, they were limited because they are not a power-system design tool. The spreadsheet couldn’t adequately reflect the characteristics of generators, batteries and loads in the design analysis.
In 2018, through a colleague, I learned about a tool called HOMER that is specially designed for modeling hybrid power solutions. It was a timely discovery considering the business needs of ATC at the time. I was immediately interested in the tool, researched and downloaded HOMER Pro, paid for a one-month license, and started on a learning journey to understand how to use it to model power systems. Since then, I have used HOMER software for both grid-connected and off-grid power-system configurations.
When you first started using the HOMER Pro software, how did you calculate the loads for these systems?
We gathered the load data through an existing remote monitoring system.
What kind of batteries were you using?
Initially, we used lead-acid batteries at the cell towers. They have since been replaced by lithium-ion batteries, which have higher energy density and lower total cost of ownership (TCO).
Since HOMER Pro could show the net present cost of the various proposed system configurations, we were able to do technical and business case analyses with the same tool.
Nelson Tashobya
What role did the HOMER software play as your business grew?
HOMER Pro quickly became the tool of choice for modeling hybrid power systems. It was particularly key in determining a fully optimized solution considering multiple energy resource inputs, including power from the site’s generator, dispatching and recharging the battery bank, the maximum rectifier capacity, the installed solar capacity and the charge controller, to mention a few. HOMER software was also used in the post-implementation review of projects to determine the extent of variation between modeled system performance and the actual system performance.
Was ATC’s transition to renewable energy a financial or environmental decision?
There was a very strong business case for renewable energy, especially for the off-grid sites, because of the rising price of diesel fuel and the cost of delivering it to remote locations. The ultimate target was to build an off-grid site with a large enough solar PV array and battery storage that a diesel generator would not be required.
Are other companies using hybrid renewable energy systems to power their cell towers?
Yes, other cell tower companies have followed suit to install renewable energy for cell sites. While solar PV is more prevalent, some companies have also rolled out wind energy at cell sites. The attraction for renewable energy is two-fold. First the economics of deploying renewable energy to reduce diesel consumption is important. Second, using more environmentally friendly energy sources is also a significant benefit.
Nelson, you’ve told me you’re no longer designing cell tower energy systems. You’re working in the battery industry. Does that mean you’ve stopped using HOMER software?
I’m still using it! HOMER software is my go-to tool. As a consultant, I use it often to model hybrid systems for my customers.
UL Solutions’ HOMER® Pro is the leading pre-feasibility design software for modeling microgrids, with more than 250,000 users in more than 190 countries. It provides engineering and financial analyses of remote, off-grid and grid-tied complex distributed energy systems, helping reduce financial risk for owners and developers. Learn more about HOMER Pro and download a complimentary trial.