The growth of renewable energy for mobile towers: The role of eco-system players and innovative technology

At the end of 2020 GSMA CleanTech published ‘Renewable Energy for Mobile Towers’, a report that examined the current state of the mobile tower industry, how it has changed over recent years, and the barriers that still need to be overcome before the majority of off-grid and bad-grid towers can be run on renewable energy. While revealing some positive trends, the report also highlighted the opportunity to reduce the 2.2 million metric tons of CO2 emitted from diesel generators at off-grid and bad-grid towers annually. The findings of the report are summarised in a short video which can be viewed here

This blog is first of a series to highlight examples of technical innovation and pioneering work being done across the industry. We will examine the role of four stakeholder groups: eco-system players, mobile network operators, tower companies and energy service providers in driving greater use of renewable energy for mobile towers. In this first blog, we look at the role of a critical group of organisations we dub ‘eco-system players’. The technology and deployments referenced for this first blog come from representatives of Ericsson, Huawei and ZTE, who kindly shared examples of how they support the industry adopt renewable energy.

Sites with limited space or shading are unsuitable for solar

The last decade has witnessed a remarkable series of innovations that together have genuinely transformed the ways in which renewable energy can be used to power, operate and protect mobile towers. Previously many areas were considered unsuitable for photovoltaic (PV) panels, particularly if the sites offered limited space or were in shade. However, new PV optimiser technology, such as Huawei’s iPV products, allows solar panels connected in series (one after another) to communicate through power line communication technology and automatically vary voltage and current to ensure they supply their maximum power consistently. This reduces the effect of shading on adjacent panels by up to 67 per cent, and also allows greater flexibility in the number of panels that can be used. Deployments of this technology in Europe and Asia have facilitated power demands for a 2.5kW site to be met with 24 per cent less space than would have been expected using non-optimised panels. In Pakistan ZTE, for example, has retrofitted over 200 sites with solar equipment with no site expansions; these sites have subsequently seen an 80 per cent saving in diesel fuel costs. 

Extreme environmental conditions make renewable solutions unsuitable

In the past renewable energy systems also struggled to cope with extreme temperatures in comparison with their diesel counterparts. Following dramatic improvements in battery technology, battery chemistries now offer much greater temperature tolerances. Using its Heat Proof and High Loop batteries, ZTE has successfully deployed solar-battery hybrid solutions at very low temperatures in altitudes of more than 5000m in Nepal and solar-diesel-battery systems in South Sudan, where temperatures can reach 40C. In doing so, ZTE has convincingly shown that battery systems can work in challenging thermal environments. 

ZTE deployment on Mount Everest, Nepal at 5,180m elevation. Extremely difficult site access meant that a low maintenance solar-battery hybrid system architecture was optimal.

Using multiple power sources creates energy management challenges

Despite their negative environmental impact, diesel generators have long been seen as an extremely reliable alternative source of power wherever grid power is unavailable or interrupted. Recent advances in connectivity and remote data management, however, are allowing new energy management systems, such as iEnergy (ZTE), NetEco (Huawei) and Ericsson Network Manager, to manage hybrid energy systems much more efficiently. By processing data about battery state-of-charge and solar irradiation, among many other variables, cloud-based software that harnesses artificial intelligence data-processing techniques can provide intelligent, actionable insights that help operators optimise power generation and energy use. In turn, this helps to preserve the longevity of the equipment, minimise energy costs and ensure uninterrupted power supply to the radio equipment. For grid-connected systems, remote intelligence is now able to optimise grid demand based on electricity rates, minimising the power drawn at higher rate times and also cut peak power demand (peak shaving), thereby minimising costs. Successful recent examples of remote data management include a 13kWp solar-diesel hybrid system set up by Ericsson in Bolivia and a 6kWp solar-diesel hybrid rolled out by Huawei in Ethiopia. Ericsson’s Enclosure 6150 product with solar add-on rack offers both existing and greenfield sites the ability to add up to 10kWp of solar power, seamlessly managing the additional power source in both on- and off-grid applications. 

The variability of wind and solar irradiation mean that renewables are not able to provide consistent power

Huawei solar-diesel hybrid system in Ethiopia. The addition of solar is estimated to be mitigating 26 tons equivalent CO2 emissions annually.

Importantly, weather data can also be fed into the management systems to allow them to predict and optimise energy flows. Predictive analysis means that the power management parameters of towers can vary each day according to local weather conditions, saving money. For example, the system can switch off a diesel generator or stop drawing power from the grid based on predictions of the weather and the site load. This allows the battery to discharge more energy at night and store more solar generated energy. This therefore decreases the system’s reliance on diesel and the grid. Huawei’s implementation of solar-diesel hybrid systems in Somalia, replacing diesel-only power, has been able to achieve a return on investment in less than three years after the systems were installed. 

System faults need to be diagnosed and fixed with a site visit

A further benefit of these new monitoring systems is that they permit operators to identify faults remotely. This allows operators to reduce the number of site visits, address faults more quickly, and conduct pre-emptive maintenance. The combined result is, of course, lower operational costs and reduced system down-time. In Tanzania, for example, Ericsson has deployed pure solar, off-grid systems using their Enclosure 6135 product, which has a 20kW solar converter capacity. Since Ericsson’s monitoring platform combines data from the passive equipment such as the batteries and active site equipment such the radio communication equipment it’s possible to view site-wide information on a single platform. This offers real-time remote control of all assets which improves site security, minimises energy and system lifecycle costs and allows for precise and proactive maintenance of all the site’s equipment.  

Equipment theft

Ericsson deployment of a pure solar site in Tanzania using Enclosure 6135.

Finally, the continued digitalisation of mobile tower power systems is unlocking the capacity of technology to reduce a major problem faced by many remote mobile towers: theft of assets. Huawei’s NetEco monitoring system can allow the tracking of GPS-embedded equipment including Li-ion batteries, while software enables stolen equipment to shut down if connected to an unregistered device. Furthermore, accelerometers and gyroscopes can detect if equipment is being moved unexpectedly and trigger an alarm. ZTE’s intelligent SmartLi Li-ion batteries have been used to great effect for deployments in Pakistan, where over 11,000 SmartLi batteries were deployed, including at sites operating lead-acid batteries in conjunction. In Libya, sites deployed with SmartLi have been able to address a persistent battery theft problem, increase network availability and produce an estimated 30 per cent reduction in total cost of ownership of the sites, considering a 10 year period. 

Over the past decade, technical challenges have been sighted as a reason not to adopt renewable energy. However, using innovative solutions and advanced technology it has become possible to overcome these challenges and now, even at the most difficult of sites, it is technically viable to implement renewable energy solutions. Looking forward, these eco-system players seem set to continue to increase the range of renewable energy solutions they offer. With a 100 per cent renewable source company vision, Ericsson, for example, is set to deploy in 2021 wind power solutions to complement solar generation and Li-ion storage as part of its latest generation of equipment (Enclosure 6140), paving the way for growth in this area. Ericsson is also currently trialling small site footprint, easy installation, pico-solar solutions, which may prove an important technology to help connect remote, off-grid rural areas.

In our next blog we will continue this theme and showcase examples of what mobile network operators are doing to transition to more sustainable ways of powering mobile towers.  

If you would like to hear more about the solutions mentioned here, please reach out to us to find out more. 

This initiative is currently funded by the UK Foreign, Commonwealth & Development Office (FCDO), and supported by the GSMA and its members.
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