How NTT DOCOMO and PLDT Are Making Solar-Powered Base Stations Smarter

Solar-powered mobile base stations are not new, but making the most of the electricity they generate remains a challenge. Solar generation varies throughout the day and depends on weather conditions, while mobile networks need a continuous and reliable electricity supply. Batteries can help bridge this gap, but their capacity must also be reserved to keep networks running during power outages.

In September 2026, NTT DOCOMO announced the successful demonstration of its weather-forecast-linked lithium-ion battery control technology in the Philippines, working with PLDT and its mobile subsidiary Smart Communications. The trial marked the first overseas deployment of a technology that DOCOMO originally developed in Japan in 2016.

The demonstration involved two green base stations operating under different conditions. One was located near Metro Manila, where grid electricity was available, while the second was an off-grid site on Cebu Island. Both incorporated solar panels, battery storage and DOCOMO's Energy Management System (EMS) platform, which manages electricity generation, storage and consumption.

What makes the technology interesting is how it manages the batteries. Traditionally, a significant proportion of battery capacity at mobile sites is reserved for emergency backup. While this helps maintain connectivity during electricity outages, it also limits how much surplus solar electricity can be stored and used during normal operations.

DOCOMO's approach uses weather forecasts and expected electricity demand to dynamically adjust the proportion of battery capacity allocated to backup and everyday energy management. When conditions permit, more capacity can be used to store and supply solar-generated electricity, while sufficient reserves must still be maintained to support network operations during outages. The control algorithms were also adapted to reflect local climate and electricity supply conditions in the Philippines.

The results were encouraging. Solar power utilisation efficiency increased from 38% to 61%, an improvement of 23 percentage points. The battery systems also enabled the effective use of 3,905 kWh of surplus solar electricity that would otherwise have gone unused. According to DOCOMO, the demonstration reduced cumulative CO₂ emissions by approximately 2,854 kg during a 100-day validation period between April and July 2026.

DOCOMO already has considerable experience with renewable-powered infrastructure, having deployed 329 green base stations across Japan by the end of March 2026. These installations form part of its wider efforts to reduce network energy consumption and improve resilience. The company has also explored alternative renewable sources, including a self-powered hydropower base station that we previously covered.

From an infrastructure perspective, the Philippine demonstration is particularly relevant because energy availability and reliability can vary significantly between locations. Grid-connected sites may benefit from lower electricity consumption and costs, while remote or off-grid sites can potentially make better use of locally generated renewable energy. Intelligent battery management could also help operators balance energy efficiency with the need to maintain communications during extended power disruptions.

There are still questions around large-scale deployment, including installation costs, battery ageing, forecast accuracy and the amount of backup capacity that can be guaranteed under different operating conditions. The published results do not provide a site-by-site breakdown or quantify the impact on battery lifetime and outage performance.

Nevertheless, the demonstration highlights an important evolution in telecom infrastructure. Making mobile networks more sustainable is not simply about installing solar panels or larger batteries. Increasingly, it is about intelligently managing the energy already available, balancing cost, sustainability and resilience to keep networks operating reliably.

Related Posts: 

• Telecoms Infrastructure Blog: NTT DOCOMO Trialled Japan’s First Self-powered Hydropower Base Station
• Telecoms Infrastructure Blog: Electric Vehicles as a Resilient Power Source for Telecom Infrastructure 

How Vodafone UK Prepares its Network for Storms and Heatwaves

Extreme weather is a growing concern for mobile network operators, and Vodafone is no exception. Storms and heatwaves can damage infrastructure, interrupt power supply, and delay repair work. To keep people connected during such events, Vodafone has developed a range of technical measures and operational strategies that help it prepare for and respond to disruption.

The most exposed part of the network is the mast, which is usually above ground and can be up to 25 metres tall. While it is not possible to make these completely immune to bad weather, Vodafone designs them with resilience in mind. Many mast sites are equipped with backup batteries and generator connection points, provided there is space to install them safely.

Vodafone operates around 18,000 masts across the UK. Each one is part of the wider Radio Access Network, with traffic routed through dedicated signalling controllers hosted in secure data centres. These centres are equipped to maintain at least one mobile service, even in the event of a power outage, by prioritising the use of backup power.

In rural areas, some masts rely on microwave links instead of fibre or copper connections. These links require a clear line of sight between masts, so engineers carry out preventative maintenance to remove any vegetation that might interfere with signal transmission.

The Network Operations Centre (NOC) monitors the network and directs field engineers. During weather alerts, Vodafone increases staffing levels to improve response times and ensure the right resources are in place. Temperature sensors at mast sites detect heat-related issues and automatically alert the NOC if thresholds are exceeded. This can lead to quick interventions, such as cleaning or replacing clogged air filters in cooling systems.

If a mast repeatedly shows signs of overheating, the NOC flags it for further investigation. Possible solutions include enhanced maintenance schedules or upgrading the cooling technology. Despite all these precautions, access and repair work after storms or floods can still be complicated by damaged roads or infrastructure. Engineers may need to assess fibre cables, antennas or even the structural integrity of masts.

Where power supply is disrupted for extended periods, Vodafone’s network planners must carefully manage the use of batteries and generators. Coordination with external bodies such as the National Grid is often essential.

By investing in resilient infrastructure and ensuring rapid response capabilities, Vodafone aims to keep its mobile network running reliably, even in the face of increasingly unpredictable weather.

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• Telecoms Infrastructure Blog: Vodafone Explains Mobile Phone Mast
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• The 3G4G Blog: What is meant by Infrastructure in a Telecoms Network?
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Electric Vehicles as a Resilient Power Source for Telecom Infrastructure

In an era where reliable telecommunications infrastructure was critical, Japan’s telecom giant NTT DOCOMO, in collaboration with NTT Corporation and Nippon Car Solutions (NCS), launched a ground-breaking demonstration experiment to enhance base station power resilience during outages. This initiative explored the feasibility of using electric vehicles (EVs) as mobile power sources, supported by AI-driven dispatch planning.

Addressing the Challenge of Power Outages

Telecom networks rely on consistent power to maintain connectivity, especially during emergencies. Traditionally, base stations depend on backup batteries with limited capacity, supplemented by generators in prolonged outages. However, with the increasing adoption of EVs, their potential as mobile energy sources offered a novel and sustainable approach to bolstering telecom infrastructure resilience.

The experiment integrated multiple technological components:

• DOCOMO’s Energy Management System (EMS): This platform monitored the charge status of base stations and coordinated power-sharing between EVs and telecom infrastructure.
• NTT’s AI-Based Dispatch Planning: Leveraging deep reinforcement learning, this system dynamically optimised EV dispatch to ensure timely power delivery to affected base stations.
• Real-time EV Data Collection: Provided by NCS, this component tracked EV location, stored power, and driving data to enhance operational efficiency.

A Smart, AI-Driven Approach

One of the key innovations in this experiment was the use of AI-driven route planning to deploy EVs effectively. The AI system not only determined the fastest routes for EVs to reach power-downed base stations before backup batteries depleted but also ensured that vehicles were directed to charging stations before their own power ran low. By optimising travel and energy allocation, the AI model addressed logistical challenges that could otherwise hinder the feasibility of EV-based power support.

The trial, conducted in Chiba Prefecture, simulated wide-area power outages and assessed the effectiveness of the AI dispatch model in real-world conditions. By driving EVs according to AI-generated plans and measuring the charging effectiveness at base stations, the experiment aimed to refine this approach for broader adoption.

Sustainable and Scalable Solutions for Future Telecom Networks

Beyond immediate disaster response, this initiative aligned with broader sustainability goals. As a member of the EV100 initiative, NTT was committed to accelerating the adoption of electric vehicles within corporate fleets. Integrating EVs into telecom infrastructure resilience strategies not only enhanced disaster response but also contributed to reducing carbon footprints in the industry.

If successful, this model could be used as a blueprint for telecom operators worldwide, particularly in regions prone to natural disasters. By leveraging AI, energy management systems, and EV technology, telecom networks could build a more resilient, flexible, and sustainable power backup strategy.

This forward-thinking trial underscored how emerging technologies could be harnessed to address infrastructure vulnerabilities, ensuring uninterrupted connectivity when it mattered most. As the telecom industry continued to evolve, integrating intelligent, sustainable power solutions remained key to enhancing network reliability and disaster preparedness.

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• Telecoms Infrastructure Blog: NTT Docomo's Cell On Wheels (COW)
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KDDI's Power Backup Solutions

Over the last few years you might have read multiple blog posts on our blogs (see related posts below) about how KDDI is preparing for disasters by having all kinds of backup solutions. In the last six months they have taken this even further by taking about their bendable solar cells and lighter backup batteries.

In some situations the base stations have to be installed at locations where it is not possible to deploy solar cells for power. In these locations, KDDI is working with partners to use next generation "perovskite" solar cells which are thin, light and flexible so it can be wrapped around the poles and generate a reasonable power all day long. 

Here is a video (no subtitles, but none needed):

You can learn more about this here.

Another innovation being tested by KDDI is the use of zinc secondary batteries to strengthen power outage countermeasures during disasters. While backup power supply equipment is effective as a countermeasure against long-term power outages during disasters, the problem is that it cannot be installed or expanded due to the load capacity of the building. 

Quoting from the Google translated article:

Zinc secondary batteries are approximately 50% lighter than the lead-acid batteries used in many base stations, allowing for more space to be installed, while having twice the capacity for the same size, extending base station operating time. This can be extended up to 72 hours. 

At base stations, there is an urgent need to install or expand large-capacity backup power supply equipment as a countermeasure against long-term power outages such as during disasters. Zinc secondary batteries are lightweight, allowing more space for installation, and are the same size as lead-acid batteries, allowing base stations to operate for long periods of time, so they are expected to contribute to maintaining communications during disasters. In addition, since it does not contain harmful lead and there is no risk of heat generation, installation work can be simplified, and it is expected to contribute to the acceleration of the expansion of 5G areas.

In this demonstration, we plan to operate a base station that uses zinc secondary batteries as backup power supply equipment in a real environment for one year, confirming its operation through seasonal changes in temperature and humidity, and conducting power outage tests.

Looking forward to hearing about the results of both these initiatives.

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• Connectivity Technology Blog: KDDI Prepares for Disasters with Vehicle-Mounted Base Stations Backhauled via Starlink
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