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.

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Powering Vodafone’s Mobile Network with Solar Energy in Germany

Iberdrola has brought its first solar park in Germany into operation, with the renewable electricity generated at the site now supplying Vodafone’s mobile network nationwide. The project represents a growing convergence between energy and telecom infrastructure, as mobile operators look to secure reliable and sustainable power sources to support expanding network demands.

The solar park is located in Boldekow in the state of Mecklenburg-Western Pomerania and marks Iberdrola’s entry into onshore photovoltaic generation in the German market. The site covers an area equivalent to more than 65 football pitches and is equipped with around 80,000 solar panels. Once fully operational, the installation is expected to generate up to 53 gigawatt hours of electricity each year, with the entire output dedicated to Vodafone under a long-term power purchase agreement.

For Vodafone, the project provides a direct and predictable supply of renewable electricity for its mobile infrastructure across Germany. The annual energy output is sufficient to power around 3,000 mobile base stations, supporting the radio access network and associated systems that underpin nationwide mobile coverage. As networks continue to evolve to handle higher traffic volumes and increased densification, access to stable and locally generated energy is becoming a strategic consideration alongside spectrum, sites and backhaul.

The environmental impact of the solar park is significant. By replacing conventional grid electricity with solar generation, the project is expected to reduce carbon dioxide emissions by approximately 20,000 tonnes per year. Over an anticipated operational lifetime of around 30 years, this contributes meaningfully to emissions reduction targets while aligning network operations with wider sustainability objectives.

From an infrastructure perspective, the project illustrates a shift in how telecom operators source energy. Rather than relying solely on indirect mechanisms, such as renewable energy certificates, operators are increasingly entering direct supply agreements linked to specific generation assets. This approach improves transparency, strengthens energy security and creates a clearer relationship between network growth and renewable energy investment.

For Iberdrola, the Boldekow solar park complements its existing presence in Germany, where the company already operates offshore wind assets in the Baltic Sea. Expanding into onshore solar generation allows for a more diversified renewable portfolio and demonstrates how utility-scale energy infrastructure can be closely aligned with the needs of digital networks.

The project has also delivered local benefits, including regional investment during construction and long-term contributions to municipal revenues. This underlines how renewable energy developments tied to telecom infrastructure can support local economies while addressing national connectivity and sustainability goals.

As mobile networks progress towards higher capacity, lower latency and greater automation, their energy requirements will continue to grow. Projects such as Iberdrola’s solar park supplying Vodafone’s mobile network show how renewable energy is becoming a foundational element of modern telecom infrastructure, rather than a parallel or secondary consideration.

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NTT DOCOMO Trialled Japan’s First Self-powered Hydropower Base Station

In a move to advance sustainable telecom infrastructure, NTT DOCOMO launched a trial of Japan’s first self-powered hydropower mobile base station in May 2024. The initiative aimed to explore the viability of using flowing water from irrigation canals and similar sources to generate renewable energy for base stations, particularly in rural locations where power options are limited.

The trial featured a compact hydroelectric system based on a jet turbine co-developed with Professor Yukihiro Shimatani of the Prefectural University of Kumamoto. The turbine design integrated the nozzle and turbine into a single unit, which allowed for simplified manufacturing using 3D printing. This approach reduced both complexity and cost, making it suitable for distributed deployments in hard-to-reach areas.

The hydropower system was designed to generate electricity and convert it into a usable form for powering mobile base stations. It also collected real-time data on power output, water flow and pressure. This data was transmitted to DOCOMO’s Energy Management System platform, which monitored and controlled power distribution while visualising the reduction in CO2 emissions achieved through the system.

DOCOMO had previously relied on solar-powered green base stations to reduce its environmental impact. By March 2024, the company had deployed 286 such sites, equipped with photovoltaic panels and large storage batteries to maintain operations during grid outages. However, in areas where solar energy was not practical, DOCOMO explored alternative renewable sources, with hydropower emerging as a promising candidate.

The hydropower base station trial formed part of DOCOMO’s broader environmental commitment. The company had set out to achieve net-zero greenhouse gas emissions from its operations by 2030 and across its supply chain by 2040. With mobile base stations accounting for approximately seventy percent of DOCOMO’s energy use, the trial addressed a critical aspect of energy sustainability.

Over the one-year demonstration period, DOCOMO aimed to optimise the system’s electrical design and integration with mobile infrastructure. It also assessed which types of base stations could benefit most from hydroelectric power and how the system could be scaled for broader deployment. The company targeted March 2025 as the timeline for evaluating results and considering next steps.

This trial represented more than just an engineering exercise. It reflected a growing focus within the telecoms sector on decarbonisation, resilience and innovation. By experimenting with alternative renewable energy sources, DOCOMO showed how network operators could adapt infrastructure for a lower-carbon future, while improving coverage and reliability in off-grid areas.

As telecom networks continue to expand, projects like this highlighted the importance of flexible, locally sourced power solutions in shaping a sustainable infrastructure roadmap.

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