Building Sustainable IoT Energy Harvesting Solutions: A Case Study of Electronic Shelf Labels in Smart Retail
Energy harvesting ICs by Nexperia enable devices to capture and utilize ambient energy from sources like light, heat, and motion, offering sustainable and maintenance-free power solutions for a wide range of applications.
22 Apr, 2025. 7 minutes read
Internet of Things (IoT) devices are often deployed in remote or challenging environments where reliable, maintenance-free power solutions are essential. Traditional battery-dependent systems not only face limitations in such scenarios but also contribute significantly to environmental challenges. In the United States alone, it is estimated that standard portable batteries (AA, C, D, etc.) account for 20% of household hazardous material in landfills.[1] Energy harvesting offers a promising alternative to power traditional battery-reliant systems, with the potential to enable self-sustaining IoT devices.
This article explores the latest advancements in energy harvesting technology, focusing on its system design and practical applications. One of the primary areas of focus is Electronic Shelf Labels (ESLs), which showcase how energy harvesting can eliminate disposable batteries in smart retail stores. By examining the solutions and real-world use cases, we aim to provide insights into building sustainable IoT energy harvesting systems that address the limitations of current approaches and push the boundaries of what is possible.
Energy Harvesting Methods
Energy harvesting encompasses the conversion of ambient energy into electrical power, thereby reducing reliance on conventional batteries. This interdisciplinary field employs several methodologies, including:
Photovoltaic Energy Harvesting: Transforms ambient light into electricity through photovoltaic cells.
Piezoelectric Energy Harvesting: Converts mechanical stress into electrical energy using piezoelectric materials.
Thermoelectric Energy Harvesting: Exploits temperature gradients via the Seebeck effect to generate electrical power.
Electromagnetic Energy Harvesting: Utilizes Faraday’s law of electromagnetic induction to convert mechanical motion into electrical energy.
For a deeper exploration of energy harvesting, check out our previous article: Evaluating the Feasibility of Energy Harvesting for IoT Products
Energy Harvesting for ESLs: Addressing the E-Waste Problem
ESLs are digital displays used in retail environments to dynamically show pricing and product information. Widely deployed in supermarkets, ESLs offer efficiency and flexibility for updating prices in real-time. However, a major drawback of current ESL systems is their reliance on disposable batteries, which are discarded once depleted. A study suggests that soon around 78 million batteries powering IoT devices will be dumped globally every day if nothing is done to improve their lifespan.[1] This results in significant electronic waste and increases operational costs for frequent replacements.
Case Study: A Sustainable Supermarket Initiative
The environmental impact of disposable batteries in retail is substantial. A large supermarket typically deploys around 10,000 Electronic Shelf Labels (ESLs), each powered by a battery with an average lifespan of five years. This means a single store disposes of approximately 2,000 batteries annually. When scaled to a supermarket chain with 500 locations, the total number of discarded batteries reaches 1 million per year—contributing significantly to global e-waste concerns.
Beyond environmental implications, the operational costs associated with ESL maintenance are considerable. Labor costs in supermarkets are high, and when a single ESL battery fails prematurely, it is often more cost-effective for stores to replace all ESLs at once rather than conducting individual replacements. This reactive approach leads to unnecessary waste and increased expenses.
Recognizing this growing challenge, a leading supermarket chain sought a more sustainable solution. The company partnered with engineers to design and implement an energy-harvesting digital pricing system using Nexperia’s innovative energy harvesting power management ICs (PMICs). The supermarket’s primary goal was to eliminate the reliance on disposable batteries for their ESLs while maintaining seamless functionality. This approach addresses a critical limitation in battery technology, as even with 100% recycling rates, there is not enough lithium available to power the growing number of IoT devices worldwide.[1] By integrating energy harvesting techniques, the supermarket decided to take a step toward reducing its environmental footprint while ensuring reliable, long-term operation of its digital pricing systems.
Design and Testing Phase
To develop a sustainable energy-harvesting system for ESLs, the engineering team focused on designing a robust system architecture capable of eliminating disposable batteries while maintaining seamless functionality in supermarket environments. The system architecture is illustrated in the diagram below:
This design comprises the following components:
Photovoltaic Cells: Solar cells integrated into the system serve as the primary power source, effectively converting supermarket’s indoor ambient lighting into a steady and renewable energy supply.
Energy Harvesting PMIC: This module specializes in converting the captured ambient energy from the supermarket environment into stable electrical power. It operates in a harvesting power range of up to 50 mW, ensuring broad adaptability to various energy sources. Key features include ultra-fast Maximum Power Point Tracking (MPPT), which uses an embedded hill-climbing algorithm to detect maximum power points in just 0.5 seconds, optimizing efficiency in dynamic environments.
Additionally, the PMIC offers a number of battery protection features and can be configured via hard-coding or I²C, allowing for tailored solutions. The PMIC is compatible with batteries, supercapacitors, and hybrid capacitors, making it a versatile and efficient solution for sustainable IoT applications.Microcontroller: Acting as the system's control center, the microcontroller processes operational logic, including data updates for pricing and communication with external systems.
Flash Memory: Ensures data persistence during power fluctuations, enabling secure storage of pricing information and operational states.
Radio Frequency (RF) Front-End: This module facilitates wireless communication using protocols such as Bluetooth, NFC, and Wi-Fi, enabling seamless updates to pricing and product details from a central management system.
Sensors (Digital and Analog): Enhance the ESL system by enabling functionalities such as inventory tracking and monitoring environmental factors like temperature.
The design focused on achieving the following goals:
Efficient Energy Management: The PMIC, combined with Nexperia's MPPT algorithm, ensures optimal energy conversion and utilization under varying lighting conditions.
Operational Reliability: The microcontroller and flash memory guarantee uninterrupted functionality, even during brief energy dips.
Scalability and Connectivity: The RF front-end enables seamless integration with existing store systems, supporting real-time updates.
During testing, Nexperia’s evaluation board enabled the team to:
Measure indoor ambient light levels in different sections of the supermarket, ensuring photovoltaic cells could generate sufficient power consistently.
Simulate the energy demands of ESLs during peak operations, such as mass price updates, to confirm the system's ability to handle high loads.
Test the system's response to fluctuating lighting conditions, ensuring reliable performance without the need for disposable batteries.
These tests demonstrated the feasibility and robustness of the energy-harvesting design, making it ready for full-scale implementation.
Implementation Phase
Following successful testing, the supermarket chain deployed energy-harvesting ESLs across multiple store locations. Key steps in implementation included:
Fitting ESLs with Nexperia’s ICs and integrated photovoltaic cells.
Training store staff on maintaining the new system and monitoring its performance.
Collecting data on energy usage and cost savings to evaluate the system’s impact.
The new system met the sustainability goals of the supermarket and reduced operational costs associated with battery replacements and disposal.
Broader Implications
The global ESL market is projected to grow at a compound annual growth rate of 18.3% from 2024 to 2034, reaching a valuation of $1.4 billion by 2034.[2] This growth will be driven by the increasing adoption of technologies like energy harvesting, which revolutionize digital pricing systems in retail. According to a report, ESLs also enhance accuracy by reducing price errors by 5% to 10% compared to traditional paper shelf labels.[3] By integrating Nexperia’s energy harvesting technology, supermarkets can achieve greater sustainability, reduce electronic waste, and improve operational efficiency—key factors driving the broader market expansion.
Other Applications of Energy Harvesting
Energy harvesting has proven its versatility and potential across various industries. Below are some other notable applications of the technology:
In wearable technology, energy harvesting enables devices such as smartwatches, fitness trackers, and health monitors to operate with significantly extended battery life or no battery at all. By incorporating photovoltaic and kinetic energy harvesting methods, these devices reduce maintenance requirements and improve user convenience.
In IoT systems, autonomous sensors and remote monitoring solutions benefit greatly from energy harvesting. These systems, often deployed in remote locations, eliminate the need for frequent battery replacements, thereby reducing operational costs. Solar and RF energy harvesting have been successfully implemented in agricultural IoT solutions, leading to improved crop yields and optimized resource management.
Industrial operations have also adopted energy harvesting for machinery condition monitoring. Piezoelectric harvesters, for example, convert mechanical vibrations into electrical energy to power real-time diagnostics systems.
Addressing Challenges and Exploring the Future
Despite its transformative potential, energy harvesting faces several challenges:
Low Power Density: Current technologies often fall short of powering high-demand applications. Advances in material science and hybrid system architectures are addressing this limitation.
Environmental Variability: Ambient energy sources are inherently inconsistent, necessitating sophisticated storage and regulation systems.
Economic Barriers: High initial implementation costs pose significant entry barriers, though economies of scale and continuous R&D are driving cost reductions.
Nexperia’s NEH Series PMICs: Advancing Energy Harvesting Solutions
Nexperia’s energy harvesting PMICs, including the NEH71x0 series, offer cutting edge capabilities in power management for low-power applications. These modules are designed to cater to a wide range of energy harvesting requirements with flexibility and efficiency. Key features and capabilities include:
Wide Harvesting Power Range: The modules support a power range of 15 μW to 50 mW, making them suitable for various energy sources, including photovoltaic cells. They are optimized for harvesting ambient indoor light energy, enabling efficient power generation even under low-light conditions, making them ideal for indoor IoT applications like Electronic Shelf Labels (ESLs) and smart sensors.
Ultra-Fast MPPT Interval: Utilizing an embedded hill-climbing algorithm, some of the PMICs identify maximum power points within 0.5 seconds, ensuring efficiency in dynamic and fluctuating conditions.
Battery Protection Features: Integrated safeguards include Over-Voltage Protection (OVP), Low-Voltage Detection (LVD), and Over-Current Protection (OCP) to protect energy storage components.
Support for Battery-Less Designs: Cold-start functionality enables systems to operate without traditional batteries, reducing maintenance needs and electronic waste.
USB Charging and Configurable Outputs: The modules support USB charging up to 200 mA and feature a Low Dropout Regulator (LDO) with configurable output voltage for flexible designs.
Compact Form Factor: Housed in a 16-terminal Quad Flat Package (3 mm x 3 mm), these PMICs minimize external component requirements, reducing the Bill of Materials (BOM).
Inductorless Design: By eliminating the need for external inductors, these PMICs simplify circuit design, reduce overall BOM costs, and minimize complexity in compact applications.
Conclusion
Energy harvesting with Nexperia’s PMICs presents an opportunity for industries seeking sustainable and efficient power solutions for IoT devices. As demonstrated through the case study of ESLs, these ICs offer a pathway to eliminate disposable batteries and reduce electronic waste. Nexperia’s PMICs are equipped with features like ultra-fast MPPT and compatibility with various energy sources. They are enabling scalable, reliable, and cost-effective implementations across industries.
Beyond retail, energy harvesting technologies are driving advancements in wearables, IoT sensors, industrial monitoring, and automotive systems, showcasing their far-reaching potential. While challenges such as low power density and environmental variability remain, continuous innovation and research promise to bridge these gaps and unlock new possibilities.
References
[1] Mesquita R. Nexperia. Harvesting Sustainable Battery Power [Internet]. December 20, 2023. Available from: https://efficiencywins.nexperia.com/innovation/harvesting-sustainable-battery-power
[2] Pott J. Electronic shelf labels: Retailers are testing ESL [Internet]. 2024 Sep 6. Available from: https://www.euroshop-tradefair.com/en/euroshopmag/electronic-shelf-labels-retailers-are-testing-esl
[3] Zignani A. ABI Research. Electronic shelf labels in retail [Internet]. 2023 Oct 24. Available from: https://www.abiresearch.com/blogs/2023/10/24/electronic-shelf-labels-in-retail/
[4] Nexperia. Electronic Shelf Label Applications [Internet]. Available from: https://www.nexperia.com/applications/industrial-and-power/electronic-shelf-label
[5] Nexperia. Energy Harvesting Solutions: Enabling a Sustainable IoT Future [Internet]. Available from: https://assets.nexperia.com/documents/leaflet/nexperia_leaflet_energyharvesting_2025.pdf
[6] Nexperia. White Paper: Advanced Energy Harvesting for IoT Applications with Murata and Nexperia [Internet]. Available from: https://assets.nexperia.com/documents/white-paper/v06_White-paper_Murata-DT-Nexperia.pdf
[7] Nexperia. NEH7100: Energy Harvesting PMIC Data Sheet [Internet]. Available from: https://assets.nexperia.com/documents/data-sheet/NEH7100.pdf