Solar Energy Complementary Solution for High-Frequency UPS in Rural Base Stations
Solar Energy Complementary Solution for High-Frequency UPS in Rural Base Stations
Rural base stations are the cornerstone of digital rural construction, but they often face challenges such as unstable commercial power supply, high power supply costs, difficult cable laying, and harsh operating environments (extreme temperatures, dust, and thunderstorms). High-frequency UPS (Uninterruptible Power Supply) is widely used in rural base stations due to its fast switching speed, high efficiency, and compact size. However, relying solely on commercial power and UPS battery backup cannot fundamentally solve the problems of high energy consumption and poor continuity in off-grid scenarios. The solar energy complementary solution for high-frequency UPS integrates solar photovoltaic (PV) systems, energy storage batteries, and intelligent control modules, forming a "commercial power + solar energy + UPS" triple power supply guarantee. This solution not only reduces the operation and maintenance costs of rural base stations but also improves the stability and reliability of power supply, effectively addressing the pain points of power supply in remote rural areas. This article elaborates on the system composition, working principle, core design points, and rural scenario adaptation strategies of this complementary solution.
1. System Composition and Core Components
The solar energy complementary system for high-frequency UPS in rural base stations is a integrated energy supply system consisting of five core parts: high-frequency UPS host, solar PV array, energy storage lithium battery pack, MPPT charge controller, and intelligent monitoring system. Each component undertakes a unique function and collaborates to ensure stable power supply for base station equipment.
1.1 High-Frequency UPS Host
As the core power conversion and switching device of the system, the high-frequency UPS adopts a modular design with a conversion efficiency of over 95%, which is 3%-5% higher than traditional low-frequency UPS. It supports millisecond-level switching between commercial power and backup power, ensuring that base station equipment (transceivers, signal amplifiers, and monitoring devices) is not interrupted during power outages. For rural base stations, the UPS should be selected according to the actual power consumption: a single 5G outdoor base station has an average power consumption of about 4kW, which is three times that of 4G base stations, so a 5-10kW high-frequency UPS with redundant capacity is recommended to cope with short-term power surges.
In addition, the UPS needs to have good compatibility with solar energy systems and lithium batteries, supporting flexible switching between grid-tied and off-grid modes. It should also integrate multiple protection functions such as overvoltage, undervoltage, overcurrent, and overheating to adapt to the large voltage fluctuations of rural power grids.
1.2 Solar PV Array
The PV array is the energy collection terminal of the system, responsible for converting solar energy into direct current (DC) power. Considering the harsh outdoor environment of rural base stations, high-efficiency monocrystalline silicon solar panels are preferred, which have a photoelectric conversion efficiency of over 23% and excellent performance in low-light conditions (such as morning fog and cloudy days in rural areas). The installation capacity of the array is determined by the base station's daily power consumption and local solar radiation conditions: for a 4kW 5G base station with an average daily power consumption of 60kWh, a 15-20kW PV array is usually configured in areas with sufficient sunlight (such as the northwest countryside), while a 20-25kW array is required in areas with low solar radiation (such as the southern mountainous countryside).
The installation method should adapt to rural terrain and land use characteristics. Referring to the successful case of the Zaha Highway base station in Qinghai, the "guyed mast + PV panel" installation method can be adopted, which not only saves land resources but also avoids damage to the ecological environment, facilitating the approval of construction land in ecological protection areas .
1.3 Energy Storage Lithium Battery Pack
The battery pack serves as the energy storage and backup unit of the system, storing surplus solar energy during the day and providing power for the UPS when commercial power is interrupted or solar energy is insufficient. Lithium iron phosphate batteries are the preferred choice for rural base stations due to their long cycle life (over 3000 cycles), high safety, and good temperature adaptability. The capacity configuration should ensure that the base station can operate continuously for 8-12 hours under full load when both commercial power and solar energy are cut off (such as continuous rainy days).
It should be noted that lithium batteries are sensitive to temperature. In rural areas with low temperatures (such as northern China), the battery's chemical activity decreases significantly, leading to reduced available capacity and increased internal resistance . Therefore, the battery pack needs to be equipped with a thermal insulation module and a temperature control system to maintain the operating temperature between 10°C and 35°C, avoiding permanent damage caused by low-temperature charging and discharging.
1.4 MPPT Charge Controller
The Maximum Power Point Tracking (MPPT) controller is the link between the PV array and the battery pack, responsible for maximizing the efficiency of solar energy collection. It dynamically adjusts the working voltage and current of the PV array according to changes in light intensity and temperature, improving the energy utilization rate of the array by 15%-20% compared to traditional PWM controllers. For rural base stations with uneven light conditions (such as shading by crops and trees), a dual-channel MPPT controller is recommended to independently track the maximum power point of two groups of PV panels, reducing the impact of partial shading on the entire system.
1.5 Intelligent Monitoring System
The intelligent monitoring system realizes centralized management and remote maintenance of the entire complementary system, which is crucial for rural base stations with scattered locations and difficult on-site maintenance. The system integrates 4G/WiFi communication modules, supporting real-time monitoring of PV power generation, battery state of charge (SOC), UPS operating parameters, and base station load through a cloud platform. It can automatically send fault alarms (such as PV panel damage, battery overheating, and UPS failure) to maintenance personnel via mobile apps, reducing troubleshooting time.
For village-level centralized base station projects, the system also supports unified management of multiple stations, realizing batch parameter setting and data statistics, further reducing operation and maintenance costs.
2. Working Principle and Operating Modes
The solar energy complementary system for high-frequency UPS operates in a coordinated manner through intelligent control, adapting to different power supply conditions and load demands, and ensuring continuous and stable power supply for rural base stations. The system mainly has three operating modes:
2.1 Grid-Tied Mode (Commercial Power Normal)
When commercial power is stable, the system operates in grid-tied mode. Commercial power supplies power to the base station load through the high-frequency UPS, and the UPS charges the energy storage battery pack with a constant current and constant voltage. At the same time, the PV array converts solar energy into DC power, which is converted into stable DC power by the MPPT controller to charge the battery pack or directly supply power to the UPS's DC side. When the battery pack is fully charged, the excess solar power is fed back to the rural power grid (if permitted by local policies) or consumed by adjusting the base station's auxiliary load, avoiding energy waste.
This mode can reduce the reliance on commercial power, lower the base station's annual electricity bill by 20% or more, and achieve the goal of green energy conservation .
2.2 Off-Grid Mode (Commercial Power Interrupted)
When commercial power is interrupted (a common situation in remote rural areas due to line failures or extreme weather), the high-frequency UPS switches to off-grid mode within milliseconds, and the energy storage battery pack and PV array jointly supply power to the base station. The PV array provides real-time power according to light conditions, and the battery pack supplements the power gap to ensure that the load voltage and frequency are stable within the allowable range. If the light intensity is insufficient (such as at night or on cloudy days), the battery pack becomes the main power source, and the system automatically adjusts the base station's non-critical load (such as auxiliary lighting) to extend the battery's backup time.
2.3 Emergency Backup Mode (Extreme Conditions)
In extreme conditions such as continuous rainy days (solar energy shortage) and long-term commercial power outages, the system can be connected to an optional diesel generator as an emergency backup power source. The intelligent controller automatically starts the diesel generator when the battery SOC is lower than 20%, charges the battery pack and supplies power to the load, ensuring that the base station does not stop working due to energy exhaustion. This mode is especially suitable for remote rural areas with poor power grid conditions.
3. Core Design Points for Rural Scenario Adaptation
Rural base stations have unique characteristics such as weak power grid foundation, harsh natural environment, and difficult maintenance. The solar energy complementary solution must be optimized for these characteristics to ensure practicality and reliability.
3.1 Power Grid Adaptation Design
Rural power grids often have problems such as long transmission lines, small capacity, and large voltage fluctuations. The high-frequency UPS should support a wide voltage input range (220V±15% for single-phase, 380V±10% for three-phase) and frequency adaptation (50Hz±2Hz), avoiding frequent shutdowns due to power grid abnormalities. For areas with serious reactive power loss, the UPS should integrate a reactive power compensation function to improve the power factor of the system and reduce the impact on the rural power grid.
3.2 Environmental Protection Design
Rural base stations are mostly located outdoors, facing challenges such as high temperature, dust, thunderstorms, and rodent damage. The system components should meet high protection standards: the UPS and MPPT controller adopt IP65 protection level, effectively preventing dust and rainwater intrusion; the PV panel surface is coated with anti-reflective and anti-dust film, reducing the impact of agricultural residues and bird droppings; the cable adopts rodent-proof and anti-corrosion materials to avoid damage in farmland environments . In thunderstorm-prone areas, an integrated lightning protection device (with a lightning protection level of 20kA or more) should be installed to protect the entire system from lightning surges.
3.3 Low-Temperature Adaptation Design
In northern rural areas with low temperatures, the performance of lithium batteries and PV panels is significantly affected. In addition to the battery thermal insulation system, the PV array should be installed at an optimal angle (30°-45°) to increase solar radiation reception in winter. The charging strategy of the MPPT controller should be adjusted in low-temperature environments, reducing the charging current to avoid lithium precipitation on the battery electrode, which causes permanent damage . The UPS's internal cooling system should adopt an intelligent temperature control fan to ensure normal operation at -20°C to 60°C.
3.4 Cost-Optimized Design
Rural base station projects often have limited budgets. The solution should balance initial investment and long-term operation costs: select cost-effective PV panels and lithium batteries to avoid over-configuration; adopt modular design for UPS and controllers, facilitating later capacity expansion without replacing the entire system; use the "one-send dual-receive" communication technology to reduce the cost of data transmission and monitoring . Through reasonable design, the investment recovery period of the system can be controlled within 3-5 years.
4. Operation and Maintenance Strategies for Rural Base Stations
The operation and maintenance level of rural base stations is relatively low, so the complementary system should be designed to be easy to maintain, reducing the dependence on professional personnel.
4.1 Regular Maintenance Measures
Clean the PV panels quarterly to remove dust, agricultural residues, and bird droppings, ensuring photoelectric conversion efficiency. In areas with heavy sandstorms, the cleaning frequency can be increased to once a month.
Inspect the battery pack every six months, check the connection terminals for looseness and corrosion, and test the SOC and cycle life. Replace aging batteries in a timely manner to avoid affecting the backup capacity.
Clean the cooling vents and fans of the UPS and controller regularly to prevent overheating caused by dust accumulation. Check the lightning protection device before the thunderstorm season and replace damaged components.
4.2 Remote Maintenance and Fault Handling
Make full use of the intelligent monitoring system to realize remote diagnosis and troubleshooting. For common faults (such as PV panel shading, battery under-voltage, and communication failure), maintenance personnel can guide rural operators to solve them through the mobile app, avoiding on-site maintenance in remote areas. For complex faults (such as UPS power module damage), the system can automatically locate the fault point and send a detailed alarm message to after-sales personnel, shortening the maintenance cycle.
4.3 Low-Temperature Operation Precautions
In winter, avoid charging the battery pack in low-temperature environments (below 0°C). If the base station is in an extremely cold area, the battery cabinet can be equipped with a heating device powered by solar energy. When the battery is frozen and cannot discharge normally, move it to a warm environment to thaw naturally before use, avoiding forced charging and discharging .
5. Application Cases and Practical Effects
The solar energy complementary solution for high-frequency UPS has been widely applied in rural base station projects across the country, achieving remarkable economic and social benefits.
In the Zaha Highway base station project in Qinghai, the "guyed mast + solar energy + lithium battery + high-frequency UPS" solution was adopted due to the harsh environment, long cable laying distance, and high cost . The project configured a 18kW PV array and a 100kWh lithium battery pack, cooperating with a 10kW high-frequency UPS. After commissioning, the base station's annual electricity bill was reduced by more than 25,000 yuan, and the power supply continuity rate reached 99.9%. Even in extreme weather such as heavy snow and strong winds, the base station can operate stably, effectively solving the problem of no signal along the highway.
Xingtai Mobile adopted a solar PV power supply + integrated energy cabinet + high-frequency UPS hybrid power supply system for rural 5G base stations . The system realizes the coordinated operation of commercial power, solar energy, and batteries, reducing the single-station energy consumption by more than 20%. It not only meets the increasing power demand of 5G base stations but also achieves the goal of green development, providing a replicable model for rural base station energy supply.
Conclusion
The solar energy complementary solution for high-frequency UPS effectively solves the problems of unstable power supply, high cost, and poor environmental adaptability of rural base stations by integrating solar energy, energy storage, and UPS technology. Its reasonable system composition, flexible operating modes, and rural-oriented optimization design not only ensure the continuous and stable operation of base station equipment but also reduce energy consumption and operation and maintenance costs, contributing to the construction of digital and green rural areas.
With the in-depth advancement of rural revitalization and the popularization of 5G networks, the demand for reliable power supply in rural base stations will continue to grow. The solar energy complementary solution will be further optimized in terms of efficiency, cost, and intelligence, such as integrating artificial intelligence to predict solar energy generation and adjust load distribution, and adopting more efficient energy storage materials to improve battery performance. It will become an indispensable core support for the sustainable development of rural communication networks.
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