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Introduction
In distributed photovoltaic, household photovoltaic, and remote off grid photovoltaic systems, current sensors often face the practical dilemma of “limited power supply” – some combiner boxes and monitoring terminals rely on solar panels for auxiliary power supply or energy storage batteries for power supply, which puts strict requirements on the power consumption of sensors. Data shows that the working power consumption of traditional current sensors is mostly between 100-200mW, accounting for 30% -40% of the total power consumption of small monitoring terminals. This not only exacerbates the discharge pressure of energy storage batteries, but also may lead to frequent offline of sensors due to insufficient power supply, affecting the continuity of data acquisition. With the development of photovoltaic systems towards “unmanned and long-term operation”, low power consumption has become the core technical indicator of current sensors, and its energy-saving design directly affects the endurance and operation and maintenance costs of photovoltaic monitoring systems.
1、The core demands of low-power scenarios and the shortcomings of traditional technologies
The demand for current sensors in low-power photovoltaic scenarios presents the characteristics of “balancing low consumption and high performance”:
From the perspective of power supply conditions, the energy storage battery capacity of household photovoltaic monitoring terminals is usually only 10-20Ah, which needs to support the continuous operation of sensors for 3-6 months without replenishment; The auxiliary power supply module of off grid photovoltaic systems in remote areas has limited power, and every 50mW reduction in sensor power consumption can free up power supply surplus for other monitoring equipment. Meanwhile, low power consumption cannot be achieved at the expense of performance – sensors still need to maintain measurement accuracy within 0.5% and a response speed of 1 μ s to meet MPPT control and fault monitoring requirements.
The low-power adaptation capability of traditional current sensors is significantly insufficient: on the one hand, sensors using traditional Hall elements have a high power consumption ratio between the driving circuit and signal amplification circuit, with static power consumption generally exceeding 80mW, making it difficult to adapt to power limited scenarios; On the other hand, some products simply reduce circuit functions to reduce power consumption, resulting in decreased accuracy and weakened anti-interference ability. In low light and low-power mode, measurement errors may expand to over 2%. According to data from a household photovoltaic project, when using traditional high-power sensors, the energy storage battery of the monitoring terminal needs to be charged every 2 months, and the missing rate of power generation data caused by offline sensors is 5% -8%.
2、 The core optimization path of low-power technology
In response to the demand for low-power photovoltaic scenarios, current sensors have achieved energy-saving breakthroughs through three major technological directions: material innovation, circuit optimization, and intelligent sleep
In the selection of sensitive components, low-power giant magnetoresistance (GMR) and tunneling magnetoresistance (TMR) chips are used to replace traditional Hall elements. These new types of components do not require complex driving circuits, and the static operating current can be reduced from 10-20mA of traditional Hall elements to 1-3mA. The overall static power consumption of the sensor can be controlled within 30mW, which is more than 70% lower than traditional products. At the same time, the low power consumption characteristics of the new components will not affect measurement accuracy, and can still maintain a full range accuracy of 0.3% over a wide temperature range.
In terms of circuit design, the “integration+low-power device” solution is adopted: signal processing, isolation, and output modules are integrated into dedicated ASIC chips to reduce power consumption losses of discrete components; Select low-power operational amplifiers and ADC chips (operating current ≤ 100 μ A), optimize the power management circuit, achieve wide range adaptation of power supply voltage (3.3V-12V), and be compatible with different types of auxiliary power supply modules. Some high-end products also introduce energy recovery design, which collects weak magnetic field energy from current signals to provide auxiliary power for sensors, further reducing dependence on external power sources.
In terms of working mode optimization, an intelligent sleep algorithm is embedded: the sensor operates in low-power monitoring mode by default. When the current signal is stable and there are no abnormal fluctuations, the sampling frequency is automatically reduced (from 1kHz to 100Hz), further reducing power consumption by 50%; When abnormal situations such as sudden changes in current or overcurrent are detected, immediately wake up to high-speed sampling mode to ensure that the fault signal is not lost. This “on-demand allocation of computing power” design can maximize battery life without affecting monitoring reliability.
3、 Actual application effect and industry value
The implementation of low-power technology has achieved significant results: after adopting low-power current sensors in a distributed photovoltaic project, the battery life of the monitoring terminal’s energy storage battery has been extended from 2 months to 8 months, the annual operation and maintenance charging times have been reduced from 6 times to 1-2 times, and the operation and maintenance costs have been reduced by more than 60%; The offline rate of sensors has decreased from 7% to 1.2%, significantly improving the integrity of power generation data. For off grid photovoltaic systems in remote areas, low-power sensors can be directly powered by components without the need for additional high-capacity energy storage batteries, reducing the hardware cost of a single system by 15% -20%.
In addition, low-power design can also reduce the self heating of sensors, reduce the impact of heat accumulation on accuracy in compact spaces (such as micro combiner boxes), and control the accuracy drift within a wide temperature range within 0.2%, indirectly improving the long-term operational stability of the system.
Conclusion
The power supply limitations in low-power photovoltaic scenarios are driving the transformation of current sensors from “performance first” to “balancing performance and low consumption”. The high power consumption shortcoming of traditional sensors has become a key factor restricting the long-term operation of distributed, household, and off grid photovoltaic systems; Through the collaborative innovation of new sensitive material applications, circuit integration optimization, and intelligent sleep algorithms, current sensors have achieved the unity of “low power consumption, high precision, and long endurance”. This technological evolution not only solves the practical pain points of power supply limited scenarios, but also aligns with the development concept of “cost reduction, efficiency improvement, green and low-carbon” in the photovoltaic industry. In the future, with further iteration of low-power technology, current sensors will provide more flexible and reliable technical support for the full field adaptation of photovoltaic systems.
