Dynamic PV String Voltage Management for Solar Efficiency
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Solution Overview
Problem
Solar power systems are underperforming due to conservative electrical codes that limit PV string voltage based on the lowest historical ambient temperature, which does not represent real-world operating conditions, leading to inefficiencies in energy harvesting.
Innovation Solution
Implementing an active system design that dynamically manages voltage and current by selecting the number of PV modules and bypass modules to optimize target string voltage, temporarily disconnecting modules when necessary to prevent exceeding maximum regulatory voltage, thereby maintaining safety and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the solar power system is designed in accordance with NEC section 690.7 to limit PV string voltage based on the lowest expected ambient temperature, then the system operates within electrical code safety requirements, but the string voltage is limited which lowers efficiencies of the solar power system
Solution Approach 1:
The patent implements a dynamic voltage management system that actively adjusts the PV string voltage based on real-time environmental conditions (temperature, irradiance) rather than using a static conservative design. The system includes a controller that monitors ambient temperature and irradiance levels, and dynamically reconfigures the PV string by connecting or disconnecting modules to optimize voltage for current conditions while remaining within safe operating limits defined by the electrical code.
Solution Approach 2:
The system changes the operating parameters (voltage, current, module configuration) based on environmental conditions. By monitoring temperature and irradiance, the system adjusts the number of PV modules connected in series to optimize the string voltage for current conditions, thereby improving energy harvesting efficiency while maintaining compliance with electrical code safety requirements.
2Productivity
If the PV string voltage is increased to improve energy harvesting efficiency, then the efficiency increases, but the voltage may exceed the maximum regulatory voltage specified by electrical codes
Solution Approach 1:
The patent implements a feedback control system that continuously monitors environmental conditions (temperature, irradiance) and system parameters (voltage, current). Based on this feedback, the controller dynamically adjusts the PV string configuration to maintain optimal efficiency while ensuring the voltage remains within the maximum regulatory limits specified by electrical codes. The system uses real-time data to prevent voltage excursions that would exceed code requirements.
Solution Approach 2:
The system performs self-adjustment by automatically monitoring its own operating conditions and reconfiguring the PV string as needed. The controller assesses current temperature and irradiance levels, calculates the optimal string voltage, and autonomously connects or disconnects PV modules to achieve the desired configuration, thereby maintaining both efficiency and compliance without external intervention.
3Loss of energy
If more PV modules are connected in series to increase voltage and reduce line losses, then transmission efficiency improves, but the infrastructure costs and complexity increase
Solution Approach 1:
The patent employs dynamic reconfiguration of the PV string by incorporating switchable connections between PV modules. The system can adjust the number of modules in series based on operational requirements, allowing optimization of voltage for reduced line losses while maintaining manageable system complexity through automated control. This dynamic approach eliminates the need for fixed high-voltage configurations.
Solution Approach 2:
The system optimizes the balance between voltage level and system complexity by dynamically changing operational parameters. Rather than permanently configuring for high voltage to reduce line losses, the system adjusts voltage levels based on real-time conditions, achieving energy efficiency improvements without the permanent infrastructure complexity and costs associated with fixed high-voltage designs.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach increases energy harvesting efficiency by up to 0.3% and reduces line losses during power transmission, while also reducing infrastructure costs and labor requirements by optimizing the number of PV modules and strings.
Implementation Method 1
Solar power systems harvest energy from photovoltaic (PV) panels or modules, which generate energy from photovoltaic cells
Data Source
AI summary
A plurality of photovoltaic (PV) modules are configured into a PV string to generate a PV string voltage in a solar power system. The number of PV modules per PV string is based on operating conditions at the solar power system site and cause the PV string voltage to exceed a maximum voltage specification when operating at the lowest expected ambient temperature at the site, but only exceeds the maximum voltage specification for a limited number of occurrences for which the operating conditions at the site cause the PV string voltage to exceed the maximum voltage specification. Under control of a string voltage control circuit, voltage bypass circuits selectively bypass the bypass photovoltaic module so as to eliminate the PV module from the PV string voltage when the operating conditions at the site cause the PV string voltage to exceed the maximum voltage specification.