Solar string inverters are becoming fundamental in photovoltaic (PV) systems, acting as the crucial gateway between the production of solar energy and its conversion into usable electric power. PV panels generate DC (direct current) power by converting sunlight through the photovoltaic effect; however, most residential and commercial electrical appliances and power grids operate on AC (alternating power) power. This is where string inverters come into play and convert the DC power generated by a series or 'string' of PV panels into grid-compatible AC power.
The transition from DC to AC is a complex process involving a blend of power electronics and digital signal processing technology. Furthermore, advancements in inverter technology, including but not limited to energy storage capabilities, predictive maintenance features, and smart grid integration, are constantly improving the efficiency and reliability of PV systems. Hence, the string inverter's role is instrumental in making solar energy a viable and sustainable power source.
What is Solar String Inverter?
As mentioned above, a solar string inverter is vital in a PV power system, primarily responsible for converting the DC output produced by solar panels into AC. The operation of a solar string inverter involves several technological aspects, such as Maximum Power Point Tracking (MPPT), voltage step-up/step-down transformations, DC-AC inversion, and synchronization with grid frequency and phase. In string inverter configurations, multiple solar panels are wired in series (forming a "string"), and the combined DC output of these strings is then fed into the inverter.
The working of a solar string inverter begins with the MPPT, an electronic DC-DC converter that optimizes the synchronization between the solar array (PV cells), which produces variable voltage and current due to changing light conditions, and the inverter. By altering the input impedance, MPPT ensures the array operates at its maximum power point and maximizes the power extracted.
Following this, the DC power is inverted to AC power, which happens in two stages: a high-frequency DC-AC inversion followed by a 50/60Hz AC-DC-AC inversion. The high-frequency inversion allows small, lightweight transformers to increase the voltage, while the second inversion generates the final output synchronized with the grid's phase and frequency. It ensures the power generated by the PV system can be effectively used or fed into the grid.
How to Choose a High-Performance Solar String Inverter?
The following are the factors in choosing a high-performance solar string inverter:
ü Efficiency: Solar string inverter efficiency, often above 95%[1], impacts the conversion of DC power from the panels to AC power for the grid. Higher efficiency values reduce power loss and contribute to higher energy output and return on investment (ROI).
ü High Protection: String inverters with a high IP (Ingress Protection) rating ensure robust protection against dust, water, and other environmental factors. In addition, features like surge protection and anti-islanding protect against electrical faults and grid failures.
ü Ease of Installation: Lightweight, compact design and integrated mounting hardware streamline installation, which assists with saving time and various types of costs. Pre-wired and plug-and-play systems additionally reduce the complexity of on-site assembly.
ü Smart Operation & Maintenance: Advanced inverters feature remote monitoring and diagnostics to minimize interruption and optimize performance. AI-driven predictive maintenance can detect potential failures, schedule repairs, and enhance system longevity.
ü Multi-MPPT Inputs: Multiple Maximum Power Point Tracking inputs allow for independent optimization of different solar panel strings, accommodating variations in shading and orientation. It enhances system efficiency/output under diverse conditions.
Sungrow String Inverter: SG25-50CX-P2
The Sungrow string inverter, SG25-50CX-P2, is a highly recommended solar string inverter for a 1000 Vdc system, providing an impressive yield, smart operation and maintenance, affordability, and reliable safety. It refers to a type of multi-MPPT inverter and is designed for high yield, which is compatible with over 500W+ PV modules while having a 15A DC input. Conspicuously, its dynamic shading optimization mode and built-in PID recovery function enhance efficiency.
For ease of operation, it offers key component diagnosis and protection, smart IV curve diagnosis, and a grid fault record function for seamless remote management. It's also an economical choice thanks to its 34% weight reduction and plug-and-play buckle design, which helps reduce installation costs. Last but not least, safety is assured with an IP66 protection rating, C5 Anti-corrosion, DC Type I+II SPD, AC Type II SPD, and support for AFCI 2.0 function.
Final Words
Connect with Sungrow today and experience exceptional support. Your needs are our priority, and our dedicated service team is always here regardless of your location.
Reference:
[1] https://www.energysavingtrust.org.uk/sites/default/files/reports/Solar%20inverters.pdf