Simulating Real Behaviors of Photovoltaic Energy Generation Systems for Validating Inverters
As photovoltaic (PV) systems scale from residential rooftops to utility-level power plants, the electrical behavior presented to grid-connected inverters has fundamentally changed. Modern PV inverters are no longer validated against a single static DC source, but against complex, time-varying electrical conditions shaped by irradiance fluctuation, temperature gradients, partial shading, string mismatch, DC-link dynamics, and grid-side interactions.
From a power testing perspective, PV simulation is not an end in itself—it is a means to validate the electrical, control, and protection behavior of downstream equipment, including string inverters, central inverters, DC/DC converters, energy management systems, and hybrid PV–storage architectures. Depending on the test objective, the Device Under Test (DUT) may range from a single MPPT channel to a multi-megawatt inverter system.
It is within this context that two terms are often used interchangeably—but should not be: Solar Panel Simulator and Solar Array Simulator. While both aim to emulate photovoltaic energy sources, they represent fundamentally different levels of system abstraction, test intent, and engineering complexity.
Solar Panel and Solar Array: Differences
A solar panel is a basic physical unit composed of photovoltaic cells connected in series and parallel to produce a limited voltage and current output. Electrically, it is characterized by a relatively low power rating (typically hundreds of watts), a single I–V curve, and localized environmental dependency. From a testing standpoint, a panel represents the minimum building block of a PV system.
A solar array, by contrast, is a system-level construct. It consists of multiple panels assembled into strings, multiple strings combined into arrays, and often multiple arrays feeding a single inverter or DC collection bus. The electrical behavior of a solar array is therefore shaped not only by individual panel characteristics, but by string configuration, mismatch effects, cable impedance, combiners, protection devices, and dynamic interactions between parallel paths.
Crucially, an inverter never “sees” a single panel in real operation—it interacts with the aggregate electrical behavior of an array. This includes high DC voltage levels (up to 1500 V), large current capability, distributed MPPT behavior, and transient phenomena during irradiance ramps or grid events. As a result, simulating a panel and simulating an array serve entirely different validation purposes.
Comparison of Solar Array Simulator and Solar Panel Simulator
From an engineering standpoint, the distinction between a Solar Panel Simulator and a Solar Array Simulator lies in power level, dynamic fidelity, scalability, and system relevance.
A Solar Panel Simulator is typically a low- to mid-power DC source designed to reproduce the I–V curve of a single panel or a small string. It is well suited for component-level development, MPPT algorithm verification, educational use, or early-stage inverter prototyping. These systems emphasize curve accuracy and ease of configuration, but generally operate at limited voltage and power levels.
A Solar Array Simulator, in contrast, is designed to represent the electrical behavior of real PV fields. It must support high DC voltage, high current, fast transient response, parallel operation, and long-duration stability. More importantly, it must remain electrically “stiff” under dynamic load interaction, ensuring that inverter behavior is evaluated against the source, not masked by simulator limitations.
To illustrate this difference, consider two typical market examples:
- A bench-top solar panel simulator (hundreds of watts to a few kilowatts) is commonly used to validate MPPT tracking logic under static or slowly changing irradiance profiles.
- A utility-scale platform such as the ActionPower ATE TITAN Solar Array Simulator is engineered to emulate large PV arrays supplying hundreds of kilowatts to megawatts, supporting fast voltage and current dynamics, parallel scalability, and direct coupling with grid simulators for full PV–inverter–grid interaction testing.
These two systems do not compete—they serve different layers of the same validation hierarchy.
Suggestions on What to Consider to Choose the Right One
When selecting between a Solar Panel Simulator and a Solar Array Simulator, the decision should follow a structured, application-driven evaluation process rather than nominal power rating alone.
Step 1: Define the DUT and test boundary
Is the DUT a single MPPT channel, a string inverter, or a central inverter connected to a DC collection system? If the DUT operates at system voltage and power, panel-level simulation is inherently insufficient.
Step 2: Identify operating voltage and current envelopes
Residential- or component-level testing may remain below 1000 V and a few kilowatts. Utility-scale inverters require simulators capable of sustained high-voltage, high-current operation without derating.
Step 3: Evaluate dynamic requirements
MPPT tracking, irradiance ramps, fault recovery, and DC-link interaction impose fast transient demands. The simulator must respond faster than the DUT control loops to avoid influencing test outcomes.
Step 4: Consider scalability and future expansion
R&D setups often evolve. Modular or parallel-capable solar array simulators allow expansion from prototype testing to pre-certification and system validation without changing the test philosophy.
Step 5: Assess integration with grid simulation
For grid-connected PV systems, DC-side simulation cannot be isolated from AC-side behavior. Solar array simulators that integrate seamlessly with regenerative grid simulators enable full-chain validation under realistic grid conditions.
Summary
The difference between a Solar Panel Simulator and a Solar Array Simulator is not semantic, it reflects two distinct levels of photovoltaic system abstraction. Solar Panel Simulators address component- and algorithm-level validation, while Solar Array Simulators are indispensable for system-level inverter testing under realistic electrical stress and operating dynamics.
As PV systems continue to scale in power, voltage, and grid interaction complexity, inverter validation increasingly demands array-level fidelity rather than panel-level approximation. Selecting the right simulation approach therefore requires aligning the simulator’s electrical behavior with the real operating environment of the DUT—ensuring that test results reflect inverter performance, not the limitations of the test source itself.
