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by Marc Berman January 18, 2026, 8:14 am
Photovoltaic (PV) modules are fundamentally nonlinear, environment-dependent energy sources. Their electrical behavior is not defined by a fixed voltage or current rating, but by a continuously evolving I–V characteristic shaped by irradiance, temperature, aging, mismatch, and system-level interactions.
For grid-connected inverters, DC/DC converters, and MPPT controllers, the PV source is not a passive supply—it is an active participant in the control loop. As a result, validating inverter performance using a static DC power source inevitably masks critical behaviors such as tracking stability, transient response, and protection coordination.
Programmable power supplies—when designed as photovoltaic simulators—address this gap by reconstructing the electrical behavior of PV modules in real time, enabling deterministic, repeatable, and controllable testing that closely reflects field conditions.

To replicate PV behavior dynamically, a programmable power supply must first model the underlying physics of a PV module. A PV module is typically represented by an equivalent circuit consisting of:
From this model emerges the characteristic nonlinear I–V curve, defined by key operating points:
Crucially, this I–V relationship is not static. Changes in irradiance primarily shift current, while temperature strongly influences voltage. Partial shading, mismatch, and dynamic load interaction further distort the curve in ways that directly affect inverter behavior.

Unlike real PV modules, programmable power supplies do not rely on semiconductor junction physics to produce energy. Instead, they use high-bandwidth power-electronic control loops to behave electrically like a PV source. At the core of this approach is closed-loop control, where the power supply continuously measures its output voltage and current, compares them to a reference PV model, and adjusts its output in real time to maintain the correct operating point.
This allows the supply to:
In effect, the inverter “sees” a PV module—not because the physics are identical, but because the electrical response is indistinguishable within the control bandwidth.
Modern programmable PV simulators generate I–V curves digitally, often using:
These curves are not precomputed and static. Instead, they are evaluated continuously in real time, allowing the power supply to adjust its current limit dynamically as voltage changes. When an inverter’s MPPT algorithm perturbs voltage:
This interaction is essential for validating MPPT convergence speed, stability, and susceptibility to oscillation.
To replicate real-world PV behavior, programmable power supplies must also emulate time-dependent environmental effects.
Irradiance changes—caused by cloud transients or shading—primarily affect the available current. A PV simulator reproduces this by dynamically scaling the current component of the I–V curve while preserving its shape.
Fast irradiance ramps test:
Temperature impacts semiconductor junction voltage, shifting the entire I–V curve along the voltage axis. Advanced simulators apply temperature coefficients in real time, enabling:
These effects are difficult—if not impossible—to reproduce consistently using real PV modules.
A defining feature of a PV module is its non-ideal source impedance, which varies across the operating range. Programmable power supplies replicate this behavior by modulating output impedance through control algorithms rather than passive components.
This is critical because inverter control loops assume a certain source stiffness:
High-performance PV simulators are designed so that their dynamic response exceeds that of the DUT, ensuring that observed behavior belongs to the inverter—not the simulator.
In real PV arrays, partial shading introduces multiple local maxima in the P–V curve. Advanced programmable power supplies can emulate this by superimposing multiple I–V segments into a composite curve.
This capability is essential for testing:
Without this feature, MPPT validation remains incomplete and overly optimistic.
In regenerative architectures, programmable power supplies can sink power as well as source it, returning absorbed energy to the grid or internal DC bus. This enables:
While real PV modules can only deliver power, regenerative simulators enable closed-loop system testing without the logistical constraints of large physical arrays.

Programmable power supplies replicate the dynamic behavior of photovoltaic modules not by mimicking their physical construction, but by reproducing their electrical response with high-bandwidth, model-based control. Through real-time I–V curve enforcement, dynamic irradiance and temperature modeling, controllable source impedance, and fast transient response, they provide a deterministic and scalable platform for inverter validation.
As PV systems continue to increase in power, voltage, and control complexity, the fidelity of PV source emulation becomes as critical as grid simulation itself. In this context, programmable power supplies are no longer generic DC sources—they are essential tools for ensuring that inverter behavior observed in the laboratory faithfully reflects performance in the field.
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