|Why the Power Supply is Critical
for PV Simulations
Many solar inverters generate AC ripple on their DC input, which is connected to the photovoltaic array. For single phase inverters, the frequency of this ripple is twice the line frequency (120 Hz for US models). The simulator’s power supplies must not suppress this ripple as a function of their regulation loop.
An increasing number of inverters (and virtually all micro-inverters) accurately measure amplitude and phase of the ripple voltage and current to quickly track the Maximum Power Point (MPP) of the array. This approach allows tracking the MPP at a much higher speed when compared to conventional dithering techniques (also called perturbate-and-observe). Faster tracking of the MPP results in a much higher overall efficiency in cloudy conditions, where the irradiance is constantly changing.
It is likely that all solar inverters will use this approach in the near future, since end users are very sensitive to the overall efficiency of their solar energy installations.
Introducing the Elgar TerraSAS
The TerraSAS consists of programmable DC power supplies, a rack mounted controller, keyboard and LCD display with control software and GUI interface, output isolation and polarity reversing relays and a unique PV simulation engine that controls the power supply. This combination of hardware allows the TerraSAS to simulate most test protocols or combination of events that a solar installation will be subjected to. Power supplies are available in 1-15KW increments to simulate arrays up to 1MW.