Publications

PV array simulator development and validation

Gonzalez, Sigifredo G.; Kuszmaul, Scott S.

The ability to harvest all available energy from a photovoltaic (PV) array is essential if new system developments are to meet levelized cost of energy targets and achieve grid parity with conventional centralized utility power. Therefore, exercising maximum power point tracking (MPPT) algorithms, dynamic irradiance condition operation and startup and shutdown routines and evaluating inverter performance with various PV module fill-factor characteristics must be performed with a repeatable, reliable PV source. Sandia National Laboratories is collaborating with Ametek Programmable Power to develop and demonstrate a multi-port TerraSAS PV array simulator. The simulator will replicate challenging PV module profiles, enabling the evaluation of inverter performance through analyses of the parameters listed above. Energy harvest algorithms have traditionally implemented methods that successfully utilize available energy. However, the quantification of energy capture has always been difficult to conduct, specifically when characterizing the inverter performance under non-reproducible dynamic irradiance conditions. Theoretical models of the MPPT algorithms can simulate capture effectiveness, but full validation requires a DC source with representative field effects. The DC source being developed by Ametek and validated by Sandia is a fully integrated system that can simulate an IV curve from the Solar Advisor Model (SAM) module data base. The PV simulator allows the user to change the fill factor by programming the maximum power point voltage and current parameters and the open circuit voltage and short circuit current. The integrated PV simulator can incorporate captured irradiance and module temperature data files for playback, and scripted profiles can be generated to validate new emerging hardware embedded with existing and evolving MPPT algorithms. Since the simulator has multiple independent outputs, it also has the flexibility to evaluate an inverter with multiple MPPT DC inputs. The flexibility of the PV simulator enables the validation of the inverter's capability to handle vastly different array configurations.