July 13, 2010
The new Solmetric PV Analyzer is a complete electrical test solution for verifying and troubleshooting photovoltaic array performance. For each string, the analyzer measures current and power as a function of voltage. Measured results of the I-V and P-V characteristics are compared to the performance predicted by advanced built-in models. When predicted results match modeled results, system performance is verified. Any differences can offer insights into potential performance issues such as excess series resistance, failing cells, or module mismatch. The PVA solution is ideal for system verification during installation and for troubleshooting performance problems.
Benefits of the PVA-600 include: increased confidence in system performance at startup, identification of problems with equipment and interconnects, maintenance and performance logs, and guidance during troubleshooting. “Solmetric’s mission is to provide tools with embedded expertise to help make solar installers more effective.” said Solmetric President Willard MacDonald. “The new PV Analyzer exemplifies this. It enables better installations and faster repairs by providing actual measurements where before there could only be guesses.”
Irradiance and Temperature Measurement Modes
For accurate predictions of I-V and P-V curves, irradiance and cell temperature must be known. The PVA-600 derives these values in several ways. With a novel “array-as-sensor” mode, the PVA extracts the irradiance and cell temperature mathematically from the measured I-V data. This technique effectively uses the array itself as the sensors, so external sensors are not required. This method allows detailed comparison of the shapes of measured and predicted I-V curves, even under conditions of changing irradiance and temperature. Irradiance and cell temperature can also be measured and entered into the PVA either manually or automatically with an optional wireless sensor accessory kit.
PV Model Choices
The Solmetric PVA compares measured and modeled array performance. Several models are available, including the advanced model from Sandia National Laboratories. To specify the system configuration, the user chooses the module and inverter type, the number of modules, and the array orientation. Strings up to 600V and 20A can be measured and compared to the model.
At a cost of $2,595, the PVA-600 brings full I-V curve tracing and unprecedented analysis capabilities within reach of any installer. The PVA-600 includes a Measurement Unit, a wireless USB interface, and PVA software for Windows™. A laptop or UMPC is required but not included. The wireless sensor kit is available as an option for $1,495. Currently the PV Analyzer is available for sale in North America, and international versions are planned later in 2010.
Background: Solmetric Corporation provides tools for solar installers, including the Solmetric SunEye for fast, professional solar site evaluation and the Solmetric PV Designer software for accurate simulations of PV systems. Since its introduction in 2006, the SunEye 110 has become the standard for solar site evaluation. Its integrated fish-eye lens and digital camera captures an image of the sky and horizon, and its on-board processor plots solar exposure at that location. Users can edit images, simulating the removal or addition of obstructions such as trees or structures. PV Designer takes the SunEye data to the next level by allowing the user to specify a roof plane, identify the location on the roof where SunEye readings were taken, drag-and-drop modules onto the roof, and simulate the energy output of the system. A sophisticated interpolation technique allows the software to predict the partial shading of individual modules anywhere on the roof.
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