Utility Scale Solar Modeling

Convenient In-Application Utility Scale Solar Modeling Tools

In Product Update by info@pvcomplete.com

PVSketch Mega includes not just one, but two, convenient in-application energy modeling tools to calculate accurate utility-scale solar project production estimates during early stage projects.

Of course, PVSketch Mega includes NREL’s PVWatts, which most in the solar industry have used at one time or another for modeling. PVWatts computes a reasonable estimate of production values based on typical industry module and inverter averages, without requiring many specific project data points. It’s a great tool in the early stages of a project in which you need a “good enough” estimate before final equipment decisions have been made.

But the software also includes a second, far more sophisticated in-application energy modeling tool based on CASSYS. The CASSYS open source code was originally developed by Canadian Solar as an internal tool in response to the company’s frustration that there was no way to interact programmatically with PVSyst, requiring a separate manual data entry process for every project scenario. The Canadian Solar team set out to build an automated modeling tool that would produce results with less than 0.5% deviation from PVSyst, and invested a great deal of time and expertise in validating the software.

PVSketch Mega’s advanced production model serves as a precise hour-by-hour 8760 data modeling tool for use when a project has locked down actual module and inverter equipment, assumed soiling losses, transformer efficiency and other loss factors. As part of PVSketch Mega, it allows users to complete thousands of computations programmatically without having to manually type in all of the data points for each unique project scenario.

The advanced production model evaluates solar module performance using the “standard” or single diode model. It obtains STC condition parameters for the module from a .PAN file. It calculates module behavior for several non-standard operating conditions such as open circuit, fixed voltage and maximum point tracking. Values are then converted from module-level to array-level, and applies thermal, module, module mismatch, incidence angle modifier and wiring losses are in accordance with user input values.

The model also computes shading factors on the beam, diffuse and ground-reflected components of incident irradiance based on the sun position throughout the day. This near shading analysis is available for panels arranged in unlimited rows or fixed tilt configurations. If the unlimited row model is used, PVSketch Mega’s advanced production model considers the length of such rows to be large enough that any edge effects can be neglected in its shading model. This assumption reduces the calculation of the shading factor at different times of the day to a simple geometrical construct.

PVSketch Mega relies on a hierarchy of weather data sources to run its advanced energy model. First, the software seeks to download data from the National Solar Radiation Database (NSRDB). If NSRDB fails for a given location, PVSketch Mega then seeks to download data from the Photovoltaic Geographical Information System (PVGIS) database.

The widely used Hays and Perez models are also available in PVSketch Mega to calculate the plane of array irradiance.

With PVWatts for early stage design and PVSketch’s advanced energy model for more sophisticated PVSyst-caliber energy modeling, PVSketch Mega’s in-application tools empower the utility-scale project development process with more precise production estimates to better inform project decision making and enable superior project outcomes.