Sandia Solar Program News - Jan/Feb 2016

January/February 2016

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Latest Sandia Solar Programs News & Research


The Sandia Solar Programs e-newsletter features highlights, key activities, events, and publications. News is also available on Sandia’s Energy and Climate website. We welcome your feedback. Please e-mail comments and suggestions to We hope you enjoy this valuable resource!

Research Updates

Sandia’s Distributed Energy Lab Marks FY15 Accomplishments, Adds New Capabilities

Inverters at Sandia's Distributed Energy Technologies Laboratory

Sandia labs completed a number of enhancements to its Distributed Energy Technologies Laboratory (DETL) facility in 2015. Many of the updates extend cyber-security capabilities at DETL, such as Sandia’s ability to configure isolated networks for intrusion detection experiments. The communications-enabled control overlay allows for comprehensive evaluation of cyber vulnerabilities of distributed energy devices (DER) and controllers connected to the internet, fully leveraging Sandia's cybersecurity, controls, and high performance computing expertise. One application of this infrastructure is to demonstrate the effect of cyber attacks and communication delays on large interconnected power networks using a combination of hardware and simulation (hardware-in-the-loop) for both power and communications networks. The Emulytics[TM] platform (i.e., SCEPTRE, MiniMega, and Firewheel) enables high-fidelity emulation of communication networks of arbitrary size and complexity. This new platform extends cyber-security capabilities for Sandia by facilitating integration with physical DERs at DETL. POC: Jay Johnson

PV III-V cell

Sandia Labs conducts PV research as part of ARPA-e MOSAIC program

Massachusetts Institute of Technology and Sandia National Laboratories have initiated a collaboration on Wafer-Level Integrated Concentrating Photovoltaics that reduces the complexity of tracking needs. The team’s innovative approach uses wafer-level micro-concentrators to significantly enhance sunlight concentration onto high-performance III-V micro-PV cells (pictured). The concentrator is also a diffuse solar radiation collector, allowing the technology to operate in regions with high levels of diffuse sunlight. The team will use standard semiconductor processes to fabricate the system, ensuring high-precision, yet low-cost manufacturing. The Wafer-Level Integrated Concentrating Photovoltaics is one of 11 projects funded by ARPA-e under the Micro-scale Optimized Solar-cell Arrays with Integrated Concentration (MOSAIC) program. The project also builds upon Sandia’s prior work in the microsystems-enabled photovoltaics (MEPV) Grand Challenge.

The MOSAIC program focuses on the design of technologies and concepts for a new class of cost-effective, high-performance micro-scale concentrating PV (micro-CPV) technologies  integrated into “flat plate” solar panels to improve their efficiency and cost. This micro-CPV approach addresses the constraints of conventional CPV, which, while highly efficient, has not been widely adopted due to its high cost, large size, and expensive solar tracking systems. Project teams will address these limitations by developing innovative materials, micro-scale manufacturing techniques, panel architectures, and tracking schemes. The MOSAIC program also includes a Small Business Innovation Research (SBIR) award category. POC: Anna Tauke-Pedretti

Image above shows a PV II-V cell with 250 µm diameter optical aperture

The falling particle receiver at the top of Sandia's solar tower

Sandia’s Continuously Recirculating Falling-Particle Receiver Placed Atop of the Solar Tower

Sandia began first-of-its-kind testing using its continuously recirculating falling-particle receiver atop the National Solar Thermal Test Facility (NSTTF). The falling-particle receiver drops sand-like ceramic particles through NSTTF’s concentrated sunlight beam, capturing and storing the heated particles in an insulated tank. Compared to conventional molten-salt systems, the falling particle receiver creates more available energy and cheaper storage costs with less material needed for heat transfer.  Sandia’s goal is to develop a prototype, cost-competitive falling-particle receiver with the potential for thermal efficiency greater than 90% and particle temperatures of at least 700°C.  POC: Subhash L. Shinde 

Sample Grid PV plot

GridPV Toolbox Version 2 Now Available

The GridPV toolbox models and simulates the integration of the distributed, or local, power generation into the electric power system. Simulations with this tool can be used to evaluate the impact of solar energy on the distribution system.

GridPV Toolbox is a fully-documented set of Matlab functions that can be used to build distribution grid performance models using the open source distribution modeling tool OpenDSS. The GridPV functions are useful for interfacing OpenDSS and Matlab to perform sophisticated analyses and graphically representing information from simulations. A set of functions is also included for modeling PV plant output in the OpenDSS simulation. The toolbox contains functions for overlaying  distribution feeders on satellite images using GPS coordinates.

GridPV version 2 was recently upgraded to include the following new features:

  • Updated MATLAB help menus for GridPV and a new user manual, including 20 new pages of documentation
  • Updated to use new OpenDSS System object
  • Uses the newest Sandia Wavelet Variability Model (WVM) for PV modeling
  • 25 new plotting features and functions

The documentation and toolbox are available for public download. POC Robert Broderick (6112). Image above shows an example GridPV graphic of a feeder voltage profile by line segment.

Largest Reduction of Solar Energy in 24 Years Recorded at the PSEL Linked to El Niño

Since before 1990, Sandia’s Photovoltaic (PV) System Evaluation Lab (PSEL) has been comprehensively recording solar irradiance data to accompany its outdoor PV testing. The unusual dip in 2015 solar energy at the facility prompted us to notice that other historic dips in the sun’s insolation, or the amount of sunlight shining on the earth, have coincided with the larger El Niño years. Prior to 2015-16, intense El  Niño  conditions occurred in 1991-92, 1997-98, 2004-05, 2009-10. Many smaller events are harder to detect and, to be fair, climatic changes in 1992 were mainly attributed to the eruption of Mt. Pinatubo. The current weather data at the PSEL along with a link to a summary of the historic data can be found on Sandia Labs' PV website. POC: William Boyson

El Nino Solar DETL
Annual average daily energy at Sandia Labs' PSEL

Sandia Labs Releases New Version of PVLib Toolbox

Sandia has released version 1.3 of PVLib, its widely used Matlab toolbox for modeling photovoltaic power systems.  The version 1.3 release includes the following added functions: 

  • functions to estimate parameters for popular PV module models, including PVsyst and the CEC ‘5 parameter’ model
  • a new model of the effects of solar spectrum on PV module current
  • code to access weather data from NOAA’s Integrated Surface Data network

PVLib version 1.3 can be downloaded for free at and is released under an open source software license. POC: Josh Stein.

Sandia Labs Releases Wavelet Variability Model (WVM)


When a single solar photovoltaic (PV) module is in full sunlight, then is shaded by a cloud, and is back in full sunlight in a matter of seconds, a sharp dip then increase in power output will result. However, over an entire PV plant, clouds will often uncover some modules even as they cover others, resulting in only small changes in plant power output. Thus, the power output of a PV plant is smoother than the power output of a single module. Sandia has published the Wavelet Variability Model (WVM), implemented in Matlab, to model the spatial smoothing of irradiance over a PV plant or neighborhood with distributed PV. The WVM release includes a readme file with details on use of the WVM function and examples showing the WVM function applied to simulate both central and distributed PV. POC: Matt Lave


Sandia Defines Solar Variability Zones

Sandia has defined solar variability zones by modeling solar variability across the country using a combination of ground measured and satellite derived solar irradiance measurements. The zones represent the magnitude of high-frequency (sub-minute) solar variability—changes in available sunlight—at each location. PV installations in locations with higher solar variability can, all else being equal, lead to larger voltage fluctuations on electric distribution grids than PV installations in areas of low solar variability. Thus, to understand and study the impact of PV installations in a specific location to distribution grid operations, it is important to know the solar variability at that location. To facilitate such studies, solar variability samples from each zone are available. POC: Matt Lave

Upcoming Events

Solar photovoltaic panels

NREL and Sandia host PV Module Reliability Workshop, Feb. 23-25, 2016

The National Renewable Energy Laboratory (NREL) and Sandia National Laboratories are jointly organizing the annual PV Module Reliability Workshop. This year’s event, to be held February 23-25, 2016, in Lakewood, CO, will bring together photovoltaics (PV) experts from  national laboratories, industry, and academia to discuss the most recent updates in photovoltaic system reliability and lifetime. Dr. Olga Lavrova will be chairing the PV systems and inverter reliability session. Advanced sign-up for the workshop is highly encouraged as we typically reach capacity and walk-in registrations will not be accepted. POC: Olga Lavrova

Sandia and EPRI to Host PV Symposium in May 2016

Sandia National Laboratories and the Electric Power Research Institute (EPRI) are pleased to host the third PV Systems Symposium, May 9-12, 2016, at the Biltmore Hotel in Santa Clara, CA, on technical issues related to PV systems and technologies. Core areas of focus will include PV performance modeling, distribution hosting capacity and screening methods, component reliability, as well as data-driven strategies for performing economically efficient system upkeep. POC: Josh Stein

Recent Publications

External Link Disclaimer: The appearance of hyperlinks does not constitute endorsement of the external Web site, the information, products or services contained therein.


In this issue



Solar Power PV Conference & Expo (formerly PV America), Boston, MA, Feb. 24-25, 2016

PV Module Reliability Workshop, Lakewood, CO, Feb. 23-25, 2016. Additional information under Upcoming Events, below.

PV Systems Symposium, May 9-12, 2016, at the Biltmore Hotel in Santa Clara, CA. Additional information under Upcoming Events, below.

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