The World's #1 Renewable Energy Network for News, Information, and Companies.
Untitled Document

Clearing Up Cloudy Understanding on Solar Power Plant Output

Sandia National Laboratories engineers have been studying the most effective ways to use solar photovoltaic (PV) arrays — a clean, affordable and renewable way to keep the power on. Systems are relatively easy to install and have relatively small maintenance costs. They begin working immediately and can run unassisted for decades.

Sandia National Laboratories researcher Matt Lave uses pyranometers like these to measure the amount of irradiance, or available sunlight. There are four round pyranometers, capped by small glass domes, on this device. The work shows that the variability of a point sensor is larger than the variability of a photovoltaic power plant. Credit: Dino Vournas

But clouds could dim industry growth: What happens when they cover part of a solar PV array and cause a dip in output, how big is the dip and how can a utility company compensate for it? Sandia researcher Matt Lave has been working to understand that drawback and determine just how much clouds can affect solar power plant output. Typically, sunlight is measured using a single irradiance point sensor, which correlates nicely to a single PV panel. But that doesn’t translate to a large PV power plant. “If a cloud passes over, it might cover one panel, but other panels aren’t affected,” Lave said. “So if you use the single point sensor to represent the variability of the whole power plant, you will significantly overestimate the variability.”

To get a more accurate picture of how clouds affect PV power plants, Lave partnered with Sandia engineer Josh Stein and University of California, San Diego professor of environmental engineering Jan Kleissl to develop a Wavelet Variability Model. The model uses data from a point sensor and scales it up to accurately represent the entire power plant. The model uses measurements from an irradiance point sensor, the power plant footprint — the arrangement and number of PV modules in the plant — and the daily local cloud speed to estimate the output of a power plant.

In many cases, output measurements from the power plant aren’t available, but point sensor data is, so the model is useful for estimating how much energy must be stored to make up for cloud-caused fluctuations.

The variability is a concern for grid operators as unanticipated changes in PV plant output can strain the electric grid. At short timescales, measured in seconds, sharp changes in power output from a PV power plant can cause local voltage to flicker. At longer timescales, measured in minutes, generating less PV power than expected produces balancing and frequency issues, where load can exceed generation. Backup systems such as battery storage to mitigate the variability can substantially add to the cost of a PV power plant.

Lave points to Puerto Rico, where changes in power output are required to be less than 10 percent per minute. “With this tool, you can estimate how often you’ll exceed that limit and determine how to mitigate those effects,” he said.

The team recently published a book chapter in Solar Energy Forecasting and Resource Assessment. Chapter 7, “Quantifying and Simulating Solar-Plant Variability using Irradiance Data,” offers metrics to characterize and simulate the variability of solar power plant output.

This work is supported by the Department of Energy’s SunShot Initiative, a national effort to make solar energy cost-competitive with traditional sources of energy by 2020 and greatly increase how much solar energy safely and cost-effectively goes to the electric grid. By helping grid operators solve variable short-term power generation problems, Lave said utilities will likely be more comfortable from a technical perspective with increases in the relative percentage of solar in their energy portfolios.

“It is important to accurately scale solar variability to ensure accurate grid integration studies and PV plant evaluations. Having a solid understanding of the effect of PV plant variability will encourage PV installations while helping to maintain a safe electric grid.” Lave said.

Untitled Document

RELATED ARTICLES

Stolen Solar Panels and Sabotage A Challenge for Powering India With Renewable Energy

Anindya Upadhyay, Bloomberg Disappointment spread across Tarun Singh’s face when he saw that parts of his solar power microgrid in eastern India’...

States Already Seek To Delay Clean Power Plan

Andrew Harris, Bloomberg Fifteen states led by coal-rich West Virginia asked a federal court to stall Obama administration rules intended to c...

Suntech Parent Company Buys Majority Share of US-based Suniva

Ehren Goossens Shunfeng International Clean Energy Ltd., the Hong Kong-based solar company controlled by billionaire Zheng Jianming,...

Sunrise in Pakistan as the Country Delves into Solar PV

Robert Harker Pakistan has joined the list of countries that are exploring solar power as a means to bridge critical energy generat...

PRESS RELEASES

Array Technologies’ DuraTrack HZ v3 Continues to (R)evolutionize at SPI

Array Technologies, Inc. (ATI) prepares to showcase its recently launched tracking syst...

Appalachian's Energy Center assists counties with landfill gas to energy projects

The Appalachian Energy Center at Appalachian State University recently completed a proj...

Early Bird Registration Deadline for GRC Annual Meeting is This Week

The deadline for early-bird rates for registration for the biggest annual geothermal ev...

Redesigned HydroWorld.com Video Gallery

Hydropower news and information, and interesting promotional announcements are now avai...

FEATURED BLOGS

Transitioning to Net-Zero Living

Judith and Jeffrey adore living in Belfast, Maine – a quaint harbor town of Belfast, Maine. They previously res...

The True Cost of Electric Vehicles in Australia

In order to avoid increased congestion, further greenhouse warming and lessen Australia’s reliance on imported ...

The Coming Multi-trillion Dollar Energy Investment Drive

In coming years, a multi-trillion dollar low-emission energy investment drive will get underway. Three catalysts wil...

The Perfect Elevator Pitch

The elevator pitch is a concise statement that grabs attention and communicates value, ideally leading to a next step...

FINANCIAL NEWS

Stephanie Hobby specializes in energy R&D and energy security and responds to general news media requests for information about Sandia National Labs.

CURRENT MAGAZINE ISSUE

Volume 18, Issue 4
1507REW_C11

STAY CONNECTED

To register for our free
e-Newsletters, subscribe today:

SOCIAL ACTIVITY

Tweet the Editors! @jennrunyon

FEATURED PARTNERS



EVENTS

Intersolar North America 2016

Exhibition: July 12 - 14, 2016; Conference: July 11 - 13, 2016 Intersola...

Intersolar South America 2015

Exhibition and Conference: September 1-3, 2015 Intersolar South America ...

Intersolar Europe 2016

Exhibition: June 22-24, 2016; Conference: June 21-22, 2016 Intersolar Eu...

COMPANY BLOGS

The Proof Is Not Always In The Pudding

One of the best ways to turn a skeptical prospect into a buyer is to giv...

Pushing Beyond The Cushion

Efficiency projects are all too often viewed as “optional” o...

Less Is More

When you’re giving a presentation, one of the easiest things to do...

NEWSLETTERS

Renewable Energy: Subscribe Now

Solar Energy: Subscribe Now

Wind Energy: Subscribe Now

Geothermal Energy: Subscribe Now

Bioenergy: Subscribe Now  

 

FEATURED PARTNERS