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

Sandia and Stirling Set Solar-to-grid Conversion Efficiency Record

On a perfect New Mexico winter day -- with the sky almost 10 percent brighter than usual -- Sandia National Laboratories and Stirling Energy Systems (SES) set a new solar-to-grid system conversion efficiency record by achieving a 31.25 percent net efficiency rate. The old 1984 record of 29.4 percent was toppled Jan. 31 on SES's "Serial #3" solar dish Stirling system at Sandia's National Solar Thermal Test Facility.

The conversion efficiency is calculated by measuring the net energy delivered to the grid and dividing it by the solar energy hitting the dish mirrors. Auxiliary loads, such as water pumps, computers and tracking motors, are accounted for in the net power measurement.

"Gaining two whole points of conversion efficiency in this type of system is phenomenal," says Bruce Osborn, SES president and CEO. "This is a significant advancement that takes our dish engine systems well beyond the capacities of any other solar dish collectors and one step closer to commercializing an affordable system."

Serial #3 was erected in May 2005 as part of a prototype six-dish model power plant at the Sandia Solar Thermal Test Facility that produces up to 150 kilowatts (kW) of grid-ready electrical power during the day. Each dish unit consists of 82 mirrors formed in a dish shape to focus the light to an intense beam.

The solar dish generates electricity by focusing the sun's rays onto a receiver, which transmits the heat energy to a Stirling engine. The engine is a sealed system filled with hydrogen. As the gas heats and cools, its pressure rises and falls. The change in pressure drives the pistons inside the engine, producing mechanical power, which in turn drives a generator and makes electricity.

Lead Sandia project engineer Chuck Andraka says that several technical advancements to the systems made jointly by SES and Sandia led to the record-breaking solar-to-grid conversion efficiency. SES owns the dishes and all the hardware. Sandia, a National Nuclear Security Administration laboratory, provides technical and analytical support to SES in a relationship that dates back more than 10 years.

Andraka says the first and probably most important advancement was improved optics. The Stirling dishes are made with a low iron glass with a silver backing that make them highly reflective — focusing as much as 94 percent of the incident sunlight to the engine package, where prior efforts reflected about 91 percent. The mirror facets, patented by Sandia and Paneltec Corp. of Lafayette, CO, are highly accurate and have minimal imperfections in shape.

Both improvements allow for the loss-control aperture to be reduced to seven inches in diameter — meaning light is highly concentrated as it enters the receiver.

Other advancements to the solar dish-engine system that helped Sandia and SES beat the energy conversion record were a new, more effective radiator that also costs less to build and a new high-efficiency generator.

While all the enhancements led to a better system, one aspect made it happen on a beautiful New Mexico winter day — the weather.

"It was a ‘perfect storm' of sorts," Andraka says. "We set the record on Jan. 31, a very cold and extremely bright day, a day eight percent brighter than normal."

The temperature, which hovered around freezing, allowed the cold portion of the engine to operate at about 23°C, and the brightness means more energy was produced while most parasitic loads and losses are constant. The test ran for two and a half hours, and a 60-minute running average was used to evaluate the power and efficiency data, in order to eliminate transient effects. During the testing phase, the system produced 26.75 kW net electrical power.

Osborn says that SES is working to commercialize the record-performing system and has signed power purchase agreements with Southern California Edison (SCE) and San Diego Gas & Electric (SDG&E) for up to 1,750 megawatts (MW) of power, representing the world's two largest solar power contracts. Collectively, these contracts require up to 70,000 solar dish engine units.

"This exciting record shows that using these dishes will be a cost-effective and environmentally friendly way of producing power," Osborn says. "SES is actively engaged in the commercialization of the system, called the ‘SunCatcher,' including continuing to prepare it for mass production, completing project site development and preconstruction activities, and establishing partnerships with substantial manufacturing and industrial organizations to develop a cost-effective manufacturing process and supply chain. The demonstrated high efficiency means more energy is generated for the given investment, lowering the cost of the energy delivered."

Untitled Document

RELATED ARTICLES

Floridians Seek To Let the Sunshine In Via Solar Power PPAs

Mike Antheil Florida, the Sunshine State, is infamously unfriendly to the solar market. Despite the abundance of prime sunshine, which ranks the state third in the nation for solar potential, less that 1/10th of 1 percent of Florida’s e...

Welspun Commissions 52-MW Solar Power Plant in India

Vince Font Leading Indian solar developer Welspun Renewables has commissioned the construction of a massive solar plant in the state of Maharashtra. The planned 52-megawatt (MW) solar plant will be located in the city of Baramati. The...

Regional News from the July/August 2015 Digital Edition of Renewable Energy World

Renewable Energy World Editors EcoFasten Solar announced that it launched a new mounting "Rock-It System" that it would be displaying during Intersolar. Product compliance was determined through testing per UL Subject 2703, which reviews integr...

SkyPower Inks $2.2 Billion Deal for Massive Solar Power Plant in Kenya

Eric Ombok, Bloomberg Kenya’s Energy Ministry and SkyPower Global Ltd. will sign a $2.2 billion agreement on Sunday that paves the way for the Canadian company to develop a 1-gigawatt solar project in East Africa’s biggest economy. The solar pro...

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! @megcichon @jennrunyon

FEATURED PARTNERS



EVENTS

Presenting at Infocast's Utility Scale Solar Summit 2015

Oct. 21, 2015 4:30-5:15pm Albie Fong, National Director, Solar Frontier ...

StartUp Green

AREI, American Renewable Energy Institute, in partnership with ...

Utility Scale Solar Summit 2015

Oct. 21, 2015 4:30-5:15pm Albie Fong, National Director, Solar Frontier ...

COMPANY BLOGS

Compression: That’s What It's All About

With Intersolar already 2 weeks behind us (how did that happen...

Behind Every Good Decision

When something about your business isn’t working, you set out to c...

Clean Energy Patents Maintain High Levels in First Quarter, Solar L...

U.S. patents for Clean Energy technologies from the first quarter of 201...

NEWSLETTERS

Renewable Energy: Subscribe Now

Solar Energy: Subscribe Now

Wind Energy: Subscribe Now

Geothermal Energy: Subscribe Now

Bioenergy: Subscribe Now  

 

FEATURED PARTNERS