Technologies

Offices, plants and installations

Concentrating Solar Power

PT1 Trough

The PT-1 parabolic trough collector system has a proven record of field operations. Abengoa Solar's longest-running PT-1 has been operating since 1990. The latest version of the PT-1 is the result of more than 20 years of continuous improvement aimed at increasing performance and durability while reducing costs and maintenance requirements. These breakthroughs have been made with financial support provided by the National Renewable Energy Laboratory, Sandia National Laboratories and the US Department of Energy.

The technical specifications of the PT-1 are:

Concentrator

The PT-1 concentrator is built according to a unique patented design that makes it very lightweight, yet exceedingly strong. The physical characteristics of the concentrator modules are:

Materials of Construction	Aluminum and steel
Reflective Surface	Silvered plastic film or reflective aluminum sheet
Dimensions Configuration (l x w)	20 ft x 7,5 ft (6,1 m x 2,3 m) one drive is two rows of up to 8 modules each

Receiver

The parabolic concentrator reflects solar energy onto the receiver at the parabola's focal point. The receiver is made of a steel absorber tube coated with a black chrome selective surface, and a surrounding envelope of Pyrex® glass to reduce heat loss. An anti-reflective coating on the glass increases light transmission. The receiver specifications are:

Absorber Material	Steel
Selective Surface	Black Chrome
Absorber Envelope Material	Borosilicate glass with antireflective coating
Maximum Operating Temperature	550° F (288° C)

Thermal Performance

Sandia National Laboratories independently measured the thermal performance of the PT-1 (Dudley, V. E. and Evans, L. R. Test Results: Industrial Solar Technology Parabolic Trough Solar Collector, SAND94-1117, Sandia National Laboratories, Nov. 1995). The efficiency based on the net aperture area for a silver reflector is plotted below.

Drive and Controls

The collectors track the sun automatically and continuously during the day. Local controllers regulate the collector tracking motors, while a single field controller monitors operation of the overall system. The control system incorporates safety devices that monitor sun, wind, system temperatures and pressures. Measured data and calculated values are stored at the controller and can be accessed locally or remotely using a modem or through the Internet. A unique multi-row configuration drives two rows of troughs in unison, reducing the number of moving parts and increasing reliability. Collector rows can be up to 8 modules (164 ft, 50 m) long. Typical row-to-row collector spacing is 18 – 20 ft (5.5 to 6.1 m).

Flexible Hoses

Fully insulated stainless steel hoses accommodate the motion of the receiver with respect to the fixed field piping. These hoses are designed for long life and require no maintenance.

Operation and Maintenance

PT-1 systems are fully automated and run unattended with minimal O&M requirements. Most problems can be detected through off-site monitoring. Periodic site inspections, every one or two weeks, are generally adequate to monitor system operations and to perform routine maintenance. Rain is very effective at washing the reflective surfaces to maintain performance. In drier climates, the collectors should be washed about every two months. Washing is accomplished by spraying the collectors with de-ionized water using a truck-mounted pressure washer and water tank.

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