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Improving Solar Power Efficiency Through Level and Flow Control

Solar technologies use the sun’s energy to provide electricity, hot water, process heat and cooling. According to the U.S. Energy Information Administration, solar power presently provides less than 1% of U.S. energy needs, but this is expected to increase with the development of more efficient solar technologies. One way to enhance solar power efficiency is through the use of level and flow instrumentation to drive process improvement.

TYPES OF SOLAR COLLECTORS
Different solar collectors meet different energy needs. Passive solar designs capture the sun’s heat to provide space heating and light. Photovoltaic cells convert sunlight directly to electricity. Concentrating solar power systems focus sunlight with mirrors to create a high-intensity heat source, which then produces steam or mechanical power to run a generator that creates electricity. Flat-plate collectors absorb the sun’s heat directly into water or other fluids to provide hot water or space heating.
 
SOLAR LEVEL AND FLOW APPLICATIONS
Heat Transfer Fluid Storage: Large-scale solar collectors for electric power generation require a heat transfer fluid (water, thermal oils, or ionic liquids) to absorb the sun’s heat for generating steam. Arrays of mirrored panels convert the sun’s energy into +750° F (+399° C) thermal energy that’s hot enough to create steam for turbines. The mirrors focus sunlight onto pipes of heat transfer fluid that run along the mirror’s centerline. The fluid then boils water to produce steam. Thermal fluids also help provide hot water and heat. Thermal fluids are typically stored in pressurized tanks that require level monitoring.
Recommended Continuous Level Technologies: Displacer Controller, Guided Wave Radar
Recommended Point Level Technologies: External Cage Float

Hot Water Storage: High-temperature solar water heaters provide energy-efficient hot water and heat for large industrial facilities. Thermal storage in buffer tanks provides interfaces between collector subsystems and energy-using systems. The preferred solar storage vessel is a vertical cylindrical tank designed for the maximum pressure of the supply water source, which may be as high as 150 psi.
Recommended Continuous Level Technologies: Displacer Controller, Guided Wave Radar
Recommended Point Level Technologies: External Cage Float

Pump Protection: Flow switches protect pumps from damage due to leaks or if a valve is accidentally closed downstream. A flow switch will actuate an alarm and shut down the pump when flow drops below the minimum rate.
Flow Alarm: Thermal Dispersion Flow Switch for High/Low Alarm, or Flow Switch

LEVEL AND FLOW INSTRUMENTATION FOR SOLAR POWER EFFICIENCY