Solar Thermal System
Solar thermal energy (STE) is a form of energy and a technology for harnessing solar energy to generate thermal energy or electrical energy for use in industry, and in the residential and commercial sectors. The first installation of solar thermal energy equipment occurred in the Sahara Desert approximately in 1910 when a steam engine was run on steam produced by sunlight. Because liquid fuel engines were developed and found more convenient, the Sahara project was abandoned, only to be revisited several decades later.
Solar thermal collectors are classified by the United States Energy Information Administration as low-, medium-, or high-temperature collectors. Low-temperature collectors are flat plates generally used to heat swimming pools. Medium-temperature collectors are also usually flat plates but are used for heating water or air for residential and commercial use. High-temperature collectors concentrate sunlight using mirrors or lenses and are generally used for fulfilling heat requirements up to 300 deg C / 20 bar pressure in industries, and for electric power production. However, there is a term that used for both the applications. Concentrated Solar Thermal (CST) for fulfilling heat requirements in industries and Concentrated Solar Power (CSP) when the heat collected is used for power generation. CST and CSP are not replaceable in terms of application. The 377 MW Ivanpah Solar Power Facility is the largest solar power plant in the world, located in the Mojave Desert of California. Other large solar thermal plants include the SEGS installation (354 MW), also in the Mojave, as well as the Solnova Solar Power Station (150 MW), the Andasol solar power station (150 MW), and Extresol Solar Power Station (100 MW), all in Spain
Performance of Solar Thermal Syaytem
Uncertainties in revenue over time relate mostly to the evaluation of the solar resource and to the performance of the system itself. In the best of cases, uncertainties are typically 4% for year-to-year climate variability, 5% for solar resource estimation (in a horizontal plane), 3% for estimation of irradiation in the plane of the array, 2% for losses due to dirt and soiling, 1.5% for losses due to snow, and 15% for other sources of error. Identifying and reacting to manageable losses is critical for revenue and O&M efficiency. Recently, a method to create “synthetic days” using readily available weather data and verification using the Open Solar Outdoors Test Field make it possible to predict Solar Thermal systems performance with high degrees of accuracy. This method can be used to then determine loss mechanisms on a local scale – such as those from snow or the effects of surface coatings on soiling or snow losses. Access to the Internet has allowed a further improvement in energy monitoring and communication. Dedicated systems are available from a number of vendors. Some systems allow setting performance alerts that trigger phone/email/text warnings when limits are reached. These solutions provide data for the system owner and the installer. Installers are able to remotely monitor multiple installations, and see at-a-glance the status of their entire installed base.
Components of Solar Thermal System
A solar thermal system for residential, commercial, or industrial energy supply consists of the solar array and a number of components often summarized as the balance of system (BOS). The term originates from the fact that some BOS-components are balancing the power-generating or energy-generating subsystem of the solar collector array with the energy-using side, the load. BOS-components include thermal energy-conditioning equipment and structures for mounting, typically one or more turbines for generating electric power, an energy storage device, a racking system that supports the solar array, evacuated pipes, heating solar chemical which convey heat as energy to turbine water and mounting components.
Efficiency of Solar Thermal System
Solar Thermal System efficiency is depends on efficiencies of various equipments used in process and it also depended by which technique we convert solar thermal energy into useable form of energy like electrical or mechanical. In solar thermal efficiency calculation, efficiency depends on how munch energy falls on panel , how munch percentage panel convert energy direct from sun irradiation , form changing efficiency and efficiencies of other equipments which involved into convergence process. solar thermal efficiency of any solar systems depends upon collector which we are using like for flat plate, evacuated tube type collector ranging from 1 to 5 %, and for cylindrical trough ,parabolic trough and fresnel flat collector it ranging from 5-10% and it ranges from 10-15% for helical state and paraboloid dish collector. Efficiency of solar thermal system is also largely affected by temperature difference of panel and ambient temperature. As temperature difference increases the convergence efficiency of solar panel decreases. Other natural parameters like geographical area of operation and weather condition of operation also affect the efficiency.