SOLAR TIPS

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11.SOLAR TECHNOLOGIES
11.1Solar Photovoltaic
Solar photovoltaic (SPV) cells convert solar radiation (sunlight) into
electricity. A solar cell is a semi-conducting device made of Silicon materials,
which, when exposed to sunlight, generates electricity. Solar cells are
connected in series and parallel combinations to form modules that provide
the required power. PV modules are manufactured by assembling the solar
cells after stringing, tabbing and providing other interconnections.
11.2 Concentrated Solar Power (CSP)
Solar Thermal Power Plant
Solar Thermal Power systems, also known as Concentrating Solar Power
systems, use concentrated solar radiation as a high temperature energy
source to produce electricity using the thermal route.
CSP requires 7.5 acres to 10 acres / MW.
High temperature solar energy collectors are basically of
11.2.1 Parabolic Trough Systems
Trough solar systems use parabolic curved/ trough shaped reflectors that
focus the sun's energy onto a receiver pipe running at the focus of the
reflector. The concentrated energy heats a heat transfer fluid (HTF), usually
oil, flowing through the pipe. This fluid is then used to generate steam which
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powers a turbine. In a parabolic trough system, the receiver can reach 400°
C and produce steam for generating electricity.
11.2.2 PowerTower Systems
The solar power tower plant comprises an array of heliostats (mirrors) which
concentrates the sun's rays on the top of the high tower where the solar
receiver is located. The receiver collects the concentrated sun radiation and
transfers the energy to generate steam. (The reflected rays of the sun are
always aimed at the receiver, where temperatures well above 1000° C can be
reached.) The steam drives the turbo generator thereby producing electricity.
11.2.3 Parabolic Dish Systems
The solar dish generates electricity by focusing the sun’s
rays onto a receiver, which transmits the heat energy to
an engine. The engine is a sealed system filled with
hydrogen, and as the gas heats and cools, its pressure
rises and falls. The change in pressure drives the pistons
inside the engine, producing mechanical power. The mechanical power in turn
drives a generator and produces electricity. The solar dish sterling system
could be well deployed for decentralised power generation. Parabolic dish
systems can reach 1000° C at the receiver, and achieve the highest
efficiencies for converting solar energy to electricity.
11.2.4 Thermal Storage Systems
A major advantage in a Solar Thermal Plant compared to SPV/other
renewable energy is the thermal storage system, i.e., before using the heat
to generate steam, a part of the heat can be stored for later use/ during peak
hours. Solar thermal energy can be stored at high temperatures using molten
salts/other materials. A part of the heat energy is stored as heat and the rest
is used for generating steam to run the steam turbine. The stored heat can
be used later to generate power. The collector field can be sized according to
the need. Thus, thermal Energy storage systems can extend the operational
time of Solar Thermal Power plants by 6-12 hours.
Storing heat energy is cheaper than storing energy in any other form. By
building a sufficiently large heat storage system, it is possible to generate
power even when the sun is not shining.