Solar-Thermal

The Centre has done pioneering work on solar thermal technologies. Design of solar hot water systems, dryers, space heating / cooling system is performed by using state-of-art computer software.
Some of the contributions of the solar-thermal energy group are listed below.

* Methods and tools to facilitate design and detailed optical performance evaluation of a large variety of linear solar concentrators have been developed.
* An improved technique to compute heat loss in flat plate solar collectors, linear concentrators, solar stills (including output of solar stills) has been developed. The method provides results very close to numerical solutions and thus eliminates the need for numerical solutions. It replaces the internationally well established empirical equations. It provides proper interpretation of test results.
* Test methods for thermal performance evaluation of following solar thermal devices have been developed.
• Box Type Solar Cookers-
Proposed method led to the development of the Indian Standard on Box Type Solar Cookers in 1991 and later its revision in the year 2002.
• Paraboloid Concentrator Solar Cooker-
Draft procedure submitted to the Ministry of Non-Conventional Energy Sources.
• Flat Plate Solar Collectors-
Result of round robin testing exercise and other studies were used in revising the Indian Standard on Flat Plate Solar Collectors.


Solar-Photovoltaic


Photovoltaic (PV) energy conversion has emerged as one of the leading alternative sources of energy for direct conversion of solar energy into electricity using solar cells. Worldwide a total installation capacity in the range of GWs has been achieved and a growth rate of 25% and more has continued for almost a decade now. A large number of PV companies has achieved production capcity in the range of 100 MW/yr and above. In fact this led to a severe shortage of Si which in turn has many silicon manufacturers develop facilities for Solar grade silicon.
The same trend is visible in India also and many existing and new PV companies are aiming for 100s of MW production capacity. Ministry of New and Renewable Energy has also given a boost to the PV programme by announcing a scheme for MW PV generation to be built and operated by companies with feed in tariff in the range of Rs. 12 to be provided by the ministry. This can make a significant impact towards mitigating the power outages that are so frequent due to the mismatch between the electricity requirements and generation capacities. Clean development mechanism (CDM) can also help financially since the PV systems are almost carbon neutral.

Third generation photovoltaic material concepts like
(1) multiple electron-hole pair generation,
(2) multiple energy threshold process and
(3) photon down- and up-conversion are being proposed for improving the solar cell efficiency.
These novel concepts are based on, to exploit the polychromatic solar spectrum for improving the solar cell efficiency by overcoming,
(1) transparency losses from the sub-bandgap photons,
(2) thermalization losses due to the absorption of the high-energy photons and
(3) modified electron-hole recombination process itself.
These concepts are completely based on the 'optical process' in the 'novel' materials for improving the solar cell efficiency, compared to the existing technological challenges like, the recombination losses, junction losses, and metal contact losses.

The restricted motion of electrons at the billionth of meter size (nanometer) is leading to unusual structural, optical, mechanical and electrical properties of materials. These nano-materials are generating great hope as ‘clean energy sources’ for the future to protect the ‘environment’, apart from addressing some of scientific challenges in various fields. The incoming project will be based on some of the above third-generation solar cell concepts realized from our recent research work, with nanoscale metal and semi conducting materials. For example,
(1) many-fold enhancements of absorption in quantum dots,
(2) modified electron-hole recombination process in quantum dots, and
(3) accelerated nanoscale energy transportation between quantum dots for multiple-energy threshold process and
(4) photon up-conversion process from ions doped nanocrystals

Photovoltaics lab in CES has been engaged in R&D on Photovoltaic systems and devices.A 25 KWp generator is situated on the top of the Synergy building and was established under an MNES project. The PV system consists of storage batteries and PV inverter. The inverter has capability to operate in stand alone, grid interactive or hybrid mode. ASI of Australia has made it to the design provided and no further support from the company is available at the present. The PV system has been successfully used to demonstrate the capability of roof top generators. Typically up to 100 units of electricity can be generated per day depending on the solar insolation, temperature etc. In fact, PV electricity may be best suited for applications involving a dedicated load to evacuate most of the generated power.

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