Ever since the Jawaharlal Nehru National Solar Mission (JNNSM) was launched in 2009, Solar PV has been the most talked about solar conversion technology in India, where as Solar Thermal usually gets relegated to the sidelines, or gets discussed as an after-thought. Considering the fact that India’s abundant solar energy resource is available equally for both Solar Photovoltaics and Solar Thermal, it is important that Solar Thermal’s potential is also highlighted appropriately.
Solar heat can be used broadly for two purposes – to generate electricity and to generate hot water which has many end applications. The latter can be divided into sub-categories based on the temperature to which the water is heated. The broad overview of the categories is as follows
- Concentrated Solar Power (CSP)In CSP, water is heated to 450 Deg C and the superheated steam is used to generate electricity. During the early part of the Phase 1 of the JNNSM, CSP technology was cheaper than Solar PV technologies, and the Ministry of New and Renewable Energy (MNRE) considered both the technologies at par, and divided the 1,000 MW allocation equally between PV and CSP. However, due to a variety of factors, a majority of the CSP projects that were allotted in 2010 are yet to be commissioned. There has been no further allocation of CSP projects since then. Since PV prices have also come down drastically relative to CSP, there are no takers for CSP projects currently.
- Solar Thermal (ST)The term Solar Thermal is the term used when solar energy is used to heat water to varying temperatures. The hot water finds use in domestic, commercial and industrial sectors. The 3 broad sub-categories under Solar Thermal are
- Concentrated Solar Thermal (CST) – Up to 250 Deg C (Medium temperature – Class 2)
- Enhanced Solar Water Heating System (E-SWHS) – 80-120 Deg C (Medium temperature – Class 1)
- Solar Water Heating System (SWHS) – 60-80 Deg C (Low Temperature)
According to MNRE, about 15 million tonnes of fuel oil is consumed industries (like textile, chemicals, plastics, etc.) for application temperatures below 250 Deg C, and about 35 million tonnes for temperatures above 250 Deg C. Deploying CSTs in these industries will lead to significant savings of fuel oil. The Phase 2 of the JNNSM targets installation of at least 400 systems, each with a solar collector area of approximately 250 square meters.
Enhanced SWHS is ideal for pre-treatment processes and heating processes in industries (eg. Automobile industry) that require temperatures up to 120 Deg C. At the lower end of the spectrum, there is the low temperature SHWS, which finds use in residential segment, especially as a replacement for electric geysers that are highly inefficient.
Apart from the above, Solar water cookers, steam generating systems, Air Conditioning and Refrigeration are applications for which Solar Thermal can be utilized.
Installation of solar collectors have seen remarkable growth since the launch of JNNSM, and the cumulative installations have tripled from about 3 million square meters in 2008-09 to about 9 million square meters at the end of the financial year 2014-15. The target is to achieve cumulative target of 15 million square meters by end of 2018-19.
According to a study conducted on behalf of International Energy Agency (IEA), the cumulative installed capacity of solar thermal collectors across the world stood at 270 GWth at the gend of 2012. Of this, two-thirds of the capacity (180 GWth) was in China and 16% (43 GWth) in Europe. India’s share stood at a meagre 1.7% (4.5 GWth). India, with its abundance of solar radiation, has the potential to increase its share enormously.
- Lack of awareness – The results of many surveys have highlighted this as one of the major challenges towards widespread adaption of Solar Water Heating Systems, especially in the residential sector. Lack of awareness includes both concept and technologies.
- Policy and regulatory framework – The growth of the sector between 2009 and 2014 was fuelled to a large extent by the subsidy offered under the JNNSM. The MNRE discontinued the subsidy scheme for Solar Water Heating Systems from 1st October 2014, and this discontinuation has been reported to have led to a drop in sales of the systems.
- Capital Cost – While the payback periods for Solar Water Heating Systems (SWHS) are very attractive, the initial cost is relatively high. The removal of the subsidy has made it dearer for the end users to buy SWHS.
- Quality – MNRE officials have acknowledged the fact that the quality of the systems available in India needs to improve if the sector can achieve its huge potential. Proper standards and monitoring mechanisms can address this problem.
- Maintenance – The lack of easily available trained SWHS technicians is another major issue that prevents many end users to switch over from electrical geysers to SWHS. Skills training will not only help in overcoming this challenge, but can also create huge employment opportunities.
Different forms of Solar Thermal conversion technologies can play a very vital role in reducing the reliance on fossil fuels and in the reduction of Green House Gas emissions. With its abundant solar resource, India has the potential to become a global leader in Solar Thermal, if the above mentioned challenges are addressed.
(This article originally appeared in Intersolar India portal)