Five concentrating technologies are in scope. Which one suits an enterprise depends on the temperature it needs, the roof or ground it has, and what it can maintain.
Solar photovoltaic panels make electricity. Concentrated Solar Thermal makes heat — and delivers it as hot water, thermic fluid or steam into an existing boiler or process line. For a factory whose energy bill is mostly fuel rather than electricity, these are entirely different propositions. Above roughly 120 °C, flat-plate solar collectors are no longer sufficient and a concentrating collector is required.
| Technology | Working temp. | Conc. ratio | Module area | Typical use in this project |
|---|---|---|---|---|
| Parabolic trough collector | 120–300 °C | 10–100 | 10–50 m² | Steam and thermic fluid for textile processing, chemicals, effluent treatment. Roof-mountable subject to structural load; needs a larger footprint. |
| Paraboloid dish (dual axis) | 120–400 °C | 50–2000 | 50–250 m² | Medium-temperature process heat. Used at Natural Capsules, Puducherry. |
| Linear Fresnel reflector | up to 400 °C | 10–100 | 20–50 m² | Higher-temperature steam where ground area is constrained. |
| Scheffler dish (fixed focus) | 90–200 °C | 20–100 | 5–20 m² | Cooking, drying and pasteurisation. The most widely installed CST type in India. |
| Non-imaging concentrator (xCPC) | up to 250 °C | 5–25 | 2–10 m² | Boiler feed-water pre-heating and hot water. Simple to operate; used at the Dehradun silk reeling unit. |
Heat transfer medium may be pressurised water, steam, thermic oil or molten salt depending on temperature and application.
Applications demonstrated or assessed under the project include food processing and cooking, textile dyeing and processing, dairy pasteurisation, laundries, component washing, chemical and pharmaceutical processing, tea withering and drying, rice parboiling, leather effluent treatment, vapour absorption cooling, and hospital sterilisation and laundry.
Temperature is the first filter, but not the only one. Available roof or ground area, structural load capacity, direct normal irradiance at the location, the fuel being displaced and its price, and the operating hours of the process all bear on which technology is appropriate — and on whether CST is appropriate at all. Every project supported here is preceded by an independent site assessment.