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I have known Madhusudhan Rao (Madhu) for a while, from 1998 to be precise. He even “claims” that I was his first boss while we were both at Sify – though fortunately for him I was his boss exactly for a day, as I was fired over some trouble I had with the management the day after he joined my team.

After that rather short and eventful introduction, I met him almost a decade later. By then, both of us had graduated into cleantech. I had stuck to my consulting, research and marketing roles, but I saw that Madhu had gone back to his roots – being an engineer.

I was pleasantly surprised – and much impressed later – to find that he had done a good amount of engineering research on his own, collected patents and all, everything focused in the domain of sustainable heating and cooling.

Sustainable energy and cleantech sectors are gaining significant traction both in terms of the value they bring to the table in a world increasingly concerned about climate change. In addition, many investors I meet are keen on assisting innovative technologies that have a good likelihood of disruption.

I hence thought I will spend some time with Madhu and provide a profile of his company and efforts.

His company Oorja Energy, based out of Hyderabad, works in two main domains – One, SOLAR THERMAL solutions, and the other (non solar) SUSTAINABLE COOLING solutions.

Madhu with his machine

Madhu with his machine

I find many of his concepts quite indigenous and original, and thus these have a high likelihood of succeeding for India, where many times I find western cleantech concepts imported and force-fitted – doesn’t always work well.

I thought I’d provide an idea of what Ooraj Energy does in solar thermal, specifically medium and high temperature solar thermal heating, in this post. In another post, I will provide details on some interesting cooling solutions his company is working on.

Not Just Solar PV, Also Solar Thermal

With more awareness about Solar Photovoltaics for electricity generation, we are now seeing their adoption in greater numbers, aided by lower cost per unit. But electricity is only one form of energy consumed by us. A good chunk of the electricity or a primary fuel like coal, diesel, gas etc. is used for heating and cooling needs that cannot be addressed by Photovoltaics or at the very least, cannot be addressed by Photovoltaics in an efficient manner.

This is where solar thermal makes its entry.

Many every day products that we use require heat in their manufacturing or processing. The chocolate we eat requires heat in its process (cocoa roasting), so do the things we drink – milk (pasteurization), carbonated beverages, alcoholic beverages etc.

Even products like cars required heat for drying paint, electroplating of components. The moulds in which steel wheels of a locomotive are casted have to be pre-heated to 300 deg C, food produce (wheat, tomato, fish, cardamom etc.) needs to be dried before storage and tools at hospital need to be sterilized using steam before their reuse.

There are many such processes where burning of fossil fuels like diesel, gas, furnace oil or even coal. We cannot imagine an industrial process today that does not burn fossil fuel today in its manufacturing process – paper, rubber, metals, plastics, chemicals, pharmaceuticals, processed foods, cement…..the list is endless.

So, unless these industrial processes move from burning of fossil fuels to using renewable sources, we will see pollutants like Carbon dioxide, Carbon monoxide, Sulphur and Nitrogen Oxides, heavy metals like Mercury, Arsenic etc. and small particulate matter continued to be released into the atmosphere.

Efforts like Make in India need to be balanced with adapting, improvising and continuously innovating ways to reduce pollution that increased manufacturing is inevitably going to bring.

Solar Concentrators

A small group of early adopters have now started using Solar Concentrators to generate heat for different industrial processes. Solar Concentrators can provide heat or steam from 80-250 deg C that is typically required in most process industries. The common example of such concentrators that many might be aware of is the installation for large scale cooking at Tirupati or Shirdi.

Such solar thermal applications are poised to provide significant share of the total industrial heating requirement, as can be seen from the projection below:


(Source: International Energy Agency)

Oorja manufactures different types of solar concentrators required for different needs.

1. PTC 300: is for high temperature requirements upto 300 deg C. This parabolic trough uses a special evacuated tube receiver that can operate upto 400 deg C.


PTC 300

Technical Specifications of PTC 300:

Reflector Material
Solar-grade Anodized Aluminium Mirror Sheet
Absorber Tube
Evacuated Vacuum Tube
Steel Pipe Stainless Steel (SS316)
Length 2000 +/- 2mm
Outer Diameter 45 +/- 0.5mm
Glass Pipe Material – Borosilicate
Outer Diameter 84 +/- 2mm
Operational Parameters Thermal Loss – 250 W/m @400 deg C
Max. Operating Temperature – 400 deg C
Heat Transfer Medium
Water (or) Synthetic Oil (Auto Ignition Temperature 370 deg C)
~ 50% at 300 deg C

2. PTC 150: is suitable for lower temperature requirement up to 150 deg C. At peak, this trough can delivery upto 200 deg C.


PTC150 Installed at a Customer Site

Technical Specifications of PTC 150

Reflector Material
Solar-grade Anodized Aluminium Mirror Sheet
Absorber Tube
Evacuated Vacuum Tube
Absorber Pipe Tempered Copper
Length 1700  +/- 2mm
Outer Diameter 12 +/- 0.2 mm
Glass Pipe Material – Borosilicate
Outer Diameter 53+/- 0.5 mm
Operational Parameters Thermal Loss – 200 W/m @200 deg C
Max. Operating Temperature – 200 deg C
Heat Transfer Medium
Water (or) Synthetic Oil (Auto Ignition Temperature 370 deg C)
~ 50% at 150 deg C


3.SOL4: Oorja also manufactures a smaller solar concentrator suited for solar cooking for small communities like schools, hostels, ashrams etc.

These models are manufactured to spread the use of solar concentrators at grass roots level and are mostly purchased by NGOs at a reasonable cost.


Installation of SOL4 at a school in Jharkhand 



New improved version of SOL4

Technical specifications of SOL4:

Reflector Material
Solar-grade Anodized Aluminium Mirror Sheet / Glass Mirrors
Heat Transfer Medium
Direct Heat Transfer to the Vessel
~ 60% at 150 deg C

Solar-based Cooling Solutions from Oorja Energy

Today, most of the cooling is done using electricity that operates our air conditioners or large air conditioning plants.

With economic growth, one can expect a significant growth in the use of air conditioning in India.

Using air conditioners at home may be a personal choice for us, but for many industries and commercial buildings there is no choice. So, embracing cooling technologies that do not depend on electricity would seem like a smart choice for many industries and commercial buildings as the air conditioning penetration increases and demand for electricity increases exponentially. There is a solar solution for cooling. Just as electrical energy drives the compressor in the cooling system, solar heat can be used to drive adsorption chillers that can provide cooling. A 100 Tons electrical compressor typically uses 80-100 KW at its peak, but a 100 Tons adsorption chiller will use less than 4 KW electricity. Solar cooling involves generation of solar heat that drives an adsorption chiller to provide chilled water. Chilled water is then circulated to produce cold air using fan coil units (like in hotels) or air handling units (like in large centrally air conditioned offices or hospitals).

A typical solar cooling schematic is shown below:


Oorja manufactures Thermally Driven Chillers called Adsorption Chillers. Adsorption Chillers use Silica Gel and Water, with water acting as the refrigerant instead of environmentally harmful refrigerants like R22 or R410A that electro-mechanical chillers use. There are four models of Adsorption Chillers that are manufactured by Oorja:

Model No. Capacity
ADCM7-35 10 Tons
ADCM7-210 60 Tons
ADCM7-315 90 Tons
ADCM7-630 180 Tons



10 Tons Adsorption Chiller Developed by Oorja

Oorja Energy Engineering completely manufactures all their solar heating and cooling equipment in India. Over last six years, they have installed such solutions for many customers and are now gearing up to expand their operations to cater to significantly increased demand since early this year.

Madhu’s Perspectives on Solar Thermal Vs Solar PV

“We may be seeing rub off effect of the popularity of Solar Photovoltaics (on solar thermal)”, says Madhusudhan Rao.

He has one word of caution though. “Unless we continuously innovate to offer products and solutions to suit the customer needs and offer at the right price point, we may face the same scenario as in Solar Photovolatics or Solar Water heaters where imported components dominate the market. Continuous product development and creating our own intellectual property has been our mantra to be a leader in providing cleantech based heating & cooling solutions.”

I’d say to both industries and investors:

Keep an eye on solar thermal innovations and applications, such as Oorja Energy’s. Solar thermal does appear less scalable than solar PV, but that might be compensated for by the fact that solar thermal apps might actually solve more critical pain points for the industry and have much better pay back periods than solar PV.

Solar Heating for industrial processes and Solar Cooling are most viable in India due to various factors like high solar radiation, high electricity & fuel prices and high & increasing demand. With expected increase in manufacturing activity in India (refer to the image below), investments in Solar & Energy Efficient Heating & Cooling solutions by Indian manufacturers will help them have stable fuel input costs over long them to maintain competitive edge.

If there are investors or industries keen on talking to Madhu to explore working opportunities, you can connect with him at his web site, or drop in a note in the comments here, or send me a note at narsi [at] eai [dot] in and I will connect you folks. Or of course, at LinkedIn – Madhu is here at LinkedIn