12 September 2015 12:54:12 IST

A tale of two solars

Awareness is key when it comes to popularising photovoltaic solar technology over the readily accepted solar heat

Here are two stories, one of success and the other quite the opposite.

What India has achieved in the solar photovoltaic space is something that every Indian should be proud of.

But this wasn’t the case five years ago. Back then, India had 12 MW of solar power plants that fed electricity into the grids. Today, with 4,102 MW, India is among the leaders in solar technology. To put it in perspective, India’s solar capacity is now 340 times that of what it was five years back.

This is but a mere milestone on a long, long path ahead.

This year (2015-16), at least 2,500 MW of solar capacity is assured to be built and the number could possibly be as high as 3,500 MW.

And, very soon, around 10-15,000 MW of capacity will be put out to bid, which means that by 2018, India’s capacity could well approaching 20,000 MW.

Back in the day

Five years back, people had a vague idea about solar power. Today, practically everybody is (literally and figuratively) enlightened.

Both versions of solar: PV – the large, ground-mounted, utility-scale, as well as the rooftops – is gaining traction.

There is practically nobody in the industry, big or small, who has not considered a solar rooftop plant. Educational institutions are contributing handsomely — hundreds of universities and colleges have solar plants (if your institution does not have one, it might be a good idea to request your management to consider one.)

For residential rooftop plants, the economics do not seem to work out favourably, but ‘solar’ will soon make an appearance here when prices of electricity go up. That is inevitable, as we have seen in several places. For example, in New York, electricity prices are very high, and solar rooftops are growing at insane speeds.

India is a test-bed of technologies. The country has all kinds of technologies in its installations — crystalline silicon (which is the most common) to thin films, from fixed tilt to trackers that, like sunflower, keep facing the sun all the time.

Globally, thin films — where the semi-conducting material that generate electricity are coated on a substrate — account for 10 per cent of installations, but in the Indian market thin films have a share of 35 per cent, as they are said to work well in hot climates.

Solar leader

Whether or not India will meet the government’s target of 100,000 MW of solar by 2022 (the answer is ‘probably not’) is moot, but there is little doubt that India will be a solar leader with respectable installed capacity.

Now, look at the ‘other’ solar – solar heat, the ‘other’ story that I was referring to in the starting of the story.

You could not have missed it, if you had ever been to Shirdi or Tirupati or the Akshardham temple in Delhi, or the Brahma Kumari World Spiritual University, Mount Abu, or the Golden Temple in Amritsar.

As you may imagine, thousands upon thousands pour into these places of spiritualism and, these pilgrims need, apart from food for the soul, some food for the stomach also.

A case for solar heat

In all these places, (and many, many other temples, gurdwaras, churches and mosques in India,) food is given free. At several of these spiritual hotspots, the sun cooks the food. Shirdi is a great example —73 shining parabolic dishes pick up sun’s heat and help cook never less than 20,000 meals a day.

Against such lofty examples, it is a bit of a let down that making use of sun power for heat, as opposed to making electricity, has not yet caught on in this country.

Solar cooking is one area where a social impact investor would get the biggest bang for his buck. Globally, some 3 billion people cook food under harmful conditions. About 4 million of them die due to ‘household air pollution’ every year — a number that has doubled since 2009!

In India, 65 per cent of the population uses fuels such as wood, charcoal and dung-cakes for cooking. A million people die of the smoke from these fuels wreaking havoc in their lungs. The Global Alliance of Clean Cook stoves estimates than an average Indian woman spends 374 hours each year collecting fuel for making food.

Yet solar cooking is not taking off. Reason: economics.

Solar cooking is at a stage where solar PV was some ten years back, before the advent of intense research and scale. Without getting into details, suffice to say that installing and maintaining huge parabolic dishes is a more expensive proposition than spending on fuel. It works for holy places (and educational institutions) where economics is not an issue — funding comes from donations, and scale supports the operations.

For solar cooking to spread calls for careful intervention. Today, solar cooking is almost invariably done out of CSR funds, but when you give away something free, it has no value. If a system fails, few bother to replace it — they’d rather go back to their old methods of cooking than labour over getting a repair or a replacement.

Cooking is but only one of the few applications of solar heat. Industries can trap the sun’s energy for various applications. Those who have installed ‘solar collectors’ have shown that it could be done. Good examples are Universal Medicap Ltd in Gujarat, where 16 parabolic dishes generate 200 degrees of heat. TI Cycles in Chennai use solar heat to dry paint. The Mahananda and Chitale dairies in Maharashtra and dairy in Salem, Tamil Nadu use solar energy to pasteurize milk.

But strangely, large-scale industrial application of solar heat is not happening on the scale it ought to.

Electricity or heat?

So, how would you like to use sun’s energy? Convert sunlight into electricity, or trap sun’s heat?

Heat is a far more efficient way of using sun’s energy. Efficiency – how much of sun’s energy is converted into the electricity or heat that we want – is of the order of 50-80 per cent for heat, compared with the best-case 19 per cent for electricity. Heat applications (other than cooking) are cheaper. Here is a data point for that: a 1 kW solar PV system costs Rs 1 lakh; a 1 kW system needed for a 100-litre solar water heater costs Rs 18,000.

Then why is it that while PV has zoomed, the other solar remains stuck?

No prizes for guessing: awareness.

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