Tag Archives: Sunlight

Challenges of roof-top Solar: Can we have make them more non-reflective ?

Every new idea faces some challenges. Those which can rise up to them quickly and even before they become problems are the ones which have a future. Many articles speak of some opposition to Solar Power plants. Some don’t want it to cover large expanse of land, while others find that it changes the scenery around their habitat, thus an eye-sore. Wind power too has faced similar problems.

India  has through its National Action Plan for Climate Change, brought about 8 missions of which 3  look at the direction of energy efficiency with scope for renewable. As the power plant through Solar, which is comparatively new in implementation, in India matures, so would the problems. And the problems it would face would be unique to it.

English: Solar One power plant in Mojave Deser...

Large solar-plant in India, would not face much problems as long  as they are  installed in low density, arid to semi arid regions, for now. Although it would be better for the investors to do the Environmental Impact Assessment and have back up plans for adaptation. And those  close to rural habitation, must also think of innovation in case pressure in land due to population density increase. Which is a definite possibility in India.

However, Roof-top solar; which in my opinion is the real game changer in the immediate future; would be facing issues which the Indian Solar industry has not yet perhaps anticipated . The problem would be from the potential hazard of glint & glare of reflected sunlight, especially in high-density Urban settings. ( even the large rural SPV plants would have the problem if directly under flight path of the air-force / aviation industry )  The sooner the manufacturers and all related stake-holders wise up to it the better it would be for all.

In my earlier article on OPEX Solar I have already started receiving tremendous response. Therefore, I am able to anticipate the issues which could come up first hand. Buildings in any city are of varying hight. Tall buildings overlooking clusters of row-houses or commercial centre like malls, cinema halls and even hospitals and schools. Typical settings where one can seek business in roof -top solar. More often than not, these roof installation would be of a fixed type south-facing system angled in accordance to the latitude of the city. The reason to make them face south is for receiving the maximum  sunlight as the sun traverses the sky from dawn to dusk. While this would ensure maximum power-generation, it would also generate maximum ire from the poor souls who would be occupying the buildings which would be bouncing the reflected sunlight. And the Indian summer, well to put it mildly is very bright indeed. Not only would it add to the glare, in-fact the reflected heat if intense could also damage PVC pipes and other materials, if preventive steps are not taken before hand.

So what are the precautions one must take to avoid this situation ? Some article have already covered this issue. However I am for the solution and not flagging the problem and leaving it there.  While solar panels are designed to absorb sunlight to convert it into electricity, most commercially available PV panels today lose about 4 percent of their potential power output due to light reflection from the front surface of the cover glass. Solutions are already on the way, with Honeywell launching the SOLARC anti-reflective coating in February 2011. SOLARC materials are based on advanced materials used in semiconductor manufacturing. They are transparent coatings that improve the light transmittance through the glass that covers photovoltaic, or PV, panels, thus increasing the PV module efficiency and power output. These coatings also significantly reduce glare from the glass, allowing the PV panel to better blend with its surroundings.

Here one needs, especially in India to educate the potential investor to be ready to invest a little more on the prevention and precautions with respect to glint & glare. Especially to avoid the opposition, the type I have posted as links through out this article. India, needs the power through SPV. It is the only way to reduce the carbon emission, which is sure to increase as the Country grows. And as all know, carbon emission is a politically loaded subjected. It can bring intense pain or relief in terms of international relations in the years to come.

Should we lose out on the potential of the Sun, which India has in abundance due to wrong application, it would be a tragedy for the Nation.


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Green Business Ideas – Using Solar Panels as Glass Facade can reduce Heat Island Effect in Cities and earn LEED credits

glass facade

In the past week I was interviewed by two News media both electronic & print which were very excited about a report by scientists from the National Environmental Engineering Research Institute (NEERI) India,  on Glass Façade Buildings in the City of Mumbai, India  and how it is raising the overall temperature by more than 17° C in the surrounding area of the building. Although it could be true, one must explore about how this problem be addressed without making ‘glass’ a bad building material. Things are not always black or white, therefore I would use this as an opportunity to once more showcase how Sustainable Cities  could be planned.

Glass has been a tradition building material for eons now. Colored glass was found from the Babylonian era and some of the most beautiful Churches and Cathedrals draw their prime beauty from the Stained Glass murals. Glass is the only single medium which allows the external environment into the room in a controlled fashion. Which means one can enjoy rain, snow or bellowing wind swaying the tree tops without getting wet or cold and having that curly lock of hair firmly in place.

Yet uncontrolled use of glass can create problems, such as raising the ambient temperature of the city/town and making it warmer. While extensive use of glass in building façade may be considered a good thing to counter the harsh winter experienced in the temperate regions of the World, it is foolish in Hot climes.

The reasons are simple. The word ‘Green House‘ originally meant ( before Global warming became popular) a glass house which kept the temperature warmer than the freezing  European cold and let some plants & vegetables grow. This happens because the heat from the Sunlight gets trapped within the space by the default property of glass.

While this is good for designing a building in say Norway or Alaska, where every drop of Sunlight would bring in the warmth and perhaps help save in reduction of energy consumption required for district heating, the same principle would require enormous amount of  district cooling which otherwise would have been normal in case of a hot and humid city like Mumbai or any other city with similar climatic conditions. And those large  water-cooled Air-conditioning plants placed on the roof tops to cool the buildings do so by pumping cool air inside the buildings while sucking the hot air away and out into the surrounding atmosphere. So a total glass building would not only throw more hot air out into the cityscape it would also use more water to cool itself. Yes, there is air cooled A/c plants too and high-efficiency COP’s have the ‘Green’ label attached but it too consumes energy and heats the sorrounding it however saves on water. Only the most well designed and high-end commercial glass façade buildings conform to all Sustainability criteria. But it does not hold true for all.

Therefore while the building may look swanky and very western, I would caution the tenant in buying space there as their energy bills could shoot up. Moreover by default of design constrains, its cheaper to make the Glass Facade buildings near hermetically sealed. Further no one would want the Air conditioned space to get warm because of a leak in the window casing.

Now the above observations lead to some unique problems for India or for any Emerging Economy in the Third World with similar climatic conditions.

First is the heat & dust. Not only does glass buildings get warmer inside it turns ugly on the outside too because of the perpetual dust. And once the commercial buildings are sold it becomes the building owner association responsibility to take care of maintenance. Maintaining tall glass façade building does not come cheap. It requires a whole new engineering solution, such as façade cleaning lifts and trained people to do it.

Second, we are a ’emerging economy’. Which means only a few rich & super rich have the luxury of having uninterrupted power. Rest are routinely treated with planned load shedding / power cuts and have to generate their own power through fossil fuel smoke belching  Diesel generators. In case of longer duration of power failure, rationing is done to cut cost and even the generators are shut down. And in this case one has no choice but to sit in airless rooms breathing Carbon –Di– Oxide exhaled by the neighboring colleague and hoping to survive the day.

Third, in smaller Tier -II & III towns and even the cheaper business districts within the megalopolis  the buildings only ape the Glass Facade exterior with no  Fire Safety Norms as a priority, and are built by unscrupulous Builder developers who themselves are an ignorant lot along with little or no understanding of EHS ( Environment – Health – Safety ) nor it is understood by the general public. ( the whole of India has only 2-3 dedicated burns center, one in Mumbai. New Delhi has none. However thousands die each year through burn related accidents) . So Glass buildings which are not designed well may lead to catastrophe in case of fire. Further as some are built right upon the road-side in high density areas, during Earthquake or other calamities, it may only compound the problems further with razor-sharp glass falling all over. True the glass have built-in safety feature to shatter into small bits but bad fixing and poor quality glass do not perform as intended.

Business and Scientific report do not go hand in hand. But  Science must be heeded if Business is to thrive. Global warming and its associated risks are too well documented to be ignored.  ( read my article for details:  Climate change – the most significant emerging risks facing the world today ) If the City of Mumbai or any city with similar climatic conditions continues to grow in this fashion and Glass façade buildings become norm and not exception, we are looking at a serious problem.

So we come to the question of what would the Developers and the Public do post reading the NEERI report ? Will tall glass façade building vanish from the cityscape? No chance.

But saving Mumbai ( and other cities ) is a must. Therefore here I will present an alternate thought which the Glass manufactures like ASAI, MODI etc along with the Solar PV manufacturers would I hope discuss over cocktail & dinner and come back with great Eco Ideas which would at least help reduce the problem of Heat Island Effect. And for this we must look at BIPV.

CIS Tower, Manchester

Image via Wikipedia

Building Integrated Photo voltaic (BIPV) has been around for sometime. It produces electricity and can also act as a Glass Facade. (As the image to the right shows, the dark blue glazing with a logo on top )  Now this is an option which has not been explored to its full potential in India and the rest of the World because of the cost verses production of electricity. It is generally understood that BIPV which is still in its nascent stage needs to develop further to truly become the choice for Architects and Builders to consider using it as an alternative to Glazed Building. This can happen only when the cost of the product becomes near equal to that of conventional Double Glazing Unit ( DGU ) which we see all around the city of Mumbai. However we can speed up this process by simply bringing in the economy of scale.

So how does one bring about this economy of scale? Simple, by introducing the Green building concepts which require the use of Solar Power or Green Energy. Both in the TERI – GRIHA  and IGBC -LEED certification process require  to bring energy efficiency of about 14% to the Building Envelope ( skin of the building; the outermost wall /glass surface ) which  at times design constrain and economic factors make  very difficult to deliver. Further Green Building Norms also ask for 10% of the total building energy be drawn from Solar Power. This too, is difficult due to unavailability of required roof-top space in certain cases.


Now BIPV  are SPV  (solar photo voltaic) patches of  modules which is sandwiched  between glass.  It not only produces electricity but also reduces the amount of Sunlight from entering the building which is known as the SHG factor for glass ( Solar Heat Gain). So this can act like ceramic frit-glass, which too is an architectural favorite as it has lower SHG factor  and yet have dual function. Further in the Green Building rating system one looks for high SRI  (surface reflective index) content to reduce the heat island effect. Glass has high SRI index. So it reflects more sunlight away and what could have entered the building unhindered gets caught and converted into energy by the SPV cells. So another LEED credit point, credit interpretation could be sought jointly by the SPV as well as the Glass manufacturers.

Now as more and more buildings all around the world are opting for LEED Certification ( Leadership in Energy and Environment Design ), the above two credit points would fit well into the scheme of things. But this may not be enough to reduce the cost of  BIPV. Therefore we can adapt the idea which I have explained (in the article – Green Business Ideas : Cheap Solar Power is possible  ) earlier to manufacture cheaper BIPV’s  and yet creating space for newer research & development. Therefore what NEERI published as a problem can be solved by scientific ways and high-end engineering which follows the basic principles of Sustainable Building Design. And who knows one day we may have enough BIPV clad Green Buildings just as the above French building ( click on image ) which would help further reduce the enormous Carbon Footprint each City has, to make a safer Earth with better business ideas.


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