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Comparison between Wind-energy and Photovoltaic Solar-energy


a)     Relationship of investment to production of electricity:

Wind: Production per day for investment of 1 lakh rupees = 11 kWh

Pv:    Production per day for investment of 1 lakh rupees =  4 kWh

b)    Net energy-balance of  device: 

Wind:  For each kWh invested to construct windmills one gets 7 kWh

Pv:    For each kWh invested to manufacture Pv panels one gets 3 kWh

c)     Net environmental benefit in relation to investment:

Wind:  For investment of 1 lakh rupees the net green current output is 9.35  kWh

Pv:     For investment of 1 lakh rupees the net green current output is 2.60  kWh

Conclusion:  Wind energy is much cheaper then photovoltaic energy, and to manufacture solar panels requires huge amounts of electricity. Therefore the actual benefit to the environment from wind energy is around 4 times as much as from photovoltaic energy.


Therefore, Varuna has invested first into wind energy. Auroville produces double the quantity of electricity that it consumes, in the form of green energy from its 4 wind-generators near Coimbattore.


However, if we are to further help the environment, we have to look also at the other big energy producer: Photovoltaic. The reason is that in Tamil Nadu we have reached saturation of the electricity grid with wind energy. Nearly 20% of Tamil Nadu’s electricity is now produced by wind generators. More than that is not possible. Nearly all the energy is produced in the wind season June to September, and at that time the grid in the wind areas is overloaded. Already now up to 30% of the produced wind energy cannot be absorbed by the weak grid, and is going to waste. So it makes no sense to put up more wind generators in Tamil Nadu.


Photovoltaic plants, especially in the wind areas near Coimbatore, would be an ideal outbalance for the one-sided input of green wind energy:

a)     During the windy monsoon season, when most of the wind energy is being produced, the Pv plants would produce less energy due to cloudy skies, and so would not overheat the grid.

b)    During the wind-scarce dry season the Pv plants would produce their maximum of energy, since there are hardly any clouds at that time.

c)     TNEB has the problem that during 3 months of the year when the wind blows fast the substations for the wind generators are overloaded, while during the rest of the year the substations are functionless, since hardly any energy is produced by the wind generators. But still the substations have to be manned. If during the windless season there would be Pv energy flowing through the substations of the wind areas, then the cost factor for the wind substations would come down drastically. The substations are there anyway and could be used by both wind and Pv.

d)    Pv electricity is being produced at times when there is higher consumption of electricity. During the day, when it is hot, when more air-conditioners are running, when the factories are consuming power, at that time the Pv electricity is being consumed, while wind-energy is produced also in the night when there is hardly any demand. The coal power plants, which are producing nearly 75% of Tamil Nadu’s electricity produce round the clock the same quantity of electricity. Since during the day there is much more demand for electricity than during the night, there is too much electricity at night, and not enough during the day. Wind energy produced during the night is adding to the over-production during the night, and only the wind energy produced during the day is really needed. With Pv current it is exactly the opposite: the production pattern is quite parallel to the consumption pattern. 

e)     There is a strong tendency that the cost price of photovoltaic electricity is coming down. This price is coming down also due to the fact that photovoltaic panels are being produced in huge quantities. Therefore, even if we invest in photovoltaics now, while it is still unproductive in terms of the general electricity costs it may be that it will help the worldwide Pv industry to come down in its prices to finally match the general cost price. This argument is however doubtful. The manufacturing of Pv panels depends fully on dirty, cheap energy. The moment one would manufacture Pv panels with expensive clean energy, the price would shoot up. One of the world’s biggest manufacturers of silicon for Pv panels is Wacker Chemie in Germany. The manufacturing of silicon for Pv panels is so energy-consuming that Wacker has an energy consumption figure double that of the whole city of Munich. Due to the fact that Germany is now trying to go more for green energy, the energy prices are going up in Germany. Therefore Wacker has declared that it becomes difficult to generate profit in Germany. In Germany we have only about 12% of green energy till now. And already with this ratio of green energy in the German grid, the production of Pv silicon becomes impossible. Once we would have 50% or more green energy in our grid, the price for electricity would become so expensive that the prices for Pv panels would also shoot up. So the question is: Should one support the manufacture of a so-called “green energy-producing device” which totally depends on cheap dirty energy for its own manufacturing?

f)      Once the Tamil Nadu grid would be re-stabilised a bit by a massive input of Pv electricity, the wind sector could maybe start to add a bit more capacity, which is not really possible right now.  


In any case, the Varuna team has come to the conclusion that it makes more sense right now to start investing in solar energy, especially into Pv panels, than to go on investing in wind energy.