Solar Panels v Wind Turbines (part 2)

Even if you do not like numbers, figures and statistics you have to give these their due!
(Some claim Money makes the world go round, you know!).Wind Turbines and Solar Panels are not exceptions. This part 2 of the article reveals some insight as to the economics of the issue.


When you go deep into it the decision on the basis of economics should rest mainly on the life time cost of the equipment. (The initial cost is only a part of it).

• Both types can give useful service easily up to 20 years. While solar panels need almost no maintenance the wind turbines are not that far behind.

• Considering the case of a 1000 sq m building the analysis in simplified form would be as follows:

PV Panel Installation

The suns radiant energy on the earth is about 644 watts per m2 (after allowing for reflecting back and absorption).
• The installation has 1000 m2 of PV Panels operating for 5 to 8 hours a day
• PV panel power conversion efficiency =10% (min.)

The total yield therefore will be = 64 kw (apprx) per hour
Thus the monthly electrical energy yield =10,000 kwh (approx)

Assume the Cost of PV panel = euro3.12 per watt
The cost of PV panels for the building = Euro 200, 000 (aprrox.)
Therefore the estimated life cycle electrical power cost would be;
=200,000 /10,000 kwh X 12 months /year X 20 years
=Euro 0.83 per kwh

Wind Turbine Installation
Unlike in Solar Power it is somewhat difficult to predict the average wind velocity incident on the Turbine which determines the actual power out put.
(The power yield may increase by 8 fold for doubling the wind speed in an application).

• The required power yield is the same as for PV Panels ie.10, 000 kwh /month
• Use two turbines each with 50% capacity.
• The average wind velocity 32 km/h (maximum of 48 km/hr)
• Overall efficiency of the wind turbine=40%

When applying the general formula for the generated power:
= ( k )X (wind velocity) 3 X (swept Area) X (efficiency)

At 16 km/hr = 588 watts from each turbine
And Monthly electrical power yield = 729 kwh /month each

Therefore at maximum velocity of 48 km/hr the yield is = 16 kw
Therefore the anticipated power yield @ 32 km/hr wind velocity:
= 5,000 kwh /month each.

The power yield from two turbines would match the requirement of 10,000 kwh/ month.
The Cost for the total set of equipment would be approximately Euro39, 000

Energy Yield per 20 year period is = (2) X (5000 kwh/month) X (240)
= 2,400,000 kwh
The cost of wind power therefore = Euro 0.015 per kwh

Ridiculously low one might say! In spite of the uncertainties, the size of the building, the unpredictable weather patterns and assumptions, still the wind turbine seems a worthwhile consideration under certain applications like west coat installations and remote installations.

Social and environmental Issues

• The location of a wind turbine needs to be in an area where the local authorities have no objection to the aesthetics and the noise generated. The same tolerance should be available from the neighbors and of course the environmentalists.
• Environmentalists object tot the deaths of birds due to rotating turbine blades.

Happily both these issues do not apply to solar panels.

Significantly the variables in wind turbine selection, installation and performance are considerable in spite of the economy. To expect the ideal conditions is somewhat optimistic unless the data over a long period is analyzed carefully before taking the final plunge. The solar panels are free of this draw back. Hybrid installations with solar panels or with grid power therefore seem to be a good compromise where ever the cost can be justified.

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