Swept area
The Excel has a blade diameter of 7.00 metres. This means it has a swept area, or capture area of 38.48 square metres. This is all important when comparing wind turbines, since it directly relates to the amount of passing wind energy
the turbine blades can intercept.
Excel power output curve
The graph below shows the power produced (in watts) for the Excel at different wind speeds, based on
data supplied by the manufacturer.
The green line shows the actual output that the wind turbine achieves at the given wind speed,
according to the manufacturers.The dashed line in the graph shows the theoretical maximum energy that this turbine could extract from the wind,
according to Betz's Law (59.3%). At a typical wind speed of
5 m/s, the Excel is extracting
880 Watts of power from the wind, which is an efficiency of
29.74%.
How efficient is the Excel?
Wind turbines can only convert some of the energy in the wind into electricity. The graph here shows how efficient the
turbine is across the range of wind speeds you might get.
The orange line in the above graph shows the efficiency ranging from 0 to 1. The grey line is the previously mentioned maximum efficiency - The Betz Limit. If this limit is exceeded, the manufacturer's claims are not to be trusted!
While these graphs give an indication of the instantaneous power and efficiencies you might expect from the
Excel turbine, working out annual power production is more complex.
Read more about the
Power Predictor
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