Ireland has very good wind resource, on open areas, hills and coast we can find places with average wind speed around 6m/s at elevation 12 meeter above the ground. On SEAI wind map you can see average wind speed at 50m above ground and above.
Before installation of wind farm wind resource assessment is done based on one year precise measurement on up to 120meters high met mast. For small scale wind turbines that could be done too, but most often we do not want to wait a year for wind measurements. There is few important factors regarding placing a turbine (prevailing wind direction, shadow and turbulence are the most important ).
To know how much energy your wind turbine will produce you need to know 2 things;
- average wind speed of your site (at the hub height )
- estimation of expected annual energy production (AEP), this can be done by independent test center or data sheet of wind turbine (manufacturers usually increase it ).
Below you see AEP for windspot wind turbine (4m rotor, 6kW max power of generator) from test center and from manufacturer
I hope that everyone understand that wind turbine is producing little power at small wind speed and higher power at higher wind speed. Power curve of the turbine describes that relation. Power curve also says about quality of the wind turbine (it's starting wind speed and maximum wind speed). Again power curve can be measured by independent test center of you can find it on data sheet. Examples below.