Rock:
The GRID tied inverters do like to have high voltage, the 120 volts types like 400 volts, the 230 volts types around 600 Volts, because the electronics need to feed the current with voltages higher than the peak volts of the GRID and in addition being capable of doing it with the GRID under higher than normal volts.
All of then need to work under the MPPT power to optimize the power output under high voltage ranges.
In principle, there is a circuit that take the lower input voltage of the generator and converted to the 400 or the 600 volts, then the AC section supplies the energy to the GRID under MPPT conditions, even if the power is at peak.
Most of them have the problem that if the voltage is higher than the 400 or 600 DC volts they may disconnect which may cause that the wind mill over voltages further if the system does not have another circuit to fold the voltage to the desired level or a ballast controller to maintain the output at the maximum allowed voltage.
The generators should be designed to produce high voltage at the peak power, like 400 or 600 DC Volts at furling point.
This way the generator can produce with an efficiency that could go as high as 90 % and no problems with the stator heating, from the normal (old technology of the late 1880's + years) where the generator output voltage is "clamped" by the battery bank with an efficiency that may go to 43 to 50 %.
I have been promulgating the high voltage concept with electronics to bring the voltage down to battery levels.
Battery charging with high voltage and a charger controller with MPPT profile can attain around 85 % efficiency versus the 50 % of the OLD technology.
Nando
