In response to The Grenfell Record article mentioned in our last blogsite post several people have contacted us for more information, mainly about the wind turbine. I thought there may be others who are interested in this as well and provide below some of the more curious learnings we’ve had to date.
Our battery set-up is 48 volts, made up of 24 X 2 volt batteries. The actual voltage has varied so far from around 49 to 56 which is quite normal. The wind turbine does not add any current to the batteries until and unless the voltage it generates exceeds what is currently in the batteries. So whilst the blades of the turbine (which span 1.8 metres) might be spinning this does not necessarily mean that usable power is being generated. The Weddin Shire does not theoretically experience wind patterns that support reliable wind turbine based power generation however it is amazing to us how often the wind speed is sufficient to see our turbine adding power to the batteries.
When the batteries are fully charged and there is sunshine the solar panel system goes into ‘float’ mode which basically means that it ceases to generate power, a bit like going into neutral in a car. The wind turbine controller acts differently. When the voltage from the wind turbine exceeds what’s in the batteries and the batteries are fully charged the controller literally burns off the surplus power via heating of resisters in the back of the control unit, a bit like a mini bread toaster. NB: The controller design, its location in the control room and installation arrangement is such that it is completely safe from a potential fire risk perspective.
At various stages when the turbine is gathering speed in response to increasing air movement (wind) there is considerable vibration. The tower arrangement in place is specifically designed to account for this. Some others who have purchased and installed small turbines have placed them on the end of sheds or houses and found that the units literally send tremors / shakes through the entire structure.
Wind turbines do not handle wind turbulence (disturbed air flow) at all well. This is why large wind turbines are generally on high towers with no trees or other structures nearby. In our case, we do have a large tree not far from the turbine to the west, and when we receive westerly winds the whole turbine unit on top of the tower at times actually rotates.
The guy rope tower arrangement is ingeniously simple and the turbine can be easily lowered to the ground and resurrected. The whole unit can handle very strong wind speeds; however the manual does suggest that the unit be lowered if it is known that wind speeds are likely to exceed 130 km per hour. The controller unit does have an ‘off’ switch and when this is flicked the turbine stops spinning courtesy of a non-moving-part breaking system that works electromagnetically.