Mixing wind turbines with the tropics

Upgrades to System

The Project Curaçao box is still performing well after three weeks as of the writing of this article. As mentioned, I am planning a maintenance trip to Curaçao in September to work on the box.

The following upgrades are planned for Project Curaçao:

  • Replace the wind turbine – The broken mount box is not repairable. I am looking at two options. Option one is to purchase a new 50W turbine or buy a better (more expensive) wind turbine. Because the Raspberry Pi in Project Curaçao requires about 2W to operate, and the system is only generating about 0.5W at 15mph, I would need a significantly larger wind turbine.
  • Stiffen the turbine mount – I am going to add an additional cross-brace to the wind turbine mount (Figure 6). An additional horizontal brace will reduce the magnitude of the "Galloping Gertie" flexing caused by the wind.
Figure 6: An additional horizontal brace connected to tower will help reduce the motion of the wind turbine frame.
  • Add a vibration sensor on the turbine mount – I have purchased a piezoelectric vibration sensor (SEN-09197 from SparkFun [4]) to measure the flex of the turbine mount. I will be able to record the flexing in a database on the Raspberry Pi and read it remotely. I'm expecting to apply filtering to the data to detect anything useful, because the data is bound to be very noisy.
  • Add a loose strap over the top of the wind turbine – The strap will be screwed to the sides of the PVC turbine mount and to the top of the new wind turbine to allow the turbine to turn; however, the strap will not be long enough to allow the turbine to "pop out" of the mount (which destroyed the last turbine).
  • Add wind speed, wind direction, and rainfall sensors to the box – I am adding a passive anemometer, rain bucket, and wind vane to the box. This will allow me to record more weather data and better analyze system behavior and performance.
  • Modify the Arduino battery watchdog to record wind turbine current and voltage  – Currently, the data is recorded only when there is enough battery energy to run the Pi. This will allow me to record this information even when the Raspberry Pi is turned off and then transfer it to the Pi when the Pi is rebooted. The Arduino is designed to run all the time and is currently meeting that goal. I will also add a command that will read an instantaneous unregulated and regulated wind voltage and supply the information back to the Pi for the panel output.
  • Modify the angle of the solar panels – As expected, the solar power panels are not generating enough to power to run the Raspberry Pi all night. After some experiments in Curaçao, I concluded that I could more than double the solar power available to the box, thus allowing the Pi to run all night. I am considering mounting two solar panels on a stand and then rotating the stand with a servomotor to track the sun. The reliability of such a system in the tropics is definitely a concern.

These upgrades should address the problems the system has encountered so far.


The addition of a wind turbine to help power a solar cell-based Raspberry Pi and Arduino project has been a challenge. Although the electrical characteristics of the system are well understood and well designed, the mechanical parts of the design need to be reevaluated and mechanical stresses taken into account. The need for real-time data collection on the wind system was misunderstood and will be addressed in the upgrade. For more information about wind/solar power and the software for Project Curaçao, please visit the author's blog [5].


  1. "Sizing a Wind Turbine to Power your Raspberry Pi" by John C. Shovic, Raspberry Pi GEEK, Issue 4, 2014: http://www.raspberry-pi-geek.com/Archive/2014/04/Sizing-a-wind-turbine-to-power-your-Raspberry-Pi
  2. RasPiConnect: http://www.milocreek.com
  3. "Galloping Gertie" syndrome: http://en.wikipedia.org/wiki/Tacoma_Narrows_Bridge_(1940)
  4. SparkFun: https://www.sparkfun.com
  5. SwitchDoc: http://www.switchdoc.com

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