Rebecca Bussiere
Michael Johnson
4/27/2010
Site Evaluation Group
Site evaluation
consisted of troubleshooting various systems around the island under the
guidance of Gary. Our first day on the island brought us to a sustainable herb
farm that was having difficulties with their solar powered irrigation system,
and their hybrid wind and solar set-up. Our goal for the week was to fix the
poorly wired PV and wind system, and set up the irrigation system in a more
effective way. The same day we traveled to a private residence that was
interested in installing a micro-hydro system. The group had the opportunity to
evaluate the amount of energy that could be drawn from the river. Through these
two projects we learned how to effectively troubleshoot various renewable
energy systems.
The private residence was already using the river for irrigation water, but was looking for the next step in off-grid energy reliance. We were there to evaluate the potential of a micro-hydro system for the home. This was done by at first measuring the head of the river. Using a five foot stick and a level we were able to determine the head, or height, of the stream. One person placed the level on the stick, and sighted down the instrument, making sure it was level. Another person would move to the location that the person was sighting and mark the spot. This would be a measurement of five feet. The process was then repeated by moving the sighter to the marked location. By this method, the group measured the head of the stream to be 50 feet. The flow of the stream was then estimated to be 100 gallons per minute. To determine the energy potential of a micro-hydro system one would multiply the head by the flow and divide by ten. This gives the energy in watt hours. For this system then the energy provided would have been 500 watt hours. Multiplied by 24 hours a day this would have been 12,000 watts a day that this system would be putting out. This was more than enough energy to power the home.
The site evaluation group also troubleshot an off grid wind and solar unit
system which has not worked in months located on a farm which helped educated
the community of farming practices, showing an example of sustainable farming
options. First it was determined that the battery needed replacing as well as a
majority of the wireÕs throughout the wind system as they were the wrong size
for the equipment used. To determine the size of wires need we simply measured
the distance the wire traveled from the wind turbine to the batteries inside
the building. With the replacement of the wireÕs a kill switch was added to
allow for the option of turning the wind turbine off 
in the occurrence of a storm. Another mistake which was
discovered throughout the hybrid solar and wind system was the placement of the
wind turbine wires through the solar charge controller, something which was
unnecessary for the system. A painful lesson our group learned in the process
was that the backwards installation of a battery to an inverter was a quick way
to fry the inverter deeming it necessary to replace. With a new inventor
the entire system worked perfectly allowing the small dwelling to have enough
power for a few lights and a small cooler if wanted. An observation we were
quick to point out to the owners before we left was concerning the placement of
the photovoltaic panels. The panels had been placed on the north facing side of
the structure when, considering the island is north of the equator, the panels
should have faced south. On the same property we worked towards re-piping
a pump unit which pumped water from a spring up to a elevated garden plot to
water the garden. The water holding tank was cleaned out and moved closer to
the source of the water as its original placement was at an elevated level.
We then measured, cut, glued and installed PVC pipe from the new location to
the pump, showing the owners where to install a water filtration system to
avoid clogging the system. While we were unable to finish the entire project we
feel confident that the work which was accomplished will allow the owners to
quickly finish any necessary work and once again have water pumped to their
gardens
