The Dr. Robert Ervin Green Energy Learning Project
The Dr. Robert Ervin Green Energy project is the offspring of a very
ambitious idea to make Bangor High School run entirely off of green energy. Due
to the immense cost of this idea, the project was scaled down to make one
science classroom run off of solar energy. This classroom would act as a model
for classes throughout the Bangor School Department and would be available for
students interested in doing independent research projects. Two students leaders
(EF and NH) emerged early in the project, contacting BHS Science Department
Head Cary James to express their interest in researching the project. The
entire project was turned over to them, with Cary James and Dr. Simon Wesley,
the teacher of the classroom into which the system was going, as their
advisors.
The students researched different types of photovoltaic (solar energy)
systems, their size, cost, and the materials that would be used.The conceptual plan was presented to
Dr. Robert Ervin, Superintendent of Schools, who approved this plan and set a
date for the student leaders to present the plan to the Bangor School Committee
on June 25, 2008. The Bangor School Committee approved the project and funding,
paving the way for the students to contact ReVision Energy out of Portland,
Maine, the contractor chosen to install a photovoltaic system in the science
classroom. ReVision installed the system under budget in August 2008. The
system was fully operational by September 2008 and the data collecting website
was accessible in January 2009. [Project Timeline]
While financial and environmental savings accumulate, the impact on
learning is the most valuable outcome of the Dr. Robert Ervin Green Room as
students continue to use the photovoltaic system to do independent research
projects.
BHS Photovoltaic System- How It Works
The Bangor High School photovoltaic system is fairly simple
if you look at it in steps. One starts on the roof of BHS where 4 rows
approximately 25 ft long of solar panels are arranged facing the east with an
approximately 45 degree angle of tilt. These panels collect the sunlight and
convert it into 325 volts of DC (direct current) energy which is sent down into
the indoor part of the system located directly below the panels.
Because the
room the energy powers uses only AC (alternating current) energy, the 325 volts
DC then pass through two inverters converting them into 120 volts AC. The 120
volts AC then pass into a switch box which allows manual manipulation of where
the energy is used. The energy can go to three different locations:
The
system has 4 glass matte batteries that store energy that would be used to
power the room if no sunlight was available and there was a demand in the
classroom. These must always be full, and if they are not, the computer of
the system (talked about later) will send energy only to them until they
are full. The batteries are first priority.
The
second priority is the electrical demand of the classroom, lights,
computers, projector, etc.
Finally,
if the batteries are full and the classroom has no energy demands (July
through August) the energy is routed back to the school to be used in
other classrooms, or if the entire school is shut off, back to Bangor
Hydro Electric.
There are four switches in the switch box, and the fourth
one cuts the indoor computer system off from the outdoor panels for maintenance
etc.
After
passing through the switch box, the energy is directed into an inverter box
that acts as the brains of the system. It controls where the energy is sent and
is able to convert the 120 volts AC to 325 volts DC for use in filling the
batteries.
The
batteries are glass matte, meaning they give off no fumes and will most likely
last for about ten years if they are maintained appropriately. These are about
the size of golf cart batteries and are enclosed in a wooden compartment below
the rest of the wall mounted system.
Apart
from all of this, but connected to the two inverters and the “brain” is a black
and red switch that is the emergency disconnect for the entire system. If
needed, the entire system can be shut off in seconds, but generally this switch
is not needed as all live wires are enclosed in conduits.
Also
mounted with the system are the sensor box data collectors (each row of panels
is equipped with a sensor that measures sunlight intensity among other things)
and the Ethernet connection box.
