Miniature Solar Array
Peter Doorn
View of completed array and close up of internal components.
Summary
In today’s green movement one of the major sources of clean, renewable energy is
solar power. Much of the solar energy collected is done through the use of large arrays of
solar panels, either on solar energy farms or as stand alone arrays used by individuals to
power their homes. These arrays are large, bulky, and, for the most part fixed to a
permanent base. They do not provide any sort of portability or ease of use to the end user.
The original idea of this project was to create a small portable array that could be taken
on camping trips or to the park to provide green energy on the go. To reduce the project
to a more manageable scope, the end prototype was designed to provide a proof of
concept for the use of a miniature array; showing that a small array could be created that
autonomously adjusts itself to the position of the sun.
The goal of this project is to keep the panel facing the strongest source of light in
order to maximize the output of the panel. These include first and foremost the ability to
turn itself toward the sun. The prototype must also be able to operate without user help; it
must be able to be turned on and left to perform its tasks. It needs to be sufficiently stable
and durable while still weighing as little as possible. Keeping the weight down increases
the portability of the unit. Finally, the sensors used must be capable of sufficient
sensitivity to allow for accurate and correct readings of the amount light reaching the
panel.
In order to meet these requirements several concepts were considered. The
favorite concept among the original set had the panel being mounted on top of a simple
tripod. This concept allowed for two axes of rotation for the panel and for the panel and
motor assembly to be easily removed from the tripod so that it could be collapsed and
carried easily. Other concepts included using a tilting table that could be operated along
two axes using motors and featured collapsible legs to improve portability. A third
considered concept was a simple one axis swinging array that had almost no portability at
all. The forth concept used extendable struts to raise and lower each corner of the panel
so that it could face the sun. This concept also had very little portability. Each of these
concepts were designed to make use of either a microcontroller or a custom made logic
circuit to read the light sensors and move the panel accordingly.
The final design for the prototype ended up being a mix of the first and third
concepts. The final design included the forth concepts one axis of rotation, east-west, on
a simple base but made use of the first concept’s movement mechanism and has a similar
support structure for the panel. The main structure of the final design is made of acrylic
panels and uses a single unipolar stepper motor to achieve movement. The ambient light
sensors used are sensitive to the full visible spectrum and the information from these
sensors is processed and used to operate the motor using an Arduino Duemilanove
microcontroller with a motor shield. It is also designed to use both the panel and backup
batteries to power the system.
The final prototype is capable of 360 degree rotation and operates without human
interference other than the initial turning on of the system. The movement it not as
smooth, precise, or complete as desired but it is acceptable for the prototype. The overall
structure is slightly top heavy but is otherwise stable and the frame is fairly durable. The
response from the panel is not as expected and the system relies on the batteries or other
DC source as the primary source of power.