Solar-Breeze - Robotic Solar Pool Skimmer

I had the chance, recently, to tour the largest photovoltaic rooftop installation in Arizona.  I jumped at the chance and climbed the ladder.  The installation is on the roof of the Cowley Co. Warehouse at 27^th Ave & Buckeye, not far from the State Capital building.

Our guides were Tom Lepley of Phasor Energy Company Inc. and Karl Schmitt, General Manager of Empire Renewable Energy, LLC.   Empire put the project together.  Tom was the lead engineer.

The scale of this project takes your breath away. 7,872 crystalline silicon modules (solar panels) cover 28,000 square feet of rooftop.  The array is held on the roof by its own weight and some ballast around the periphery.  There is no racking attaching it to the roof itself.  The wiring and conduit appear like leashes to hold it down but their only function is to take that harvest of solar energy  down to the invertor room where it can be changed into useable AC power.

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Pholtovoltaic cells, more commonly known as Solar Panels, are everywhere these days.  They are in big electrical utility installations, on the Solar-Breeze robotic pool skimmer, and on the calculator you carry in your briefcase.  We are very comfortable with Solar Panels but many of us have never even considered how they work.

Kyocera has an excellent educational website called "Solar Power Expo".  In pavillion 4, they explain the science behind the photovoltaic cell.  Follow this link to their website.  http://global.kyocera.com/solarexpo/solar_power/

Sand is processed into very pure silicon.  Impurites are added to specialize the silicon.  Boron is introduced to make P-type silicon  Phosphorus is added to make N-type silicon.  These two types of "doped" silicon  are combined to make a crystal semiconducter which has a permanent electrical field at the junction between the N and P type sections.



When the photons in sunlight hit the semiconductor, electrons are released at the junction and are attracted to the n-type semiconductor. This causes more negative charge  in the n-type semiconductor and more positive charge in the p-type, thus generating a flow of electricity in a process known as the “photovoltaic effect.”  By attaching a wire to both sides, the electron flow can complete its journey from the junction area to the N-type, through the wire, to the P-type and back to the junction, only to do it again and again.




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