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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Many Solar-Breeze owners live in the No-Snow Zone.  We welcome cooler temperatures but can still have dinner outside by the pool. 

Winter brings shorter days, and less direct solar rays.  When the sun hits pholtovoltaic panels at an angle of less than 90 degrees, they still function to turn solar energy into an electrical current, however the amount of current produced is less.  For the Solar-Breeze, this means shorter operating times as less energy is produced during the day and less charge is available on the battery during the night.

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There is a lot of buzz in the scientific media these days about batteries.  Specifically, what sort of batteries will we use to store wind and solar-generated electricity through long winter nights and cloudy or calm days.

The objective is to build 20MWh battery installations which would be sufficient to supply 2,000 homes for 24-36 hours.  Most of the attention is focussed on REDOX FLOW batteries.  Click on the link to read more about these batteries in Science Daily.

The Solar-Breeze robot uses a Lithium-ion battery. With a combined capacity of 12.5 watts, the unit's solar panels capture enough power during the day to both run the motors AND charge the battery.  As the sun reaches approximately 30 degrees from the Western horizon, Solar-Breeze shifts from operating on solar to operating on battery power.  Depending upon the amount of solar energy available to the panels during the day, the unit can run up to 8 or 9 hours into the evening/night.

The first version of the Solar-Breeze used Nickel-Cadmium batteries but the results were not as consistant or satisfactory as with the current Lithium batteries.  These rechargeable batteries are reliable for at least 1,000 charging cycles (days of use) and can be replaced to extend the working life of your Solar-Breeze.

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Forty minutes of sunlight contains enough energy to power global energy consumption for a year. So why isn't everything powered by solar? Read More...

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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