NTREG Member Projects - Solar Trailer
(Dan Lepinski, designer, builder, and owner.)

As told by Dan Lepinski:
In April 2001, the City of Dallas, Texas held Earth Day at White Rock Lake Park. Due to the number of straw bales in use, the City prohibited open flame of any type in the park, so food vendors brought electric cooking equipment - and everyone plugged in. The overload that resulted tripped the main circuit breaker for that area of the park. Food quit cooking, presentations stopped, and the sound stage went silent. Thus was born an idea .. to provide future sound stages with totally independent, solar-derived power. What better way to celebrate Earth Day than to use the sun's energy for such a key aspect of this event?

Solar panels were assembled, batteries purchased, and inverters were donated by Exeltech. In 2002, the Dallas' Earth Day sound stage was powered by 100% solar electricity. The equipment performed flawlessly. This was the first time in the State of Texas where a public sound stage had been totally powered by the sun.

In September, 2005, Hurricane Katrina devastated the Gulf Coast. Volunteer first responders (members of a local police department) found themselves in desperate need of portable, reliable, fuel-free power, and asked to use the solar equipment for their property- and life-saving efforts. Four systems were requested, but only two existed. Two more were hastily built, and all four systems were taken to the affected areas in a horse trailer. The systems were returned to me six weeks later, some the worse for wear, but basically intact, and still completely functional. Words from the grateful police officers were simple. "Thank you. It saved lives."

Over the next several years, the equipment was used for a variety of purposes .. from Earth Day sound stages to powering emergency communication equipment. However, the "erector-set" nature of the systems made set-up and take-down very time consuming and difficult, especially for one person.

Thus was born an idea. The Solar Shuttle solar trailer is the next generation, and a major upgrade from the old system. With 50% more solar panel wattage, double the battery capacity, and 12,000 watts of sine-wave inverters on board, the Solar Shuttle serves a multitude of needs. Its primary purpose is educational, to showcase a full-size portable photovoltaic system. When not powering environmental or educational events, the Solar Shuttle is available to provide fuel-free, maintenance-free electricity for emergency communications to Search and Rescue Teams such as Texas Task Force One, public events such as the Plano Methodist Hospital Cancer Research Center Bike Race and Marathon Fund Raiser, the Regional Boy Scout Jamboree held annually in Irving, Texas, ham radio operators "Field Day" simulated emergency communications exercises, and many other functions. Since 2010, the Solar Shuttle has traveled through more than 20 states, providing power for more than 200 events, both planned .. and emergency-related. The predecessor system to the Solar Shuttle saw service for 9 years at more than 100 events, and performed flawlessly every time. When the old system was retired, the solar panels and other usable items were donated to Habitat for Humanity to continue providing power for others - which they'll do for the next 25 years or more.

Since 2010, the Solar Shuttle equipment has continued the flawless record of reliability of the predecessor systems. In all manner of service, whether educational, public event or emergency-use-related -- it too has been 100% reliable. This is the dependability of the sun.

For anyone interested in the technical details:
The trailer is a custom Wells Cargo 6' by 12' V-nose "Road Force" fully enclosed model, equipped with optional electric brakes. Wells Cargo was selected for the construction quality, and for the special "Tor-flex" axle that provides an exceptionally cushioned ride for the solar panels and electronic equipment.
Ten Sanyo HIT215N, 215 watt solar panels are mounted on the outside. Five are located on top, five more on the "driver's side" of the trailer. Output wattage of all PV decreases in hot weather, sometimes significantly. Sanyo PV are much less affected by heat than any other PV. They are also more efficient at converting sunlight into electricity than other PV on the market, no matter what time of day. When area is very limited, such as on the trailer, every watt counts. The Sanyo PV came out ahead of all others in that regard. I've seen more than 2400 watts being generated by the Sanyo PV, which are rated for 2150 watts. They are truly premium photovoltaic modules!
Eight, six-volt, 420 amp-hour Rolls-Surrette batteries provide more than 20 kilowatt-hours of storage. Rolls-Surette batteries are the best quality available. Rolls offers a seven year warranty, attesting to their faith in these batteries. The batteries, connected in two independent 24-volt configurations can be used separately .. or at the flip of a switch can be connected as one large system, doubling the battery capacity for one inverter.
Battery charging and maximum power point tracking are accomplished with dual Blue Sky Energy SB-50 Maximum Power Point Trackers. These units maximimize the harvest of energy from the Sanyo PV by up to 35% compared to directly connecting the PV to the batteries. I've seen more than a kilowatt being transferred from the solar modules to the batteries. The SB50 barely get warm. They are remarkably effective and well-built devices (made in the USA!).
Two Exeltech 5,000 watt inverters provide 120 volt pure sine-wave electricity for the most sensitive and demanding loads. The inverters can used individually, or simultaneously. Two separate 1,100 watt Exeltech sine-wave inverters provide additional power and serve as back-up to the large inverters. The smaller inverters can also be used independently for small loads. Total output of all inverters is 12,000 watts continuous .. and up to 25,000 watts peak. Made in America, Exeltech has been manufacturing inverters for 20 years. Their units, which provide pure sine-wave power, are among the most reliable in the world. They are rated for their full rated output 24/7. Audio engineers at events consistently rave about the clean and stable power from the Exeltech inverters .. often stating it's better than any power they've ever used from ANY source - inverter OR utility!

If by now you've noticed two totally separate solar electric systems designed into the trailer, you're correct. Dual systems provide total redundancy for enhanced reliability when the solar trailer is used to provide power during emergency situations.

I wish to publicly thank all sponsors involved with this project:

  • Exeltech
    Two 5,000 watt sine wave inverters and two 1,100 watt sine wave inverters.

  • Texas Instruments
    Sponsorship of the photovoltaic modules used on the trailer.

  • Blue Sky Energy
    Two SB50 Maximum Power Point Trackers/Charge Controllers with Remote Digital Display and Battery Temperature Compensation.

  • LI-COR Biosciences
    LI-200 Pyranometer (measures intensity of sunlight).

  • APW/MayVille (now Optima-Stantron)
    Rack mounts for the Exeltech inverters, Blue Sky Energy MPPT/Charge Controllers, and other hardware.

  • W & W Silkscreening
    Vinyl wrap and exterior graphics for the trailer.

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Solar Trailer - Phase 1 - The Preliminary Work



The trailer the day of purchase.
At its new home, waiting for solar panels.




The "passenger" side of the trailer.
Five solar panels will be on the opposite side.
A 32" wide door makes for easy access.




Inside looking forward.
The motorcycle chock has been removed.
View from the door to the rear.
The trailer has "barn" doors.




3/4" plywood and 150 lbs of steel reinforcing.
Solar panels on the trailer exterior need the support.
Both sides of the trailer were strengthened.
Walls and ceiling will be covered when finished.



Even the nose was reinforced!




Solar Trailer - Phase 2 - Solar Panels & Electrical Equipment Installation



2,150 watts of solar panels being installed.
Five solar panels each on the top and side.




Shield protects the solar panels while in transit.
It will be painted to match the trailer.
Battery boxes and inverter racks.
A workbench is in the background.




Cables from the solar panels.
Reinforcing steel and plywood are visible.
Solar panels installed. Graphics are next!




Solar panels deployed.
They can be tilted from totally horizontal...
...to completely vertical to follow the sun.




A more typical position for the solar panels.
The "business end" of the electronics.
Flooring and a ceiling are being installed.
One more 1,100 watt inverter will be added.


Debut of the "Solar Shuttle"at NTREG's March 13, 2010 meeting.
Graphics and mag wheels now added. A few cosmetic items still yet to do.
(Several NTREG members posed with the trailer after the meeting.)




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