[RE-wrenches] Mobile Solar power Center

[Exeltech]

This must be the season (year?) for solar trailers.

I've provided solar power for soundstages in the Dallas/Fort Worth area for nearly 10 years with a very manually assembled set of PV, batteries, and inverters (think "erector set").

I'm doing major upgrades to system this year, making everything much easier to use and display in the process.  All equipment will go inside, or on a Wells-Cargo enclosed trailer.

The trailer will contain two totally redundant systems.  In the event of a major failure in one system, the other would be immediately available.  I've never had a failure in the years I've been doing this .. but twin systems is a "reserve chute" .. just in case.

The design consists of 2300 watts in PV (1150 watts per system); two Blue Sky Energy MPPT charge controllers; 20 kW-H of sealed AGM battery; and two 5,000 watt Exeltech MX sine-wave inverters.  All equipment can be run completely independently as two separate systems, or be electrically tied together at any point at the flip of a switch to make one large 10 kW configuration.

Half of the PV will be mounted on the "driver's" side of the trailer; the other half will be on top.  All PV will be automatically positioned with an electrical linear actuator (with manual "awning crank" override should an actuator or the DC fail).  Once positioned, all PV will be fixed, not tracked.


Here are a few of my own observations from years of experience of powering outdoor events:

1) Soundstages are getting bigger and more power hungry every year.
   As Karl surmised, and I totally agree, 1 kW will not be adequate
   unless you're powering *very* small events.


2) Greater wattage gets drawn from the power system near the end
   of the day/event than at any other time.  "Highlighter" bands
   tend to be the last, and loudest on stage.  This high power
   consumption usually coincides with a time of day offering little
   or no sun sunlight.  Thus, a substantial battery system is
   required.  Cloudy weather plays into this as well.


3) Use inverters with the absolutely cleanest *sine wave* available.
   The slightest harmonic distortion can and does show up in the
   output audio of some equipment.  Voltage stability is also a must.
   Use inverters with very tight voltage regulation, and connect them
   to the audio equipment ("amplifiers") with heavy gauge extension
   cords.  Once again, Karl is right on target with his comment.

   Some sound engineers I've met have remarkably acute hearing,
   and notice everything about the power - whether real, or not.


4) Unless you have an unlimited budget for equipment, don't even
   think of powering their stage lights.  ('Nuff said...)


I too would very much appreciate any and all comments and suggestions.



Dan


P.S.
Karl .. for a self-proclaimed "hot water" guy, you're very well informed on the solar electric side of life.  Good job.



--- On Mon, 1/19/09, Karl Schwingel <karl at northwindrenewable.com> wrote:
> I did a large service job on a mobile stage/ solar power
> system trailer.  I can tell you lots of things _not_ to do. 
> solid wire.  vented inverter where truck spray gets in, no
> grommets where power cables go thru AL plating, etc.
> It's a little bigger than what you're proposing.
> 1.8Kw of unisolar and 1 VFX 3648 inverter.
> 
> it was the armadillo stage shown here:
> http://www.sustainablewaves.com/ourequipment.html
> 
> I did feel pretty good about getting the call Sat 7PM, and
> having 2 new sealed FX 3648's in  and the guys on the
> road by 3:00 Monday AM. 
> for your system I would go larger than a 1KW inverter, at
> least a outback or Magnum for larger power draws.  others
> can weigh in, but I'm not thrilled about any of the
> smaller battery based inverter offerings out there.  Are
> prosines still made?  you will want a sine wave inverter for
> the good power quality.
> 
> Just $.02 from a hot water guy.
> Karl