[RE-wrenches] PV powered music festival

[R Ray Walters]

Solarfest in Taos had a solar powered stage for years, so it definitely can be done. I've been into sound stuff lately, and I can say the loads are extremely variable.
I have a 600 watt rated amp, (class D design) that I peaked at 270 watts input and averaged about 150 watts while I was testing with a very low frequency signal.
I used a Kill-a-watt meter for the test, and the amp's clip light came on. 
I also tested a class A amp (much less efficient) but I found the same thing: I never could get the input watts even to half the rated output of the amp.
No load draw was about 20 watts.

I'd start at having enough inverter surge power to meet all the amps cont. rated output. You'll also want enough battery to hit the surges on the bass notes. (pretend its a well pump)
Car audio guys know that more battery = more boom.
You should be able to get some idea of the loads from the generator size that worked before, also.
Find out how many bands will play each day, and approx how long their sets will be to get KwH/ day.

Sinewave is mandatory, although the Taos Solarfest used a pair of Trace SW4024s as I recall.
The rest of the system was 8 L16s, an 8000 watt generator, and about 1000 watt array (again based on my foggy memory)
This wasn't for the main stage, but a secondary stage that worked well for maybe 5000 people.(their bass was a bit wimpy though. Might want to go with more battery)
I also recall that this was a trailer mounted rental unit from Sacred Power in Albuquerque, so they may consider some kind of leasing/ rent to own arrangement.

R. Walters
ray at solarray.com
Solar Engineer




On Apr 27, 2011, at 5:15 PM, boB Gudgel wrote:

> On 4/27/2011 3:51 PM, benn kilburn wrote:
>> 
>> Wrenches,
>> I have been asked about sizing PV systems for a couple different music festivals that have been run solely off of generators in the past.  The problem i'm having is determining the energy consumption of music/stage (amps, speakers, lights, etc...?) loads as well as concession.  The organizers have never considered the kwh of electricity used and it has never been metered.  I believe the attendance of one festival is expected to be in the range of 5000 and the other closer to 15000 over the course of a weekend.
>> 
>> Do any of you have any experiences in this area?  How were the loads determined?
>> 
>> No doubt that generator back-up will still be needed, to what extent, will be determined.  So what we're looking at would be a temporary off-grid PV system with generator back-up...
>> 
>> Any suggestions on how to proceed with this one?
>> 
>> benn
> 
> 
> You might want to check the guys out from this article from a year or two ago.
> I think it's just the kind of thing you're looking for.
> 
> 
> http://www.prosoundweb.com/photos/category/C17/
> 
> 
> Four (4) pacific northwest companies  made some of the products for this tour including the mixer board.
> 
> boB
> 
> 
> 
> 
> 
>> 
>> DayStar Renewable Energy Inc. 
>> benn at daystarsolar.ca
>> 780-906-7807 
>> HAVE A SUNNY DAY
>> 
>> 
>> 
>> 
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