[RE-wrenches] wrenches] PV powered music festival

Sat Apr 30 21:41:51 PDT 2011

Sorry about getting into this discussion so late.  Internet has been down for 3 days at my remote off-grid home due to equipment failures at my wireless provider.  I take care of maintenance of the off-grid mountaintop transmitter site but the problem wasn't there. 

SolarFest in Vermont has a hybrid grid tie and off grid power system using 6 VFX3648's for the stage lighting and 2 GVFX 3648's for stage sound and recharging the batteries overnite.  The 6 off grid inverters have grid power available but we have never turned on the breakers. They have run only as off-grid inverters powered from the shared battery bank.  This is a 3 day Festival with the stage drawing power all day and evenings with the heavy loads during the evening shows.  We have experimented with various battery sizes and after the first year with 96 Interstate L16's, we have scaled back some to 56 or 64 batteries.  Our peak loads have hit 21kw for lighting but this past year it was usually peaking at about 16 kw as more LED lights are being used.  The light show is spectacular.  The sound usually peaks under 3kw.  The two grid tie inverters work pretty hard as they are constantly selling or buying from the grid depending on the time of day and loads.  The battery would probably keep the show on during a major power outage for about 3 or 4 hours at peak demand with the 56 batteries.  We have the grid tie inverters programmed to charge the batteries at a modest rate and they are essentially passing thru and charging the batteries during the heavy stage loads, mostly selling during the day when the 4 racks of PV's (8,000 watts) are producing power and stage lighting loads are down and after the show is over for the night, it usually takes until about 4 to 5 am to get the batteries back to full.  Our pull in from the grid at night is about 50% of what we are using, keeping the grid tie inverters from being overworked. We usually hit 50% or a little lower at the end of the evening light show.

 Our system essentially is a grid tie with significant backup and balancing capabilities. We also have 1 permanent top of pole rack (1440 watts) feeding the SolarFest office grid tie system with a GVFX3524.  Other power produced on site is a temporary 4000 watt direct grid tie feeding into the grid for as much time as we can keep the panels (on loan from various sources) and 4 or 5 stand alone systems running the box office and workshop tents.  We have a power trailer (the Solar Roller which originally powered the whole festival!!!) with 1200 watts now used to power workshop tents and then "put to pasture" directly feeding the 2 GVFX2648's the rest of the year to build up our credits.  Our 14 kw or so total PV (not counting vendors) is not enough for real time off-grid operation over the course of the day so we rely on some prevestival generation as well as post festival generation to net zero for the event.  We currently have enough kwhours acrued to run the festival for one entire weekend and still have our meter behind the zero starting point.  We often discuss trying to have the festival capable of being totally off grid but we would have to install a lot more solar and batteries.   I won't bore all of you with the disasters we encountered on the way to our beautiful, perfectly functioning power system.  I will be providing the story on the SolarFest website in our power section (when I find the time to write it).  For some photos of our system, check out www.SolarFest.org.

John Blittersdorf
CVSOLAR

Message-----
From: Exeltech <exeltech at yahoo.com>
To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
Sent: Sat, Apr 30, 2011 7:47 pm
Subject: Re: [RE-wrenches] PV powered music festival

Running a generator defeats the purpose of having a solar electric system on 
ite to provide event electrical power.
I've provided solar electricity at events for the past 10 years for groups up to 
8,000+ people.  All have been successfully done without a generator.
It's a good idea to have generator backup power for recharging batteries "just 
n case" .. the same with off grid homes .. but is best not to have to use it in 
he first place.

an

--- On Sat, 4/30/11, Carl Emerson <freepower at freepower.co.nz> wrote:
> From: Carl Emerson <freepower at freepower.co.nz>
 Subject: Re: [RE-wrenches] PV powered music festival
 To: "'RE-wrenches'" <re-wrenches at lists.re-wrenches.org>
 Date: Saturday, April 30, 2011, 6:33 PM
 Kelly,

 I have heard of it being done successfully in the Pacific
 Islands with
 Generator derived mains.

 Carl Emerson
 Free Power Co.
 Land line +64 9 473 4286
 Mobile +64 22 630 9689
 Email   emerson at freepower.co.nz
 Web   www.freepower.co.nz

 -----Original Message-----
 From: re-wrenches-bounces at lists.re-wrenches.org
 [mailto:re-wrenches-bounces at lists.re-wrenches.org]
 On Behalf Of Kelly Larson
 Sent: 1 May 2011 10:48 a.m.
 To: RE-wrenches
 Subject: Re: [RE-wrenches] PV powered music festival

 Hi Carl,

 You can't backfeed a generator.  I think it blows the
 voltage  
 regulator?  And the output is often too dirty to
 connect to.

 Here is a place for controls.  If one could control
 the loads well,  
 you could accommodate solar fluctuation.  But alas,
 until then, we can  
 stick to our battery backup, where the genny will back off
 when the  
 batteries are full-ish.

 Blessings,
 Kelly

 Kelly Larson
 Electrical Engineer
 NABCEP Certified Solar PV Installer
 ISPQ Master Trainer
 CA C-10 # 868189
 SolarKelly at asis.com

 On Apr 30, 2011, at 4:35 PM, Carl Emerson wrote:

 > Great discussion.
 >
 > Why not backfeed into the generator and reduce fuel
 costs?
 >
 > Carl Emerson
 > Free Power Co.
 > Land line +64 9 473 4286
 > Mobile +64 22 630 9689
 > Email   emerson at freepower.co.nz
 > Web   www.freepower.co.nz
 >
 > -----Original Message-----
 > From: re-wrenches-bounces at lists.re-wrenches.org
 > [mailto:re-wrenches-bounces at lists.re-wrenches.org]
 On Behalf Of  
 > Kelly Larson
 > Sent: 1 May 2011 9:16 a.m.
 > To: RE-wrenches
 > Subject: Re: [RE-wrenches] PV powered music festival
 >
 > Wow!  What an great discussion!  Nice
 documentation, Dan.
 >
 > I have powered part-solar, part-generator, part
 grid-powered events
 > for several years.  It's problematic.  Few
 have a clue how much power
 > and energy they use.  If they use to much it
 makes the electrician
 > look real bad.  I walk around on my rounds and
 check everything
 > regularly.  It's a big job.  Some of what I
 learned that hasn't been
 > mentioned (or much):
 >
 > ALWAYS have a genny on hand to cover anything Murphy
 throws in.
 > (...of Murphy's law)  A failure at a public event
 is hard to recover
 > from.  Size it to cover everything PLUS battery
 charging.  A dead
 > battery is worthless to you AND degrades the bank for
 future use.
 > When the music's loud no one will notice, (or turn it
 on over night
 > for recharge).
 >
 > Taking along a TED 5000 would be real helpful in
 figuring out what
 > uses what.  The TED is pretty versatile, and
 records the data, (but
 > takes a little figuring, so use it before the event).
 >
 > A clamp on ampmeter is an essential tool. 
 (Remember, most clamp on
 > ampmeters are AC only).
 >
 > Watch the extension cords.  They can easily be
 undersized and often in
 > poor repair.  In the past I've used big #10 SO
 cables to get power out
 > to where it will be used to address this.
 >
 > An IR temp gun or thermal camera can help keep quick
 tabs on what is
 > getting hot, which can be especially nice during
 headliners.
 >
 > Take the time to stand out front and educate about
 energy and
 > renewables.  Have fun with it!  Have flyers
 that list resources for
 > energy efficiency and energy conservation, as well as
 renewables.  I'd
 > love to have a meter with a big readout that says how
 much power is
 > being used with a running total of energy. 
 Project for the future...
 >
 > Blessings,
 > Kelly
 >
 > Kelly Larson
 > NABCEP Certified Solar PV Installer
 > ISPQ Master Trainer
 > CA C-10 # 868189
 > SolarWrench at asis.com
 >
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