Gridtek 10 islanding with outback? [RE-wrenches]

[Geoff Greenfield]

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Thanks for doing the math for me (and as a third party for my customer...)
He really thought he could "make it work..." and the customer is always
right  ;-)  (ahhhhh diplomacy... THAT should be in the NABCEP scope...)

Other developments - Pieter at Bergey pointed out big differences in Gridtek
VS SB, and also inferred that SB/outback marriages have been successful
based on luck as much as anything else... I don't think we will risk letting
the smoke out of that box.  My current plan is to swap the gridtek for the
transformer/VCS-10 and put in a traditional 48 volt system.

FYI - this customer (on his own) salvaged and rebuilt a forest service fire
watch tower and then klugged a mast to put the 10K on... Still up after 3
years.  What a view... below is his photo album - definitely not a typical
job.

http://community-2.webtv.net/Karma1955/FireTower

For a brighter energy future,

Geoff Greenfield
NABCEP Certified Energy Practitioner

THIRD SUN SOLAR & WIND POWER Ltd.
340 West State Street
Athens, OH 45701

www.third-sun.com
(740) 597-3111

-

Date: Wed, 27 Apr 2005 21:39:08 -0700
From: David Katz <david at aeesolar.com>
Subject: Re: Gridtek 10 islanding with outback? [RE-wrenches]



Geoff,
There is a problem with load shifting with batteries. The batteries will
cost $0.15 to $0.25 per kilowatt hour if they are well taken care of and
more if they are ruined early, so he cannot win. If the customer goes
with a low cost battery like a Trojan L16, each battery can discharge
about 1 kwh per day if cycled to half discharge. At that rate they would
be good for 5 years maximum, which is 1825 kilowatt hours per battery.
$200 / 1825 = $.11 / kwh. You will also lose 10% in the batteries and
20% in the inverter. $.11/.7 = $0.16 per kwh. He would be better off
with the 1.5 cents per kwh from the wind and no batteries.
Cheers
David
David Katz
President, AEE Solar
formerly Alternative Energy Engineering
1155 Redway Drive - Box 339
Redway, CA 95560 USA
(707) 825-1200
(707) 825-1202
email: david at aeesolar.com
web: www.aeesolar.com


Geoff Greenfield wrote:

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>
>Thanks for the reply - also (obviously) I could approach this with an SMA
>sunny island (right? lords of the red box?)
>
>Further conversations with the customer have shed more light on the
>situation. Instead of (as I assumed) being motivated by the value of having
>stand by power during outages and a desire to max efficiency/production
>during normal operation, the request for batteries is based on something
>else entirely.  The rural co-op has let him go pure bi-directional net
meter
>for 3 years due to lack of policy and luck... they have now installed
>computerized meters and sell him power at 10.6 cents and purchase it at 1.5
>cents.  On average, his wind offsets 60% of his use.  he wants to "load
>shift" (?) with a batt-verter system set up to power most of his 120 loads
>from the batts and charge from the grid/wind AC...  needing some sort of
>control to charge when the wind is exceeding household use, and obviously
to
>maintain the batts at some minimum should the wind hit the doldrums...
>
>A design challenge for sure!
>
>
>For a brighter energy future,
>
>Geoff Greenfield
>NABCEP Certified Energy Practitioner
>
>THIRD SUN SOLAR & WIND POWER Ltd.
>340 West State Street
>Athens, OH 45701
>
>www.third-sun.com
>(740) 597-3111
>------------------------------
>
>
>



------------------------------



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