[RE-wrenches] FW: AC (only) Diversion

Carl Emerson Carl at solarking.net.nz
Mon Oct 15 17:35:45 PDT 2012


Hi there,

 

Just to clarify, we are talking about a battery-less grid tie system.

 

We want to have the choice to divert the AC available for export to an AC
load for example a pump or a thermal store.

 

The reason for this is that the tariff for export may be only 10c and the
unit cost to import 20c.  (net-metering not available)

 

Further to this, the tariff changes depending on the time of day.

 

Financially it is often a better option to use the excess power locally on
site rather than to sell back to the grid.

 

Is there an off the shelf unit that will sense when the generated power
exceeds the loads and can divert the power that would have been exported to
a local load?

 

I have figured out a way to do this cheaply but need to know if I am
reinventing the wheel.

 

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

 

  _____  

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Drake
Sent: 16 October 2012 1:04 a.m.
To: RE-wrenches
Subject: Re: [RE-wrenches] AC (only) Diversion

 

You could use Morning Star relay driver to control the AC dump load. I have
one for my system, but have not yet installed it, but have programmed it on
my computer.  If it works as designed, it should be perfect in conjunction
with a relay. 



At 04:42 AM 10/14/2012, you wrote:

Hi there,
 
Is there an off the shelf low cost product that will divert exported
energy to a load?
 
I have put thought into this and have a simple solution but need to know if
it is worth while marketing it.
 
 
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 <http://www.freepower.co.nz/> 
 

  _____  

From: re-wrenches-bounces at lists.re-wrenches.org [
<mailto:re-wrenches-bounces at lists.re-wrenches.org>
mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Chris Mason
Sent: 13 October 2012 2:17 p.m.
To: RE-wrenches
Subject: Re: [RE-wrenches] AC (only) Diversion
 
It is called a reverse current relay, use it to to run on a water heating
contactor when there is current to the grid.
This is a problem I have struggled with for ages. We do not get credit for
export so I have been looking for a good use for free electricity, have not
found one yet.
On Fri, Oct 12, 2012 at 3:36 PM, Nathan Stumpff <Nathan at arcticsun-llc.com >
wrote:
Wrenches,
 
We are working on the design for a system where we will be using grid-tied
wind and solar but will not be able to net-meter the project (we can
interconnect but the meter only runs one way.) Anything we use on site is
worth 100%, any production that goes back to the grid is lost forever to the
customer. What we would like to do is monitor all solar and wind production,
monitor all usage, and then be able to dump every watt-hour of over
production as heat, there is plenty of (thermal) storage capacity.
 
If this were a battery based system I know how I would approach this and
what equipment I would spec, but so far I am having a hard time coming up
with a  solution. Anyone have any suggestions for products or strategies in
this case? Something like an eGauge with programmable PWM relay outputs?
 
Any thoughts or suggestions are most appreciated,
-Nathan
 
 
--
Nathan J. Stumpff - Arctic Sun, LLC
NABCEP Certified PV Installer #091209-175
NABCEP Certified Solar Heating Installer #032412-14
nathan at arcticsun-llc.com
Office: 907/457-1297 <tel:907%2F457-1297> 




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