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 emer...@freepower.co.nz Web www.freepower.co.nz _____ From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@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 emer...@freepower.co.nz Web www.freepower.co.nz <http://www.freepower.co.nz/> _____ From: re-wrenches-boun...@lists.re-wrenches.org [ <mailto:re-wrenches-boun...@lists.re-wrenches.org> mailto:re-wrenches-boun...@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 <nat...@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 nat...@arcticsun-llc.com Office: 907/457-1297 <tel:907%2F457-1297>
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