Very good numbers. I've found their monthly "enlightener" that they send with each bill on line and found this interesting tidbit.
" if considering a PV system, know that not all contractors are the same. We are installing a model PV system at our main office so our customers can come to us with questions about PV systems a costs." They are very "pro-coal", and I think I'm getting used. This system will be nothing like a system a residential customer would have installed and will cost significantly more that a GDI system. Do you think they will mention this to their co-op members that inquire about PV? Jesse Sent from my iPhone On Jun 25, 2013, at 12:27 PM, "SunHarvest" <e...@harvesthesun.com> wrote: > Hi Jesse, > > If I read this correctly your customer is wanting to go off-grid during peak > hours. I recently went through this same thing with a customer. I received > feedback from an old SMA tech and some Wrenchers (thread titled "Battery > Back-up and Grid Tie"). Here's what I learned: > > 1. Inverters are more efficient at inverting than charging, anywhere from > 5-10%. Add to that about 10% transmission loss...you'll always have > significant energy losses associated with trying to put back that power that > you're drawing out during those peak hours. Energy loss = $$ loss. > > 2. Compare the utility peak kWh cost against the cost of cycling the battery > bank. Just for an example, let's say for a 48V system you're using 150Ah 12V > Trojan AGMs $2000 for 8 batteries. If the specs say those batteries, at 50% > discharge, get 1000 cycles in their lifetime, that's $2.00 per cycle. 300Ah X > 48V X 50% = 7.2kWh. $2/7.2kWh = $0.28/kWh. Add to that 20% round-trip > efficiency losses, you're up to $0.33/kWh. What else does daily, unnecessary > cycling add: Extra maintenance? Shortened life so probably should factor in > some replacement cost?... > > 3. Murphy's law says that the power will go out at the end of one of these > non-essential discharge cycles. Then what? > > Probably not worth it. > > Eric Stikes > SunHarvest > 530-798-3738 > ----- Original Message ----- > From: Jesse Dahl > To: RE-wrenches > Sent: Monday, June 24, 2013 8:50 PM > Subject: [RE-wrenches] Battery bank during peak times > > Hello, > > I was contacted by a local co-op about installing a PV system at their > office. At first they wanted a straight grid-tied system, and after they > received the bid they changed their minds and now want a battery based system > price. What they want now is a system that will allow them to draw the > battery bank down starting at 5pm during their peak demand time. Has anyone > worked on or installed a system of this type? > > > Thanks as always! > > > Jesse > _______________________________________________ > List sponsored by Home Power magazine > > List Address: RE-wrenches@lists.re-wrenches.org > > Change email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out participant bios: > www.members.re-wrenches.org > > _______________________________________________ > List sponsored by Home Power magazine > > List Address: RE-wrenches@lists.re-wrenches.org > > Change email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out participant bios: > www.members.re-wrenches.org >
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