my biggest issue with bbgt systems is the inefficiency. my 4.3 kW (stc) array typically sells 2.8 kW. 5 years of tracking dc input versus ac output shows the obfx inverter runs around 87% efficiency. add battery maintenance and the extra wiring to split off "backed up loads" and the economics just dont work out. then, if you make this scenario even worse by adding battery cycling inefficiency and more frequent replacement... (to supposedly make money??) it is a no-brainer your customers "creative" idea is actually a hair brained scheme which will result in a net loss and increased consumption of resources. his money would be better spent on upgrading to more efficient appliances, improvements to his building thermal performance and conservation. i would not do this for a customer... and if they insisted, i'd let them hire someone else to implement these stupid (greenwashing) ideas for him. remember, you are the expert and your integrity and ethics are on the line here. todd On Friday, April 26, 2013 12:24pm, "SunHarvest" <e...@harvesthesun.com> said:
I have a crazy...I mean creative customer who wants a BB system so that he can run off-grid during peak and partial-peak rate hours: 1 to 7pm is peak, 7 to 9pm is partial from PG&E. He got this great idea from a tech at a reputable power optimizer manufacturer, whom I will not name here, who said, "you've got the batteries just sitting there; why not put them to work?" Initially he wanted his PV to operate while the sun is shining and the grid is down...and his batteries to supply power when the sun and grid is down. But now he wants his back-up system to do it all. We've touched on all the obvious points: - Peak buying is also peak selling - Physics and efficiency losses determine that the energy he "saves" will never equal the energy he can put back into his system. - Decreased battery life due to increased cycling - Costs for batts and special inverters versus generator What is the definitive argument against BB in general and this "peak shaving" idea in particular? Thanks pros. Eric SunHarvest ----- Original Message ----- From: [mailto:toddc...@finestplanet.com] toddc...@finestplanet.com To: [mailto:re-wrenches@lists.re-wrenches.org] RE-wrenches Sent: Friday, April 26, 2013 11:57 AM Subject: Re: [RE-wrenches] Battery Back-up and Grid Tie our power outages generally come from bad weather too... and of course when the weather is bad the pv does next to nothing. so for emergency backup, i recommend a generator. todd On Friday, April 26, 2013 10:33am, "Bill Turberville" <[mailto:billt...@ece-llc.com] billt...@ece-llc.com> said: Not very often, and usually for no more than an hour or two, although it has been down as long as 5 days, either during tornado season, or ice taking down power lines. What these people are looking for is Just In Case a big event happens. They do not want to have all those panels just sitting there. From: [mailto:re-wrenches-boun...@lists.re-wrenches.org] re-wrenches-boun...@lists.re-wrenches.org [mailto:[mailto:re-wrenches-boun...@lists.re-wrenches.org] re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Jay Peltz Sent: Friday, April 26, 2013 12:25 PM To: RE-wrenches Subject: Re: [RE-wrenches] Battery Back-up and Grid Tie Hi bill Just how often is your grid down? Jay Peltz power Sent from my iPhone On Apr 26, 2013, at 10:01 AM, Bill Turberville <[mailto:billt...@ece-llc.com] billt...@ece-llc.com> wrote: I live in a TVA area where there is a Feed In Tariff. Everything that is generated by the PV array feeds into the grid through a Generation Meter that ties-in ahead of the house meter. I have started getting calls from customers who hate having a solar array that does not generate when the grid is down but the sun is shining, but who also want to get the $.12 premium when the grid is connected. We have lots of systems with SMA Sunnyboy inverters, but more with Enphase micro-inverters. Rather than trying to reinvent the wheel, what you found to be the best solution for this type of installation? W.C. (Bill) Turberville P.E. President ECE Solar Electrical Contracting Enterprises LLC 3080 Stage Post Road Suite 107 Bartlett, TN 38133 901-348-9230 ext 101 phone 901-348-2192 fax 901-289-6346 cell [mailto:billt...@ece-llc.com] billt...@ece-llc.com NABCEP Certified PV Installation Professional 032611-320 _______________________________________________ List sponsored by Home Power magazine List Address: [mailto:RE-wrenches@lists.re-wrenches.org] RE-wrenches@lists.re-wrenches.org Change email address & settings: [http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org] 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] http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: [http://www.re-wrenches.org/etiquette.htm] www.re-wrenches.org/etiquette.htm Check out participant bios: [http://www.members.re-wrenches.org] www.members.re-wrenches.org Sent from Finest Planet WebMail. _______________________________________________ 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 Sent from Finest Planet WebMail.
_______________________________________________ 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
