[RE-wrenches] Battery Back-up and Grid Tie

[SunHarvest]

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: toddcory at finestplanet.com 
  To: 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" <billturb at 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: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at 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 <billturb at 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

    billturb at ece-llc.com



    NABCEP Certified PV Installation Professional 032611-320





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