[RE-wrenches] Grid tie with BB

[Phil Undercuffler]

On Sunday, September 2, 2012, Richard L Ratico wrote:

> If the clients have a Trimetric or similar meter, perhaps they could be
> trained
> to power some loads with their inverter, while simultaneously charging
> their
> batteries and minding the charge rate, rather than tweaking the CC setup.
> Make
> hay while the sun shines so to speak, particularly when the battery is
> small
> relative to the array.
>
> Dick
>
> --- You wrote:
> Thanks Dan/Dick and Larry $E2Ai
>
> My concern was too high a charge rate, particularly when the batteries are
> cycled during or after an outage when the controllers are delivering
> maximum
> current and the inverter is not selling, yet not wanting to limit the
> charge
> controllers when we$E2Aore back in grid tied mode. Outback noted that you
> can
> just limit the controllers during extended outages, but I would prefer that
> customers not have to make adjustments to the charge rates.
>
> What I failed to consider is the particularly high charge rates that AGMs
> are
> able to withstand compared to FLAs. With a few tweaks to the system design
> we
> can easily hit a ~ .25C rate which is ideal for the batteries.
>
> I like the perspective of the inverter as diversion controller when
> it$E2Aos in
> sell mode.
>
> Thanks again for your help!
>
> Rich
>
>
>
> From: re-wrenches-bounces at lists.re-wrenches.org <javascript:;>
> [mailto:re-wrenches-bounces at lists.re-wrenches.org <javascript:;>] On
> Behalf Of
> dan at foxfire-energy.com <javascript:;>
> Sent: Sunday, September 02, 2012 11:01 AM
> To: RE-wrenches
> Subject: Re: [RE-wrenches] Grid tie with BB
>
>
>
> I'm with Dick. I liken grid tied inverters to diversion controllers. MPPT
> charge
> controllers (In Grid Tie Mode / talking to a HUB), pretty much just track
> a max
> power from the array. Good luck.
>
>
>
> db
>
>
>
>
> Dan Brown
> Foxfire Energy Corp.
> Renewable Energy Systems
> (802)-483-2564
> www.Foxfire-Energy.com
> NABCEP #092907-44
>
>
>
> -------- Original Message --------
> Subject: Re: [RE-wrenches] Grid tie with BB
> From: Richard.L.Ratico at VALLEY.NET <javascript:;> (Richard L Ratico)
> Date: Sun, September 02, 2012 9:16 am
> To: re-wrenches at lists.re-wrenches.org <javascript:;>
>
> Rich,
>
> If I understand your question, I think you're missing the functioning of
> the
> inverter. Working independently of the charge controller, it will sell to
> prevent overcharging the batteries. Correctly configuring the inverter's
> voltage
> thresholds accomplishes this.
>
> Dick Ratico
>
>
> --- You wrote:
> Wrenches,
>
> I'm have a mental block with battery backup systems such as the Outback
> Radian. Perhaps someone can help me get over it!
>
> Essentially these systems sell back power off the top of the battery bank
> and the array is maintaining the state of charge of the battery bank
> through
> traditional charge controllers. If you have a modest battery bank sized for
> limited use on critical circuits and a good size array for the benefit of
> net metering I would think it would be necessary to limit the current the
> charge controllers are capable of delivering to the battery bank to prevent
> damage to the batteries when the controllers are Bulking or Absorbing, but
> then it would seem that we limiting the utility of the larger array. If the
> current from the controllers was not limited they will self-limit as
> voltage
> rises, plus I suppose they will mostly be in float mode except when the
> batteries are cycled but again it seems that we are limiting the capability
> of the array compared to a straight grid tied system with a traditional
> grid
> tied only inverter.
>
> An example would be a 8000 watt array using a couple of flexmax80
> controllers with a string of 8 - L16 AGMs feeding a Radian.
>
> What am I missing here?
>
> Thanks
>
> Rich
> --- end of quote ---
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