[RE-wrenches] PV harvest in grid-tied systems

David Katz dkatz at aeesolar.com
Wed Apr 18 09:13:56 PDT 2012


William 
I am using an Elkor meter with RS485 output connected to a SolarLog1000. There are two current transformers connected to the Elkor meter. I ran each wire from the 240 vac from the main load center through a current transformer to the Radian ac input. Then I ran the Ac output line from the radian back through the same current transformers to the subpanel for backed up loads. That way the ac passing through the radian from the grid to the subpanel reads 0 since it passes both way through the CTs, but power coming from the Radian is measured going to the grid and to the loads in the subpanel.
I am traveling in Europe at the moment and I done have a computer so I do not have the link to the monitoring. I will try to get it so you can take a look.
David

Sent from my iPhone

On Apr 18, 2012, at 2:30 PM, "Bill Loesch" <solar1online at charter.net> wrote:

> 
> David,
> 
> What did you choose for revenue-grade monitoring?
> 
> Comments?
> 
> Bill Loesch
> Solar 1 - Saint Louis Solar
> 314 631 1094
> 
> 
> On 18-Apr-12 4:01 AM, David Katz wrote:
>> William
>> I have a grid tie system with a Outback Radian and Xantrex 600 volt charge controller with 4kw of modules and it sells back flawlessly.  I have revenue-grade monitoring on the system and I am very happy with the output.
>> David Katz
>> 
>> Sent from my iPhone
>> 
>> On Apr 16, 2012, at 6:51 AM, "William Miller"<william at millersolar.com>  wrote:
>> 
>>> Friends:
>>> 
>>> There has been recent discussion on this forum about PV production in
>>> grid-tied with battery systems.  I have been faced with this same problem
>>> in a 3 XW system installed in 2009.
>>> 
>>> The customer's power bill never went down.  PV harvest was abysmal.  The
>>> system would create great short circuit current but would not harvest into
>>> the batteries.
>>> 
>>> It is starting to appear the XW firmware was at fault.  The inverters would
>>> charge the batteries too high so the charge controllers would back
>>> off.  Upgraded firmware seems to be helping, but the data set is still limited.
>>> 
>>> Remember this:  just because a PV system can produce does not mean it
>>> will.  The charge controller knows only one thing:  battery voltage.  If it
>>> is high, production is curtailed.
>>> 
>>> Off-grid production will also be reduced is consumption is curtailed.
>>> 
>>> Charge controllers that can be set for grid-tied applications help, but
>>> only if the inverter(s) do not keep the battery voltage too high.
>>> 
>>> William Miller
>>> 
>>> 
>>> Miller Solar
>>> Voice :805-438-5600
>>> email: william at millersolar.com
>>> http://millersolar.com
>>> License No. C-10-773985
>>> 
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