[RE-wrenches] PV Production Meter on a XW System

[Gary Willett]

Aaron:

Manually-read legacy utility meters, in many cases, are set up to 
accumulate current flow in either direction as kWh consumed. This was 
done because dishonest people would turn the meter upside down for part 
of the month, and then put it back normal before the meter-reader showed up.

My electric service has a bi-directional "smart" utility meter that 
presents a cyclic display of kWh delivered (code 20) and received (code 57).

For my GTBB system, I use a GE KV2c bi-directional meter between the XW 
AC1 conductors and the grid interactive back-fed PV breaker. This 
provides a separate register for the kWh "bought" and the kWh "sold" 
from the XW's perspective.

The XW inverter AC output feeds a protected loads panel, which in my 
case contains everything except the electric oven and the electric 
dryer. My 3-ton AC unit runs off the XW inverter under grid-up, but is 
switched off via a contactor when in grid-down. I have an autostart 6kW 
Generac EcoGen connected to the XW AC2 for back-up in event of an 
extended grid outage.

The KV2c "bought" register accumulates the kWh consumed when the XW is 
in AC Pass-Thru mode or grid supplement mode (PV kW not adequate to 
deliver load demand). The KV2c "sold" register accumulates the kWh 
delivered by the XW to the main service panel. Some of these kWs power 
my 240V loads if they are active.

Regards, Gary Willett, PE


On 8/24/2012 10:44 AM, Kent Osterberg wrote:
> Aaron,
>
> Is the objective to measure all of the energy produced or only that 
> which is delivered to the grid? To measure the energy sold to the 
> grid, the meter goes between the XW and the grid, but it must be an 
> electronically detented meter that only records energy flow in one 
> direction.
> Kent Osterberg
> Blue Mountain Solar, Inc.
> www.bluemountainsolar.com
> t: 541-568-4882
> On 8/24/2012 7:29 AM, Aaron Mandelkorn wrote:
>> Wrenches,
>>
>> I would like to here some thoughts on monitoring the production a XW 
>> in grid tie with battery backup mode. I normally use the Sunny Island 
>> for my grid tie with battery backup systems and am considering going 
>> with the XW on my next one.  Just wondering where in the system one 
>> would wire the AC PV Production meter to best represent the amount of 
>> power sold to the grid.  We have performance based incentives around 
>> here that require metering of the power going back to the grid.  With 
>> the SI systems this is easily accomplished by putting the required 
>> meter after the sunny boy before going to the critical loads panel. 
>>  Any ideas about how to accomplish this with the DC coupled XW 
>> system? Your thoughts would be greatly appreciated.
>>
>> Aaron Mandelkorn
>> NABCEP Certified PV Installer
>> Owner / Operator
>>
>> Renewable Energy Outfitters
>> Box 65 Salida, CO. 81201
>> (970)596-3744
>> reosolar at gmail.com <mailto:reosolar at gmail.com>
>> www.reosolar.com <http://www.reosolar.com>
>>
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