[RE-wrenches] Metering a whole house Outback system

[David Katz]

Hilton,
I am metering an Outback Radian in this situation.  I am using an Elkor meter with a pair of current transformers, but you can use and meter with CTs.  Just feed the two AC lines from the main panel through the CTs to the AC in of the inverters, then run the wires coming from the inverters output, going to the sub-panel back through the same CTs, keeping the L1 and L2 in phase.  This way the utility power cancels and you only read the inverters output.  You get the sum of what goes to the grid and what is used kb the subpanel.  It also subtracts what is used to float the batteries.
I read my Elkor meter with a SolarLog monitor.
David Katz

Sent from my HTC smartphone on the Now Network from Sprint!


----- Reply message -----
From: "Hilton Dier III" <hiltondier at gmail.com>
To: "re-wrenches at lists.re-wrenches.org" <re-wrenches at lists.re-wrenches.org>
Subject: [RE-wrenches] Metering a whole house Outback system
Date: Mon, Aug 20, 2012 9:15 am



Hello Wrenches,

Here's a metering conundrum for you.

I have a client with a dual stacked Outback 3648 inverter panel and a PV array. He has been off-grid for years, but he is now going on-grid. He is getting the Outbacks rebuilt at the factory to be grid tie compatible.

As per our local requirements, he needs a meter to read just the output of the inverter. The problem is that he has the whole house on the inverters, not just a vital loads panel. He wants to keep it that way. That gives him two separate outputs, "AC Out" to the main breaker panel and "AC In(teractive)" to the grid connection. If he just puts a meter on the AC In line, he will lose track of the inverter output that goes to power the house, and he'll get his output reduced by any grid-based charging he does.

There is a "green tag" method of wiring the meter to avoid this, but it is designed for two single-leg 120VAC outputs and the stacked Outbacks are putting out 240VAC on two legs.

Aside from dropping $600 on an e-Gauge, is there any way to get around this?

Many thanks,

Hilton

--
Hilton Dier III
Renewable Energy Design
Partner, Solar Gain LLC
453 East Hill Rd.
Middlesex, VT 05602

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