[RE-wrenches] Solaredge AC-coupling

[John Berdner]

Kirk:

We have a new version of firmware (in production January 1, 2013) that supports frequency shift power control, e.g. Sunny Island.
I am preparing a white paper on how to set it up but can walk you through it or we can preprogram it for you here and drop ship it to you for your distributor.
All of our recent product has an SD card slot so you can upgrade firmware in the field to the latest version should you receive an inverter with older firmware.
Feel free to contact me offline to discuss details on how to program.

We do not support ac coupling to other battery inverters that do not use a frequency shift algorithm.
There are a couple of issues with AC coupling to inverters that just use a relay to disconnect the grid tied inverter with a relay (ours our anyone else's).


1)      Every time you open the relay you create a grid fault and the isolation relays in the grid tied inverter cycle. Cycling on an off every 5 minutes is really hard on the relays and can lead to premature failure.

2)      The result of this relay cycling is that you end up with on/off charge control which is not very effective.  On/Off charge means the battery can never become fully charged (negative offset from the target set point).  If you increase the set point then you increase gassing which results in higher maintenance for flooded batteries and possible damage for sealed batteries.  It is a no win situation.

The magnitude or these downsides also depends on the intended application.  For a true off grid application I would never recommend AC coupling unless a frequency shift algorithm is used.  An off grid system has the potential to spends a lot of time in "regulation" and, because of the on/off charge control, the batteries never really get charged - which is not good for performance or longevity.  In a grid backup application these downsides are less of an issue because the grid is rarely down and when it is down the battery is normally discharging so the system is unlikely to spend much time in "regulation".  In my experience folks that have grid backup systems do not have the same energy awareness as those that live off grid and so they use more power.

Best Regards,

John Berdner
General Manager, North America

[cid:image001.jpg at 01CDDDC4.BBCAA1C0]

3347 Gateway Boulevard, Fremont CA 94538 USA  (*Please note of our new address.)
T: 510.498.3201 ext 747
M: 530.277.4894

From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Kirk Herander
Sent: Tuesday, December 18, 2012 1:16 PM
To: RE-wrenches
Subject: [RE-wrenches] Solaredge AC-coupling

Hello,

Anyone out successfully AC-coupled a Solaredge inverter with an Outback or other battery-based inverter? Thanks. I may want to do it for an upcoming job.

Kirk Herander
VT Solar, LLC
dba Vermont Solar Engineering
NABCEPTM Certified Inaugural Certificant
NYSERDA-eligible Installer
VT RE Incentive Program Partner
802.863.1202

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