Sunny Island Retrofit [RE-wrenches]

[August Goers]

Wrenches -

I'm looking for help in figuring out a dilemma for a Sunny Island
grid-connected system with battery backup. 

We are upgrading an old Trace grid-connected battery backup system to a new
Sunny Island based system. We just fired up the Sunny Island 5048U yesderday
along with a SB 7000US and and SB 4000US (attached to a 9 kW PV array).
Everything went well and I'm pleased with the general operation; the new
Sunny Island has a very intuitive interface. We're using an IOTA transfer
switch to allow the Sunny Boys to bypass the Sunny Island and Outback X240
autoformer to reduce losses.

The problem is that the client has a huge quantity of critical loads. I
didn't realize this at first. Most of them are 120 Volt but a few are 240
Volt. There are four critical loads sub panels and it seems like 80% of the
day to day loads are connected though these critical panels. Another
contractor installed these years ago so we didn't have any control over this
portion of the design. It's a bit crazy. The sunny island operates such that
all of the critical loads run through the Sunny Island and Outback
autoformer. If the Sunny Island and/or autoformer fail then the critical
panels will also shut down. I'm considering recommending adding a second
Sunny Island which will eliminate the autoformer and add an additional 5000
Watts of critical load ability. Secondly, I'd like to add a transfer switch
to bypass the Sunny Islands incase they fail.

We've warned the customer that their critical loads can never exceed 5000
Watts and that during a power outage they will drastically need to reduce
their usage. A point that came up, however, is that they probably won't even
know if the power does go down. The Sunny Island switches over to battery
backup completely seamlessly. 

My questions:

1. Does anyone have experience and or recommendations about a better way to
setup this system?

2. Does anyone have experience with the reliability of the above mentioned
products?

3. Does anyone have suggestions for notifying the customer if/when the power
goes down so that they can start conserving?

Any other comments are welcome. 

Thanks, August

August Goers
VP, Engineering
NABCEP Certified PV Installer R

Luminalt Energy Corporation
Office:  (415) 564-7652
Mobile: (415) 559-1525
www.luminalt.com
august at luminalt.com


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