[RE-wrenches] BACKUP system revival

[William Miller]

Dana:

I have never incorporated a transfer switch with a battery inverter. The
inverter’s internal transfer relay with the smarts it provides has always
been preferred.

I have of course used a transfer switch for generator-only systems. In some
cases the generator is rated smaller than the utility feed and the user
needs to live within the capabilities of the generator on the rare occasion
when the utility is down.

So your scenario brings up an interesting option: using a full 200 amp
transfer switch means the Radian is not a 50 amp bottleneck when the
utility is up. The Radian would become an ersatz generator connected to the
gen input on the transfer switch.

The wrinkle is: how do you provide an AC input to the Radian to charge
batteries when the grid is up without triggering the transfer switch?

When the Radian sees AC input it wants to through-transfer. There must be
some way to configure the transfer switch to not trigger when the grid is
up. Then a breaker from the main panel feeds the Radian, the Radian charges
batteries and the Radian output goes nowhere.

However when the grid does go down and the transfer happens you have a
power flow loop which will shut down the Radian.

I imagine there is some scheme of running the Radian input through a
contractor that would be opened when the transfer switch connects the
Radian output to the load. I think if you solve that you may have a working
option. This does add a layer of complexity, however.

Good luck.

William Miller

PS:  You could use an outboard battery charger, however that is a waste of
the very good battery charger built into the Radian

Wm

On Sat, Dec 17, 2022 at 8:28 AM Dana Orzel via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> Hey All a Cheery Season to you all!
>
>
>
> I inherited a backup system that had “failed”. It was unwired, & poorly
> labeled.
>
>
>
> 1200 AHR AGM Battery – 1 Radian 8KW inverter – 200 amp Generac transfer
> switch – No solar - Feeding a 200 amp house panel.
>
>
>
> First I explained the there were too many loads for an 8KW inverter. It
> could & may overload the 8KW inverter. They said “it had worked fine for 5
> years & they were OK with it as is please get it back up”…
>
> Replaced the existing Eaton transfer switch as the Generac controller was
> shot, with a Generac 200 amp Xfer switch complete with controller &
> transfer switch.
>
> Rewired & had to recharge the 48 volt battery from 20volt back up to full
> with a pair of IOTA chargers in series.
>
>
>
> The original trigger was 3 wires from the Radian to the 12 volt & AUX
> output to the input on the Generac controller. These were disconnected on
> the Generac end. So no clue or labeling there.
>
>
>
> I called Outback & they called it Redneck engineering & send me a few
> articles to read.
>
>
>
> Has anyone configured a backup in this manner?
>
>
>
> All suggestions appreciated, thanks & wishing you all a safe & sane season!
>
>
>
>
>
>
>
> Dana Orzel                              Great Solar Works, Inc.
>
> *C - 208.721.7003                       dana at solarwork.com
> <dana at solarwork.com>*
>
> Idaho Contractor - # 028765         Idaho PV # 028374
>
> www.greatsolarworks.com            www.solarwor.com
>
> *"Responsible Technologies for Responsible People since 1988"  *
>
>
>
> *P* Please consider the environment before printing this email.
>
>
>
>
> _______________________________________________
> List sponsored by Redwood Alliance
>
> Pay optional member dues here: http://re-wrenches.org
>
> List Address: RE-wrenches at lists.re-wrenches.org
>
> Change listserver email address & settings:
> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>
> There are two list archives for searching. When one doesn't work, try the
> other:
> https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/
> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org
>
> List rules & etiquette:
> http://www.re-wrenches.org/etiquette.htm
>
> Check out or update participant bios:
> http://www.members.re-wrenches.org
>
> --

William Miller
Miller Solar.com
895-438-5600
www.millersolar.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20221217/400a05e8/attachment.htm>