David,
I have pdf copies of the Trace SW manuals, rev. 4.01 (the most widely
used) and rev. 1.0 (the first from around 1993, seldom still in
operation). If you need either one contact me off list.
For a short period of time around 2002 there was a rev. 4.10 version of
the SW that used a separate component called a Grid Tie Interface (GTI).
The GTI was added to specifically address, as I recall, the possibility
of grid backfeed when the AC input (from a generator, I think, but this
may be incorrect) matched the AC output to the loads. It was an awkward
and short-lived solution that was succeeded by the (also short-lived)
SW+ series, before the XW series replaced it. I needed to include two of
these in a GTBB (early Grid-Tie with Battery Backup) dual-inverter
system that I installed for Jane Fonda at her New Mexico ranch. As Jerry
says, fun times (way more fun than today, I suspect).
Your simplest real-world solution, which the utility may or may not
accept, is to run grid power into AC2, the generator input hot terminal.
Then the inverter functions only as an input source. If the utility
determined the 1A backfeed on the basis of its own test, a retest may be
sufficient to ascertain that there's no longer the possibility of backfeed.
Allan
On 2026-01-12 11:28 am, Dave Angelini Offgrid Solar wrote:
Sounds like this could happen. The (really) old SW input had an
option to do this. Disconnect this. Do you have the manual? I might
but not nearby now. Good Luck
On 2026-01-10 1:12 pm, David Palumbo via RE-wrenches wrote:
Wrench,
An off-grid installation of mine from many years ago has is now
using grid power instead of a generator. The utility is telling
the homeowner that they are going to disconnect him because his
house is back feeding 1 amp into their grid power.
I've been retired for many years now and did not do any of the
work to connect the utility power to his Trace SW4024
inverter/charger. The utility power became available when his son
brought in utility power for his maple sugaring operation in the
neighborhood, and the father connected power to his house to
replace his fossil fueled generator for additional charging into
his battery bank. They do not have a grid interconnect sellback
agreement with the utility.
I have no experience with this, but I'm assuming that the utility
grid is seeing power from its input connection to his Trace
SW4024. Does that sound right? If so, is there a simple solution
to fix this problem while continuing to use the grid power
through his SW inverter?
Thanks for any advice that may help.
David Palumbo
Hyde Park, VT
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