Back in the old days, when utilities routinely were a huge pain to work
with, we just created a backup loads sub panel, and ran those circuits
off grid, and used the grid in place of a generator. No way to back
feed, and the customer got the benefits of a reduced bill and backup
power. It was not as efficient though, especially with lead acid
batteries.
In Hawaii, many of the utility circuits are maxed out for solar
penetration, and so its literally impossible to do a regular GT system
on many parts of the islands anymore. Those customers have to do setups
like I described. The trick to improving the efficiency, is having some
dump loads to take the surplus PV power after the batteries are full,
either water pumping to a cistern, extra heating or extra cooling, and
have some thermal mass in the house to hold those extra BTUs (+ or -).
Here on the mainland, we're going to be doing stuff like that in the
future.
Ray Walters
Remote Solar
On 1/12/2026 3:32 PM, Zeke Yewdall via RE-wrenches wrote:
Did the utility say that it was feeding back in 1A continuous, or had
fed back in 1A at some point?
With better metering, especially the new smartmeters, utilities are
finding a lot of PV systems that are connected without authorization,
by seeing tiny amounts of backfed power that used to be invisible. I
had one SolArk system get caught. For the systems that operate in
parallel with the utility doing zero sell it needs to have a certain
offset for the minimum amount drawn from the utility, such that it
doesn't inadvertently sell a little bit during readjustment during
load changes. In the case of the SolArk system, it was set to 0 watts
from the utility, and when the load changed, it would sell a little
bit for a few seconds. This is enough for the utilities to see with
the new meters, and lets them know that there is solar that they
haven't been told about. I changed it to a 120 watt minimum draw from
the utility, and it no longer overshoots zero during load changes now,
but also draws power from the utility all of the time. We do have to
get this system permitted and an interconnection agreement in place
soon though, because now they know about it, and they are going to
pull the customers service if he does not do that, or get rid of the
solar completely. This is something that everyone should know, that
operating in parallel with the grid without having an interconnection
agreement is a risk.
The only way to safely do solar without getting an interconnection
agreement (and I think the only legal way) is to never have the solar
operating in parallel with the grid, but have a transfer switch such
that the solar is never connected to the utility. For many of the
newer systems, connecting the grid to the generator input port instead
of the grid port can accomplish this (though it varies from system to
system -- some systems can operate in parallel with the generator
too). But almost all of the new systems (all in ones, some operating
modes of the Radian and XW) operate in parallel with the utility
rather than switching back and forth, so when the grid is connected to
the grid input of the inverter, it can potentially backfeed the grid,
even if for only a second or less.
The HBX/LBX modes of the SW and the Outback switch back and forth,
rather than operating in parallel, and so should not have this issue.
I think... I am not 100% certain even with these modes, although I've
never seen them have an inadvertent sell issue, due to the inverter
being off anytime it's connected to the grid. The transfer switch
in this case would be inside of the inverter.
Zeke
_______________________________________________
List sponsored by Redwood Alliance
Pay optional member dues here: http://re-wrenches.org
List Address: [email protected]
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/[email protected]/
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
_______________________________________________
List sponsored by Redwood Alliance
Pay optional member dues here: http://re-wrenches.org
List Address: [email protected]
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/[email protected]/
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
