[RE-wrenches] How to sell maximum amount from EG4

Fri Jun 26 15:06:34 PDT 2026

This sounds like the old buy all sell all system with two meters.  I didn't
realize any utilities were still doing this.  But the way that we'd do it
on a grid-tie system was have one meter measuring production that then
connected into the grid on the utility side of the meter going to the
house.  During a sunny day, the energy used by the house would first be
sold to the utility through the production meter, then bought right back
through the normal loads meter.

Doing a battery backup system would, I think, be wired up the same way.
The PV array would have its own grid-direct inverter selling power to the
grid, and then the battery backup system would draw power from the grid for
charging -- it would be set up as a UPS type system, not knowing that any
solar existed at all.

If the grid went down, you would not be able to power the house or charge
the batteries from the solar, as it would be connected on the dead grid
side of any transfer switches from the backup power, and I think this would
meet the utilities intent -- if the grid is down, they cannot purchase any
electricity, so therefore, generating electricity to recharge your
batteries or use would not be allowed.

Frankly, if faced with a tarriff like this, I would seriously look into
what it would take to get rid of the grid connection entirely and do an
actual off-grid system.  I figure that most batteries right now cost about
4 to 5 cents/kWh for energy stored then used.  So it would depend on the
load profile and how much was used during the daytime and how much at
night, but if the buy rate is more than 2 or 3 cents more than the sell
rate, I would think it would be cheaper to invest in batteries and pay 0
markup during the daytime, and 4 or 5 cents battery cost at nighttime,
rather than paying more than 2 or 3 cents markup all the time.

Usually, even when faced with very unattractive buy/sell rates, I still
recommend that people maintain their grid connection, even if only to use
it in place of a standby generator fill in during winter weather.  Even
paying a $50/month standby charge to maintain a grid connection you almost
never use can be cheaper than maintaining an actual physical generator.
But if you aren't allowed to even use your own solar power on site without
incurring their markup, then that could be a different story.

Zeke

On Fri, Jun 26, 2026 at 10:39?AM Christopher Warfel via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> > Our local utility has a requirement that ALL generation be sold to them
> at avoided cost, and that ALL purchases be made at tariff rate.  A couple
> of years ago before installing an EG4 system (which I did my first one
this
> past year), I told the president of the coop that I did not think that was
> possible with multi mode systems.  I've tried a lot of different settings
> in the EG4 but it seems not to make a big difference.
>
>
> Does anyone have knowledge of how to do this?  Signature Solar did not
> have a definitive answer, and what we have tried so far, has not really
> produced the results I was hoping for.
>
>
> Thank you, Chris
>
> >
> --
> Christopher Warfel, PE
> ENTECH Engineering, Inc.
> PO Box 871, Block Island, RI 02807
> (401) 447-5773

On Fri, Jun 26, 2026 at 1:13 PM <re-wrenches-request at lists.re-wrenches.org>
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> Today's Topics:
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>    1. How to sell maximum amount from EG4 (Christopher Warfel)
>    2. Re: How to sell maximum amount from EG4 (Dave Tedeyan)
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> ----------------------------------------------------------------------
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> Message: 1
> Date: Fri, 26 Jun 2026 10:36:32 -0400
> From: Christopher Warfel <cwarfel at entech-engineering.com>
> To: re-wrenches at lists.re-wrenches.org
> Subject: [RE-wrenches] How to sell maximum amount from EG4
> Message-ID:
>         <adcab7b2-1d88-4896-af75-3bc90406546d at entech-engineering.com>
> Content-Type: text/plain; charset=UTF-8; format=flowed
>
> > Our local utility has a requirement that ALL generation be sold to them
> at avoided cost, and that ALL purchases be made at tariff rate.  A couple
> of years ago before installing an EG4 system (which I did my first one this
> past year), I told the president of the coop that I did not think that was
> possible with multi mode systems.  I've tried a lot of different settings
> in the EG4 but it seems not to make a big difference.
>
>
> Does anyone have knowledge of how to do this?? Signature Solar did not
> have a definitive answer, and what we have tried so far, has not really
> produced the results I was hoping for.
>
>
> Thank you, Chris
>
> >
> --
> Christopher Warfel, PE
> ENTECH Engineering, Inc.
> PO Box 871, Block Island, RI 02807
> (401) 447-5773
>
>
>
> ------------------------------
>
> Message: 2
> Date: Fri, 26 Jun 2026 10:42:53 -0400
> From: Dave Tedeyan <dave at sungineersolar.com>
> To: cwarfel at entech-engineering.com,  RE-wrenches
>         <re-wrenches at lists.re-wrenches.org>
> Subject: Re: [RE-wrenches] How to sell maximum amount from EG4
> Message-ID:
>         <CAM3Q7f1Qsbhpi=
> hO6BXe8nkQH-WvLkHrJSSm-B_-rK_AW9FnVw at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> You can try contacting EG4 directly. I've had good luck talking to them as
> well when I have had questions. They were good about helping me derate the
> grid sell for a couple inverters to stay below our utilities residential
> limit, and then signing a form for us to give to the utility.
>
> Cheers,
> Dave
>
> On Fri, Jun 26, 2026 at 10:39?AM Christopher Warfel via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
> > > Our local utility has a requirement that ALL generation be sold to them
> > at avoided cost, and that ALL purchases be made at tariff rate.  A couple
> > of years ago before installing an EG4 system (which I did my first one
> this
> > past year), I told the president of the coop that I did not think that
> was
> > possible with multi mode systems.  I've tried a lot of different settings
> > in the EG4 but it seems not to make a big difference.
> >
> >
> > Does anyone have knowledge of how to do this?  Signature Solar did not
> > have a definitive answer, and what we have tried so far, has not really
> > produced the results I was hoping for.
> >
> >
> > Thank you, Chris
> >
> > >
> > --
> > Christopher Warfel, PE
> > ENTECH Engineering, Inc.
> > PO Box 871, Block Island, RI 02807
> > (401) 447-5773
> >
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> End of RE-wrenches Digest, Vol 19, Issue 173
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-- 
Zeke Yewdall
PV Engineer
NABCEP #031508-89
zeke at darkforestsolar.com
303-523-3592
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