Deye/Sunsync inverter - battery full, still drawing from grid

[kolek]

Connected the 2 CT on the grid line L1 and L2, oriented correctly.
Problem is not solved.
This is what's happening with grid off:
- house load is 1.42kw, supplied by battery, everything looks normal.


Then I turn on grid, and it stops making sense.
- battery usage falls from 1.52kw to 0.05kw
- the house load disappears and goes to 0
- for grid, the power LED is actually flowing TOWARD the grid, like it's feeding power back to the grid, even though that shouldn't be possible with my settings.

So apparently I have solved the world's energy problems. At the flip of a switch, I'm able to create a house that uses no power, doesn't require a battery, and can send power generated from nowhere back to the grid. Makes no sense.

Can anyone help? Totally lost on this.

 

[XO4001]

Reverse the wires from the CT's.

 

[kolek]

Reverse the wires from the CT's.

You mean reverse the CT direction, right? I installed them with arrow pointing toward the inverter which is what the manual says to do but I will reverse their direction on the wires.

I reversed both the CT, turned on the grid, and the inverter went from pulling 30A out of my battery to suddenly pulling 90A out of my battery, even though I'm not using anywhere near 90A. The CT now both have their arrows pointing away from the inverter, previously they were pointing toward the inverter per the manual.

 

[XO4001]

You mean reverse the CT direction, right? I installed them with arrow pointing toward the inverter which is what the manual says to do but I will reverse their direction on the wires.

Yes change the black for white wire Or change the direction of the CT's

 

[kolek]

Nevermind I see the polarity of the wires in the manual, missed that the first time around, fixing everything to be correct.

 

[kolek]

FIXED! Wow, finally. Thank you so much.
By fixed I mean, it's allowing the house to run off the battery after I turn on the grid.

I'm assuming TOU will also work now, hoping it will anyway.

 

[1201]

glad to hear. so it was just a matter of installing the CTs and in the right direction?

FIXED! Wow, finally. Thank you so much.
By fixed I mean, it's allowing the house to run off the battery after I turn on the grid.

I'm assuming TOU will also work now, hoping it will anyway.

 

[kolek]

glad to hear. so it was just a matter of installing the CTs and in the right direction?

Yes, was so focused on the settings that I never considered that it could be an external issue like the CTs.
Thank you for helping.

I guess the point of all this is setting up the CT is not "optional"

 

[kolek]

One thing that kinda blows my mind is just by reversing one of the CT and turning on grid, the system started pulling 90A out of my battery (as measured by my JK-BMS) and I have no idea where that power went. Only possible explanation I can think of is it was sending that power into the grid because my house load was static at 30A. If anyone has an explanation for what could have happened I would like to hear it.

 

[1201]

One thing that kinda blows my mind is just by reversing one of the CT and turning on grid, the system started pulling 90A out of my battery (as measured by my JK-BMS) and I have no idea where that power was going. Only possible explanation I can think of is it was sending that power into the grid because my house load was static at 30A. If anyone has an explanation for what could have happened I would like to hear it.

Probably what happened. Do you have a graph of that time frame?

 

[kolek]

Probably what happened. Do you have a graph of that time frame?

Unfortunately I don't have anything storing data on the system yet. No Solar Assistant, etc. And I'm not using Deye's online system.

 

[kolek]

Actually, I don't see why TOU settings are necessary for this use case, here's why:

On the battery screen, you set the battery shutdown voltage (or percentage) to, say, 10%

Then if the battery goes below 10%, inverter switches to grid and doesn't charge the battery, right?

Then when solar pushes the battery above the "restart" voltage, inverter switches back to running from battery.

That's all I need. Why do I need to mess with TOU?

 

[Hedges]

TOU is only if rates change depending on the time you use power.

 

[kolek]

TOU is only if rates change depending on the time you use power.

So you agree I should have no trouble having it achieve my objective without TOU?

 

[Hedges]

Your utility may offer or force on you a time of use rate.
Your inverter probably has functions to shave imports and exports at different times.

You may or may not decide you can save money with time of use rates. I decided I did when rates were higher while there was sunlight on my panels, because I backfed for credit. "times" have changed and it is no longer beneficial for me, but is now required for all PV net metering customers.

What were your objectives, again?

 

[kolek]

What were your objectives, again?

Very simple. Never use grid unless battery is dead. Never charge battery from grid, only from solar.

 

[Hedges]

OK, it is to maximize use of solar.
TOU has nothing to do with meeting that objective.

I would think another objective would be to not have the power go out.
Therefore, you want enough charge in the evening to last until morning.
So when there is less sunshine, use less power to ensure sufficient charge during the day.

That could mean doing without some loads you could have powered during the day, in order to not rely on grid at night.
You could run off PV and battery until battery is dead, then switch to grid. But if grid fails, you are out of power.
So you might want to predict if battery won't last until morning and charge battery from grid, or maybe transfer loads direct to grid and just have PV charge battery.

 

[kolek]

You could run off PV and battery until battery is dead, then switch to grid. But if grid fails, you are out of power.

I understand that's a concern for some people, but here grid practically never fails, so having failover to battery backup is not a goal at the moment. My electric bill, on the other hand, never fails to arrive and the price of electricity here is bonkers, so reducing grid consumption is my only focus at the moment.

 

[Hedges]

No net metering, so PV --> battery --> loads is the only way?
With seasons and weather, PV will sometimes come up short.
Maybe you'll be able to expand PV for bad days.
More battery can also let you last another day, but is many times the price of PV panels. At least over here.

Just saw a US source (GStar sold by liquidator InXeption) for $0.14/W (shipping not included.)
What are your best prices on PV?

With high utility rates and low PV panel prices, you could install 5x or 10x the PV you need on good days.
Well, where the point of no additional savings comes depends on how many lightly overcast days.
Some days I get 10% of peak power, other days 2%.

After a year of logging daily production you can do the financial analysis and make a more reasoned decision.
(I've got piles of panels at home, at my other home, sister's home, neighbors home. Easier to plan and buy than to execute. Planning to install before net metering reservations expire.)

 

[kolek]

No net metering, so PV --> battery --> loads is the only way?

Right, if I did net metering I would have had to comply with regulations and get permits and have an approved electrician do the wiring and I am not aware of any Japanese government-approved inverter here that does "off-grid," plus they keep cutting the price they buy back power for so eventually I expect the price to go to practically zero. Just not worth it in my opinion to sell power back to the power company, but that's what 99% of solar installs here in Japan do.

With seasons and weather, PV will sometimes come up short.
Maybe you'll be able to expand PV for bad days.

Right, unfortunately Deye inverters apparently aren't a good choice for overpaneling but I still don't know enough about that option and the actual limitations of my inverter.

With high utility rates and low PV panel prices, you could install 5x or 10x the PV you need on good days.

I've been thinking a lot about how to be do that. Is there a way other than overpaneling to do that? Previously you mentioned putting parallel strings at different angles, I assume that's my only option, aside from buying more SCC to go with the additional panels? Do you have a recommended charge controller that is cheap and overpaneling friendly?