Can Growatt Inverter do this?

RememberTheMagic

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I am looking to use a Growatt inverter to power a house. I have a large 48v 30kw battery bank to run the inverter when the sun is not shining on the panels.

So what happens when the battery is charged, the sun is shining on the panels, and the is no load requirement (i.e., nothing is turned on in the house)? How does it shed excess power?

I am looking to reduce my utility power using solar panels with Growatt inverter/charger but do NOT want to sell back to the grid.

Is there a way to tell the Growatt to use the Solar First, Batteries Second, and then utility? Likewise, whenever the inverter has excess power available and there is no load requirement, do NOT sell it back to the grid.
 
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FilterGuy

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How does it shed excess power?
When the batteries are full, the SCC shuts down all current from the panels. The amount of power being produced at that point can be calculated as 0Amps x Voc = 0Watts. So, the system does not shed excess power because excess power is not created in the first place.
 

RememberTheMagic

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When the batteries are full, the SCC shuts down all current from the panels. The amount of power being produced at that point can be calculated as 0Amps x Voc = 0Watts. So, the system does not shed excess power because excess power is not created in the first place.
Perfect. So in theory, if load requirements are low, the battery gets charged (if needed), then SCC shuts down panels to prevent putting power back to the grid?

So essentially you are grid-tied in that the utility grid is connected to the SCC to provide charging of the batteries (if you elect that to happen as an option/setting) and/or power the loads (when dark and batteries depleted)?

So its Utility - Load Panel - SCC where the SCC is protected by a 50amp breaker (in the case of a 3Kw SCC). Does this then mean the SCC is back feeding thru this 50amp breaker as well to provide power to the loads?
 

fafrd

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Perfect. So in theory, if load requirements are low, the battery gets charged (if needed), then SCC shuts down panels to prevent putting power back to the grid?

So essentially you are grid-tied in that the utility grid is connected to the SCC to provide charging of the batteries (if you elect that to happen as an option/setting) and/or power the loads (when dark and batteries depleted)?

So its Utility - Load Panel - SCC where the SCC is protected by a 50amp breaker (in the case of a 3Kw SCC). Does this then mean the SCC is back feeding thru this 50amp breaker as well to provide power to the loads?
I’m not sure what all the options your hybrid inverter will support, but your original question was what happens with ‘excess’ PV energy if it is not needed to power loads or charge a battery.

Anytime the available PV power exceeds what the SCC/hybrid inverter can make use of, it scales back the current being output by the PV array (all the way to zero, if needed).

If PV current is reduced to 0A, that means string voltage will essentially increase all the way to Voc and all potential PV energy/production is being ‘wasted’.
 
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FilterGuy

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So its Utility - Load Panel - SCC where the SCC is protected by a 50amp breaker (in the case of a 3Kw SCC). Does this then mean the SCC is back feeding thru this 50amp breaker as well to provide power to the loads?
HMMMM I wonder if my using acronyms has confused things.

A basic system looks like this.

1632781985964.png
Notice that with all-in-one units, the inverter and Solar Charge Controller (SCC) are in one box.

If there is no load and the battery is full, the the voltage at the output of the controller will go up and the the SCC will decide there is no more energy needed for the system. At that point the SCC will throttle back the current flowing through the PV array to zero. With no current flowing, there is a potential (Voltage) from the panels, but with no current, no energy is getting generated.
 

FilterGuy

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For a grid tied system it would look something like this:

1632782995578.png

In this arrangement the inverter will keep taking whatever power the SCC gives it and pump it into the breaker box. From there the energy will go to the Loads, and if there is any excess it will backfeed the grid.

For a hybrid system (no back feed) it will typically look like this:
1632783647375.png

In this arrangement, the inverter will take power from the grid to power the critical loads or charge the battery, but it will never pump power back onto the grid. There are many different configurations with where the inverter decides to get power to drive the critical load (Battery or grid). However, no matter what the configuration is, if the SCC decides the system does not need power, it shuts off the current through the solar panel and no power is generated.
 

Texas-Mark

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I thought the Growatt (or maybe it was some other brand) had current sensors that went on the mains to monitor the grid input and would tell the grid-tie inverter to cut back if it was getting ready to back-feed. I though that is what the OPer was asking about.
 

FilterGuy

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I thought the Growatt (or maybe it was some other brand) had current sensors that went on the mains to monitor the grid input and would tell the grid-tie inverter to cut back if it was getting ready to back-feed. I though that is what the OPer was asking about.

Yes, some systems that are grid-tie capable have sensors that will prevent back-feed..... but I have not studied them closely. My guess is that if the grid shuts down they will also shut down. (I can imagine how they could continue to pump out power safely if the grid is down.)
 

fafrd

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Yes, some systems that are grid-tie capable have sensors that will prevent back-feed..... but I have not studied them closely. My guess is that if the grid shuts down they will also shut down. (I can imagine how they could continue to pump out power safely if the grid is down.)
GTILs shut down when the grid goes down and the grid signal is not present.

They prevent export when the grid is present by monitoring consumption on the primary grid feed-in and generating Kurt enough power to offset all but the last 5-10 watts of that (so grid consumption drops to 5-10 watts as long there is sufficient power available through battery and/or PV array and total power required is within the max capability of the GTIL inverter.

In response to the OP’s OQ (and as I already stated in my earlier response), whenever a SCC cannot make full use of available PV power, PV power output (current) will be choked-back to match demand (including choking all the way back to 0W / 0A if needed).
 

fafrd

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Any grid-tie inverter "must" shut down when the grid goes down.
Correct. And when that happens, PV power / current is choked back to zero (unless some PV power can still be used to charge a battery and there is a SCC present and enabled to do so (whether integrated into an all-in-one or standalone).
 

fafrd

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I almost said that but since I have not played with or studied inverters with the no-backfeed sensors, I hedged my statement just in case there was something I was missing.
They are powered like a toaster oven but push out rather than suck in current / power.

When the grid goes down, they power off just like any other AC appliance would (at least the simple GTIL1 & GTIL2 models which contain no integrated SCC…
 

BMcL

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Is there a way to tell the Growatt to use the Solar First, Batteries Second, and then utility?
This is also what I want to do using the MPP Solar LVX6048WP.
If the panels are not keeping up and batteries are getting low, can the grid help charge them and keep the critical loads up and running ?
Like in the winter if there were many cloudy days in a row ?
 

fafrd

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This is also what I want to do using the MPP Solar LVX6048WP.
If the panels are not keeping up and batteries are getting low, can the grid help charge them and keep the critical loads up and running ?
Like in the winter if there were many cloudy days in a row ?
The whole point of GTIL inverters is that they are in parallel with the grid.

Their are no ‘critical loads’.

There are just loads (whichever loads are connected to the wires being sensed, including the entire house).

When the GTIL senses power being consumed by the grid, it attempts to ‘push back’ by generating an equal and offsetting amount of power so all loads are powered by energy coming from the GTIL and grid consumption drops close to 0W.

When loads exceed GTIL maximum output levels (when starting a refrigerator or runnning an electric oven), the GTIL will max out, offsetting as much grid consumption as it can, and the grid will supply the rest (over either a shortterm motor startup burst or a longtime Turkey roast).

When the battery is drained and there is no incoming PV power, the GTIL will shut down and all loads will be powered exclusively from the grid.

GTILs allow self-consumption to be powered by solar energy with pretty much zero changes to home wiring (just a new breaker/circuit for the GTIL itself).

I was planning to go full hybrid (in-the-path inverter including transfer switches), but the cost of rewiring as well as the dependency on a new electronic ‘box’ in the primary power path are what steered me to GTILs instead.

They are not for everyone because they cannot be ‘official’ (at least not yet) but they are a true marvel for those of us who are comfortable going off the beaten path..
 

BMcL

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How do you identify an inverter that has GTIL ? Is an "AC input" indicative of it having this capability ?
The MPP Solar LVX6048WP has an "ac input"
LVX6048WP-2.png
 

fafrd

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How do you identify an inverter that has GTIL ? Is an "AC input" indicative of it having this capability ?
The MPP Solar LVX6048WP has an "ac input"
LVX6048WP-2.png
No clamp sensor - not a GTIL.

A GTIL will show a connection going to a clamp sensor located on one or both of the grid input wires (just behind the meter).

This is a hybrid inverter (as you can tell because the inverter(s) is (are) located between the grid and the load..
 

RememberTheMagic

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I thought the Growatt (or maybe it was some other brand) had current sensors that went on the mains to monitor the grid input and would tell the grid-tie inverter to cut back if it was getting ready to back-feed. I though that is what the OPer was asking about.
Exactly What I was looking for.

So who offers a grid tie that has the sensors and supports battery?
 

fafrd

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Exactly What I was looking for.

So who offers a grid tie that has the sensors and supports battery?

(But no integrated charge controller. Will run directly off of PV or off of a battery, but if using a battery you’ll need a separate SCC…).
 

RememberTheMagic

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I thought the Growatt (or maybe it was some other brand) had current sensors that went on the mains to monitor the grid input and would tell the grid-tie inverter to cut back if it was getting ready to back-feed. I though that is what the OPer was asking about.
Yes this sounds like what I am looking for. It seems in this setup I can (using only one breaker) backfeed the panel in the house and offset utility cost. Any extra power will charge the batteries, then shed pv input to zero (and batteries as well) in the event no loads are on.

I see this as an ideal way to lower power bill but still keep utility power for large loads and inrush current on motors, etc
 
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