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Grid tie inverter on separate battery inverter output


Noobie

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8 hours ago, Noobie said:

How would the Infini export power to these non essential loads but not not export it out to the grid?

Hi @Noobie. If you only have one DB, you can prevent the Infini exporting to grid by setting the settings. If you set it up as per your sketch, the Infini would see your House DB Box as Eskom. Therefore if you had excess power after feeding your Inverter DB box, it would export the excess power to the House DB box. If there is still excess power available after feeding the House DB box, it would go to grid. If there is a shortfall of power, it will draw power from the grid. In this case you cannot prevent feedback to the grid, unless you have a limiter installed (A) as marked on your sketch. 

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1 hour ago, Don said:

n this case you cannot prevent feedback to the grid, unless you have a limiter installed (A) as marked on your sketch

Far as I know the Infini can also be combined with an external modbus meter, though I have no idea how it works, if you need special firmware, or what. The "limiter" really is just a power meter that is used by the inverter to adjust how much it feeds back. It attempts to hold the meter around the zero point, more or less like the driver of a car attempts to hit 60km/h in town :-)

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3 hours ago, plonkster said:

Far as I know the Infini can also be combined with an external modbus meter, though I have no idea how it works

I have no idea either. I personally would not bother with it. I would store my excess power on the grid during the day and use it at night. It probably depends on your meter and your circumstances. If you have a prepaid meter, you would want to make sure no power goes back to the grid. 

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25 minutes ago, plonkster said:

2. They also have a feature called grid-assist, which is really the same thing, except this uses grid power to assist the inverter when the load is higher than the inverter capacity. Once again, this allows loads on output 2 that is higher than the inverter capacity, but those loads can still benefit from surplus power. They are simply disconnected if the grid fails.  

 

For example, if you have a 48/3000/35-50, that means 48 volt, 3000VA, 35 ampere charging capability, 50A transfer switch. Since most houses have only a 50A feed, that is perfectly suitable. 

Sooooo, if I install a 48/3000/50 directly after my ripple relay box and all my essential and non essential loads are connected to output 1 and output 2 respectively if the geyser turned on and pulled more than 3000VA, what would happen?

Would the unit go into bypass mode and connect the input directly to the 2 outputs? Would this would then mean that the outputs wouldn't be getting any power from the PV during the time that the geyser is on?

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12 hours ago, Don said:

Hi @Noobie. If you only have one DB, you can prevent the Infini exporting to grid by setting the settings. If you set it up as per your sketch, the Infini would see your House DB Box as Eskom. Therefore if you had excess power after feeding your Inverter DB box, it would export the excess power to the House DB box. If there is still excess power available after feeding the House DB box, it would go to grid. If there is a shortfall of power, it will draw power from the grid. In this case you cannot prevent feedback to the grid, unless you have a limiter installed (A) as marked on your sketch. 

@Don I guess I will have to do some homework and see if there is a grid tie limiter that works with the Infini. 

Does the Infini run without a battery bank connected? 

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14 hours ago, maxomill said:

2 it has a self consumption mode (it uses Eskom and subsidises this with solar , my Eskom usage  usually sits around 0 to 20 w during the day)( it also doesn't cycle the bats)

3 it has a gti function if you want it and that can be used to supply the rest of house  the geyser or what ever

if the power goes down during the day I barely notice it

also if you place a contactor in you circuit that is supplied by Eskom but controls some inverter circuits then it will auto switch off high usage loads during a power failure . this contactor could also be controlled by a the inverters  dry contact ( usually used to switch the genie on ) under the battery settings

 

I guess the only thing I would need to do is install a grid tie limiter at location A on my sketch and have it tell the Infini when to throttle back the export of power.

I dont want to trip my eskom meter 

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1 hour ago, Noobie said:

Sooooo, if I install a 48/3000/50 directly after my ripple relay box and all my essential and non essential loads are connected to output 1 and output 2 respectively if the geyser turned on and pulled more than 3000VA, what would happen?

Would the unit go into bypass mode and connect the input directly to the 2 outputs? Would this would then mean that the outputs wouldn't be getting any power from the PV during the time that the geyser is on?

That depends on what mode you run it in, but since we're talking in the context of grid-tied here, I will assume you'll be running ESS, which is Victron's acronym for Energy Storage System.

What ESS does that is slightly different to other GTIs, is it can also use battery power to feed the grid and lower/eliminate your consumption. As always, if you draw more than the inverter capacity, it takes the difference from the grid. Other than this, you can think of it as a hybrid inverter. I think it also differs from the Infini in this respect, though once again, I don't know that inverter well enough to say for sure.

Now to answer your question. If you install the Multi right there where your power comes into the house (more about that below), and you put all the essential loads on output 1 and the non-essential ones (aka geyser) on output 2, this is what happens.

1. If the geyser turns on and you use more than 3000VA overall, the inverter will run at 3000VA (roughly 2400W usually) and the difference will come from the grid.

2. If it is day time and you have PV coming in, that will of course be used by the inverter to supply the 3000VA/2400W load mentioned above.

3. If the overall load is below 3000VA, the inverter balances its output so that the grid consumption hovers around zero, so if you for example have 200W of essential loads and 500W non-essential loads at the time, it will push back 700W to cancel both out, so that no power is used from the grid.

4. If the power fails at any time, everything on output 2 is dropped and only the essential loads is powered from the battery.

5. If at any time the battery SoC drops below the configured minimum, the inverter goes into bypass mode and powers everything from the grid.

6. If the batteries have been in a discharged state for too long, it will switch to sustain mode and charge them from the grid.

Technically of course these features don't reside in the inverter, they are in the software that lives on the CCGX/Venus-GX, but that software is free and you can run it on an Rpi if you want to save some cash, so it is no longer an impediment :-)

About the installation of the Multi: I think the SANS rules for installing a UPS will apply, which means the Inverter must be protected by a RCD (residual current device, colloquially known as an earth leakage breaker), and if it feeds any sockets in the house (as it certainly will) it must also have a RCD on the output.

I distinguish between ELB and RCD because though both are a variant of the same kind of device, there are apparently breakers that operate on a voltage level on the earth connection, ie, there are ELBs that aren't RCDs :-)

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Here is a visual demonstration of what happens. I had my critical outputs bypassed at the time, so that indicates zero, but if I had critical loads at the time it would show up in that block and you'd see the power flow both ways.

If you look carefully, you'll see at times it overshoots a little (cloud edge effect), and it pushes back into the grid for a few seconds, and then you'll see it pull back. When there is surplus power, it goes to the batteries, when there isn't enough, it comes from the batteries.

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On 16/08/2017 at 3:24 PM, Noobie said:

So heres my simple sketch.

What I would like to have is an inverter which feeds power from the PV panels to the essential loads (lights plugs) and the non essential loads (stove, geyser) when there is enough PV power to do so.

I would imagine that some sort of smart meter that talks to the inverter would need to be installed at location "A" to tell the inverter not to feed back power back into the grid.

Then when the grid fails I want the inverter to supply battery and PV power to the essential loads only.

 

 

SMINOLTA17081617210.pdf

You are essstentailly trying to Do what SMA has in Normal configuration - A sunny Boy and Sunny Island . Look at SMA site to know further 

https://www.sma.de/en/products/battery-inverters/sunny-island-44m-60h-80h.html

 

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14 minutes ago, ghatikar said:

You are essstentailly trying to Do what SMA has in Normal configuration - A sunny Boy and Sunny Island . Look at SMA site to know further 

https://www.sma.de/en/products/battery-inverters/sunny-island-44m-60h-80h.html

 

That in turn isn't very different from the old Hub4 setup which became ESS. Victron simply uses Fronius inverters in their setup while SMA has their own.

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On 18/08/2017 at 8:21 AM, plonkster said:

Here is a visual demonstration of what happens. I had my critical outputs bypassed at the time, so that indicates zero, but if I had critical loads at the time it would show up in that block and you'd see the power flow both ways.

If you look carefully, you'll see at times it overshoots a little (cloud edge effect), and it pushes back into the grid for a few seconds, and then you'll see it pull back. When there is surplus power, it goes to the batteries, when there isn't enough, it comes from the batteries.

1

I have kept the Axperts ( 10 KVA infact) with the Victron 5 KW quattro on the same battery bank.  ( Axpert represented by DC Power ) 

I am not Using ESS mode but Ignore AC setting so there is never aan export - ESS  does not work reliably with Niegrain grid as grid is missing 70 & of teh time !!

See video Below 

In Ignore AC assistant till the batteries are charged above 90 % SOC the Quattro takes the power from PV and battries through DC bus. If the SOC drops below 90 The Quattro reverts to Grid till Batteries are 100 % .( Since the SOC figures come from BMV 702) they are pretty reliable  The  Ignore AC mode runs only between 8 Am to 4 PM ( max production time)

 The Axperts rely on their Built in SOLAR mode controlled from ICC using SOC and time of Day 

As an additional kicker I have also AC coupled a small 500 Watt Micro Grid inverter on the output of Quattro- So normally  the House is supplied by the micro inverter Directly providing max efficiency 

Due to some vacation Kids are at home otherwise the House load is supplied by Grid inverter and Quattro and axeprts contributing only when loads are higher such as washing machine or kitchen appliances 

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