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Victron Configuration Query


CDL

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Hi guys,

I have a Victron Quattro 10 kVA inverter combined with solar panels and battery array. I have a query as to how I can configure the application of the incoming solar power.

I let the system use the batteries down to 45% overnight, even though grid is available (the remaining 45% is "saved" for grid outage situations, the 55% usually being sufficient to carry us through the night). What happens is that in the morning the incoming solar power normally exceeds the AC loads. For example, as I write this, we have incoming photovoltaic of 2 kW and we have AC loads of 474 W. What is happening though is that the system is allocating the full incoming 2 kilowatt to charging the batteries and is drawing the 474 watts of AC load off the grid. 

This doesn't make sense because a little later in the day we will have excess photovoltaic power; in other words, later in the day the batteries will be fully charged and we will have more incoming photovoltaic power than we have AC loads. In other words, we will have solar power going to waste. It makes more sense to have the incoming solar power in the morning first service the AC loads and then use the balance to charge the batteries. This way we will be able to pretty much service the AC loads through the day and also across the course of the day get the batteries fully charged. I know this because I used to do this with the previous Axpert based system I had.

The simple solution – which I am using temporarily – is to simply switch the grid off, which then forces the system to 1st allocate photovoltaic power to the AC loads and the balance to the batteries but this is a bit of dumb way of doing things if the system can be configured differently. 

If anyone knows how this configuration can be changed and which element of the Remote Console settings need to be altered, I would appreciate your advice and input. 

Thanks in advance.

 

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14 minutes ago, CDL said:

I let the system use the batteries down to 45% overnight, even though grid is available (the remaining 45% is "saved" for grid outage situations, the 55% usually being sufficient to carry us through the night). What happens is that in the morning the incoming solar power normally exceeds the AC loads. For example, as I write this, we have incoming photovoltaic of 2 kW and we have AC loads of 474 W. What is happening though is that the system is allocating the full incoming 2 kilowatt to charging the batteries and is drawing the 474 watts of AC load off the grid. 

You didn't say if you are using ESS, but I have to assume that you are.

The control algorithm is extremely simply. When you reach the minimum state of charge (on the ESS menu), the inverter stops discharging the battery. All PV is then used to charge the battery until the battery is 3% above the minimum SOC. Then it switches back into self-consumption mode and all loads are powered from PV/battery. There is no gradual in the middle unfortunately.

So I take it that you end up in the morning with enough PV to power the loads, but because you are still within that 3% window, it charges the battery instead.

Since we're talking of a mere 3% of SOC, the amount you stand to gain by moving to self-consumption earlier (and reaching a full battery later) is very little. Take 3% of your battery storage capacity, that is how much you stand to gain in self-consumption.

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Thank you Plonkster.

Your assumption that I am using ESS is correct.

I have noted that now that the batteries are at 57% and I have put the grid back on, it is doing exactly as you say. I am not sure why it was not doing this once the batteries got to 47% as the threshold for them is set at 45%. Will keep an eye on it and see what happens.

Cheers and many thanks again! 👍

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4 minutes ago, CDL said:

Thank you Plonkster.

Your assumption that I am using ESS is correct.

I have noted that now that the batteries are at 57% and I have put the grid back on, it is doing exactly as you say. I am not sure why it was not doing this once the batteries got to 47% as the threshold for them is set at 45%. Will keep an eye on it and see what happens.

Cheers and many thanks again! 👍

Also have a look at the Active SOC, this varies. Sometimes 5% other times they are equal.

image.png.aff5d8aa2a70562e02f29a38de0abdf7.png

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1 minute ago, CDL said:

I have noted that now that the batteries are at 57% and I have put the grid back on, it is doing exactly as you say. I am not sure why it was not doing this once the batteries got to 47% as the threshold for them is set at 45%. Will keep an eye on it and see what happens.

It's not too much of a mystery. That part of the code is open source. Here it is: https://github.com/victronenergy/dbus-systemcalc-py/blob/master/delegates/batterylife.py#L252

It is essentially a state machine with deterministic transitions between the states. Making the switching offset smaller than 3% has the tendency to causes systems to flop back and forth between grid and PV/battery, so that number is one that works well for most systems.

The batterylife algorithm also 'interferes" with this. If you enable BatteryLife your MinSOC is adjusted upwards every day that the battery doesn't reach at least 85% SOC. If the battery wasn't fully charged today, it will stop 5% earlier tonight in an attempt to get a full charge tomorrow. Once it gets a full charge (above 95% SOC) it will move the SOC down 5% every day in order to increase self-consumption again, down to the minimum configured (45%).

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1 minute ago, PaBz0r said:

Also have a look at the Active SOC, this varies. Sometimes 5% other times they are equal.

Indeed, that is BatteryLife. If you select the "without BatteryLife" option, it doesn't show this and always switches on the MinSOC.

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