question

Hi @zed must

Not sure I'll have time but thought I'd ask a few questions (that I imagine anyone willing to help might want to ask anyway which might give people the extra info they need to offer their services).

1. What is your plan for how to adjust the parameters? Do you need/want a dashboard created in node red to adjust these, or do you have another system ie homeassistant/openhab that you'd want to utilise to update the SoC, time and i assume charge/discharge.

2. How is the system currently configured, is the solar connected via charge controller (DC coupled) or via Grid tied inverter (AC coupled) or do you have both. (If it's just AC coupled there's a faster way to code it up I believe)

3. When you say export to grid which of the below do you mean (or do you mean a mix in which case another few parameters might be needed to select which one).

• Export any excess solar only
• Export all solar (so loads will be powered from battery)
• Export a fixed number of amps/watts so solar + battery
• Export so that grid setpoint = a specific negative number

4. In terms of turning off this feature. (less applicable if your answer to 3 is excess solar only)

ie feature turned on if SoC > 50% after 7pm.

do you want off to occur only when SoC < 50% or at 5am or after x hours.

Here's some code:

I know the below is instructions rather than an easy install but it's free....

EDIT: You might have to change this is you ever want to manually make grid setpoint greater than 0. As this code will override it back to 0.

You need to do a few things first:

1. Get the data from victron nodes:

So you need to find the node that outputs the AC Solar data (PV Inverter node, then select measurement of power) as well as the DC solar data (likely Solar charger node and select measurement of PV Power). If you've got multiple MPPTs let me know i can edit the code to have multiple dcSolar variables.

And finally you do the same with State of charge data (likely from battery monitor node selecting measurement state of charge %).

2. These data nodes need to be passed into their own change nodes so you can set the topic of the message (this tells the function what type of info it's received.

It'll look like this:

With the inside of the change node looking like this:

You repeat this process for the DC solar but change the topic name in the change node to dcSolar and soc for battery monitor

You string them together like this:

Function 2:

//setting up time variables
var currentTime = new Date();
var hours = currentTime.getHours();
var minutes = currentTime.getMinutes();

//setting up data variables. If using up to date venus os you could get these directly via global context. 
var soc = global.get('soc');
var acSolar = global.get('acSolar');
var dcSolar = global.get('dcSolar');
var gridSetpoint = global.get('gridSetpoint');

//setting soc variable depending on inputs from flows
if (msg.topic === "soc") {
  soc = msg.payload; // Extract payload from input 1
  global.set('soc', soc);
}

if (msg.topic === "acSolar") {
  acSolar = msg.payload; // Extract payload from input 2
  global.set('acSolar', acSolar);
}

if (msg.topic === "dcSolar") {
  dcSolar = msg.payload; // Extract payload from input 3
  global.set('dcSolar', dcSolar);
}

//this is used to check if gridsetpoint is already 0, if it is then we won't bother updating it.
if (msg.topic === "gridSetpoint") {
  gridSetpoint = msg.payload;
  global.set('gridSetpoint', gridSetpoint);
}

if (msg.topic === "acLoad") {

  acLoad = msg.payload; // Extract payload from input 2

  global.set('acLoad ', acLoad);

}

//two examples of times
if (hours >= 10 && hours < 14) { //if time is between 10am-1.59pm
  if (soc > 70 && acLoads < 10000) { //if state of charge is above 70%
    //return the new grid setpoint
    gridSetpoint = -Math.min(acSolar + dcSolar, 6000);
  } else {
    gridSetpoint = 0;
  }
} else if (hours >= 14 && hours < 19) { //if time is between 2pm and 6.59pm
  if (soc > 50 && acLoads < 10000) { //if state of charge is above 50%
    //return the new grid setpoint
    gridSetpoint = -Math.min(acSolar + dcSolar, 6000);
  } else {
    gridSetpoint = 0;
  }
} else if (hours >= 19 && hours < 23) { //if time is between 7pm and 10.59pm
  if (soc > 30 && acLoads < 10000) { //if state of charge is above 30%
    //return the new grid setpoint
    gridSetpoint = -Math.min(acSolar + dcSolar, 6000);
  } else {
    gridSetpoint = 0;
  }
} else {
  gridSetpoint = 0;
}

if (gridSetpoint !== global.get('gridSetpoint')) { // Check if gridSetpoint is going to change
  global.set('gridSetpoint', Math.min(gridSetpoint, 0));
  msg.payload = Math.min(gridSetpoint, 0);
  return msg;
}

At this stage the function will output a message of what to set the gridsetpoint to. However before you pass this function into the ESS gridsetpoint node (to set the grid setpoint). You should test the code works as expected on your system/there aren't any bugs in it. To do this you should pass function into a debug node like below. And watch the outputs at various times of the day. Once you're happy that the function is outputing the correct negative number at all points in the day then you can pass the function into the ESS grid setpoint node.

I've hopefully written the code so you can see what hours you need to change and SoC to get the desired times.

As i said the debug would be replaced with grid set point node once you've confirmed function 2 is outputing what you expect.

@zed must

Clarity needed, Your example of

If SOC > 50% and time is after 7pm send PV to grid.

Do you have PV after 7pm?

1) Are you only feeding in PV or are you wanting to feed-in stored battery energy during peak periods where the feed-in tariff is at its highest then recharge the batteries during off peak at the lowest tariff.

2) do you want to limit the maximum feed-in power.

Settting the minimum SOC through the node red dashboard is easy and you can set as many set points as you wish, I change the minimum SOC every hour to crate a slow discharge through the night to make sure I don’t deplete the battery in the first 3 hours. I then bring up the minimum SOC hourly during the day which usually lags the actual SOC on sunny days how ever on over cast days the internal battery charger initializes to charge from the grid if there is insufficient Solar on overcast mornings, after mid day when the sun is up high the actual SOC overtakes the hourly minimum SOC again, so no charging from the grid takes place.

Setting PV Feed-in at different times as well as the feed-in amount in watts is also quite easy, Discharging the batteries into the grid is also easy to do by just setting a negative grid set point which will deactivate when the minimum SOC is reached.

The problem comes in when you have to limit the maximum feed-in power from the batteries. It can be done, I have done it but the amount of writes to the GX flash memory is quite a lot, every 2 or 3 seconds you need to write a new grid set point taking into account your current load on the AC-out of the inverter, AC-in to calculate internal loses as well as include any grid loads before the inverter if you have an external energy meter who’s roll is set as grid meter