• General
  • Why does my export stop early ?

Now that we have plenty daylight, I'm starting to remark that my export cuts of early (a lot too early) more and more.

My export window in WW is set from 16:25 to 19:00 and the export limit is to not drop below 12%.
However the WW prediction makes it stop at 18:44 with plenty of juice left (29%).

This has been happening over the last few weeks. I tried to make the window even longer by moving the start time forward in time and leaving 19:00 as end time. I played with the battery adjustment multiplier upto 1.2 instead of 1.0 and no difference.

I have the impression that the algorithm does not take into account the amount of PV created between 16:25 and 19:00. This is not to be neglected (especially with my second NW facing area which is kicking in). It feels that the more PV is generated in that period, the earlier the algorithm cuts off the export and leaves energy in the battery that I want to export (at Octopus flux peak rates).

What's behind this ?

    JMA Do you have a DNO export limit set? We simply assume the battery can dump at full rate and calculate the proportional time it would take to reach target SOC based on current SOC just a min or two before export start.

    I guess the other main thing is, with solar coming in, the inverter's capacity is effectively used by solar DC being converted to AC and that may limit the rate of battery DC->AC at which you can export...

    Hmm. What we don't want to to is check every few mins as to what your SOC is. Seems wasteful and with lots of users exporting we'd worry about excessive API calls - there's plenty going on already as it is.

    • JMA replied to this.

      admin
      There's no DNO export limit set.
      It is then indeed the solar that gets converted to AC and directly exported to the grid together with what the inverter can handle to send to the grid.
      The challenge is hence the calculation to set the end time. I don't think there's a need to check the SOC every few minutes.
      I think you can either:

      a) 5 or so mins before the calculated end time verify the SOC once and if that if still too far from desired SOC at end time, just extend the end time once linearly.
      b) look at the solar forecast between start and end date and add that value to calculate a new end time

      Both should be pretty straight forward. a) is likely much easier to program.

      As summer is around the corner, this will gradually gets worse. I'm now already not using 20% of the capacity of the battery that I could sell. As daylight gets longer and longer, then will just increase.