elaborate-routine

Using the Agile scheduler I had a charge session finish at 6am immediately followed by a hold session starting at 6am. Both are in the WW log and the GE log. The hold correctly wrote the discharge power to 0 at 5:58 but this was trounced by the end of charge instruction which wrote the discharge power to 3KW at 6:02.

What I don't understand is why the end of charge instruction has to touch the discharge power at all? For the time being I have changed the hold start time to be five minutes after the end of charge time

    WindyMiller What I don't understand is why the end of charge instruction has to touch the discharge power at all?

    You're right it shouldn't do, it was there for resetting discharge at the end of charges that are part of a Hold window, but shouldn't have happened here.

    Fix being rolled out for this now, available in next 5 mins.

      admin Thank you.

      It looks like the next hold I had scheduled at 13:05 didn't send anything to the inverter so it didn't hold but WW did send something at 15:32 which was the end of the hold schedule. Is this another problem or a consequence of the fix for the earlier issue?

        WindyMiller Hmm, looks like a different and very specific problem when having an Agile charge window with 0 slots and Hold enabled. Will take a look.

        Update: This has been fixed and rolled out - server fix only. Agile charge windows with no charge slots and hold enabled will now hold the battery.

          admin I do seem to have a knack for finding these corner cases.

          What I'm trying to achieve is to charge over night using the 7 cheapest slots. Then hold the charge for specific windows when it would be cheaper for me to use the grid rather than the stored charge. This is due to the losses of putting units into the batteries and then taking them out again. I am assuming 20% is lost in the batteries so if I charged in a 20p slot I would hold that charge until the slots went above 24p (20p x 120%) before turning hold off. Then if, later in the day, prices came down below 24p I would hold the charge again. I'm only doing this for reasonably long times as really I want to be able to choose charge, hold or export in each half hour but that isn't possible at the moment. My batteries are struggling to get through the whole day without a top up charge or some hold periods as I hardly get anything from the panels on some days and I really don't want to run out during the 4pm to 7pm peak period.

            admin This has worked fine today. Hold correctly set from 11am without any charging slots enabled. Even better is that the sun is out but if it wasn't the hold would allow the remaining battery charge to reach 7pm.

            WindyMiller I don’t think this is logical, because the power you have put in to your battery at a cost of 20 / 24p is a sunk cost. Its value is not how much it cost but its replacement value.

            Let’s suppose that in the next period the import price is 15p, but in the following period it is 10p. Your stored unit is worth 15p if used immediately, falling to 10p in the next period.

            You would be better off discharging immediately in the 15p slot and then recharging and consuming from the grid in the 10p slot.

            Think of one unit of power in the battery and consumption of 1 unit per slot. In my scheme you will spend 20p over the slots by both consuming and charging in the second slot. In your scheme you will spend 25p by consuming 1 unit in each of the 2 slots. We both finish with 1 unit of charge in the battery.

              kerregan Sorry I wasn't very clear what I meant. Your example isn't what I am trying to do.

              What I wanted to say was that if I charge the battery in a 20p slot I will hold it there and use the grid for the next 'n' slots until they rise above 24p. Effectively I count the stored charge in the battery as costing 24p taking into account the losses even though it actually cost me 20p. I am looking ahead at what's coming up so know that I might be storing this unit until the most expensive slots in the day.

              If the slot prices are going down rather than up I wouldn't be charging in the 20p slot but in the later cheaper ones.

              My goal isn't to charge the battery to full but to cover the most expensive slots in the day (allowing for the 20% losses) from the cheapest slots in the day. If the whole day had slots within that 20% band I wouldn't want to use the battery at all.

              My analogy might be that if the slots cost 20p, 23p, 23p, 30p and I used 1 unit for the house in each slot I would add one unit to the battery in the 20p slot, hold it there in the 2x23p slots and then use it in the 30p slot. This would cost 2x20p + 23p + 23p = 86p. If I used the stored charge in the next immediate slot after charge (i.e. without holding it) this would cost 2x20p + 23p + 30p = 93p. Both would have losses of 4p for the unit that was briefly stored. But if all the future slots were 23p then I would hold that unit in the battery indefinitely (until the next day when I know what they next set of prices are). At that point it will become a sunk cost.

                WindyMiller Yes, the decision is entirely based on whether the price is rising or falling.

                If rising, you should hold charge and hold. If falling, you should discharge.

                This is why it makes no sense when people ask for or use features such as always charge if price is below x, even if x is negative.