Hi there, have been running my system for 2 years now here in New Zealand. Just recently got the whole system online and have started optimizing the DESS in trade mode. So far finding zero logic around the battery - grid exporting that can be comprehended by this mere human. So, I turned to AI and have been running historical data and realtime charts through it, trying to find patterns that could identify the logic. So far I’ve come up empty there as well.
Are there any other humans out there experienced with DESS logic that have a chance of making sense of the results I’m seeing? I’m definitely losing $$ everyday.
Ah so it’s fixed time of use tarrifs not the dynamic pricing that changes crazily.
So with that then sometimes it’s a combination of battery cost Vs perceived profit. It may be that the system is thinking it’s not worth selling the battery as the grid is cheaper.
Is there a reason why you aren’t just on self consumption?
We use such a small amount of power on our property, that the batteries are full by 830 or 9am. The rest of the day the PV exports to grid. But the peak time to earn is evening and morning, and I thought that the DESS would sell battery power to the grid. It did on Oct. 16, 23 and 30th (all Fridays), and it looks like the scheduler is planning another export tomorrow (Tuesday). But so far I haven’t been able to figure out why these three times it did export as hoped for, whereas all the other days it didn’t.
I checked your data and settings. DESS follows your tariff correctly. On weekdays the battery refills the next morning during the 0.21 sell peak, so selling it the evening before gains nothing once battery wear is counted. On Fridays the next day sells at 0.16, so it exports. An export planned for the last evening of the schedule usually disappears the next day.
Could you check two settings against your tariff? Your prices should include GST, and the sell peak is only set on weekdays. If you still see something odd, please share the date and time so I can look at that moment.
Something interesting happened today that I’d like to understand.
This morning, the DESS schedule for tomorrow (Tuesday 3 November) showed battery-to-grid exports during the evening peak period, particularly between 20:00 and 21:00.
I checked again this afternoon, and the battery-to-grid export had completely disappeared from the schedule.
I’ve attached both screenshots. The energy price forecasts appear identical in both.
Could you explain what caused DESS to change its decision?
Is this an example of the scheduling horizon rolling forward and the optimisation recalculating the economics, as you mentioned previously? Or has something else changed in the underlying forecast or calculation?
I’m particularly interested in understanding what variables changed between the two calculations, given that the displayed energy prices remained the same.
If possible, could you also explain whether there is a way to inspect the inputs or reasoning behind these schedule changes?
I’ve updated my price including GST:
The key question for Victron is whether DESS should be given the gross tariff or the net amount actually credited after network charges?
This is the horizon rolling forward. This morning the schedule ended at Tuesday 21:00 and could not see Wednesday morning’s peak. Selling the battery on that last evening looked profitable. Once the schedule reached Wednesday, refilling during the morning peak cancelled the gain, so the export was dropped. Your prices did not change, only how far ahead it could look.
About the new prices: everything went up 15% except the weekday peak sell, which went from 0.21 to 0.20. Should that be 0.24? At 0.20 the peak is barely above the off-peak price, so DESS will likely not sell the battery at all.
I added the GST, but then realized that my network charges a “peak export charge” of $0.0359c So actually the price dropped.
I guess that’s a question for Victron is whether DESS should be given the gross tariff or the net amount actually credited after network charges?
Give DESS the net amount: what you actually receive or pay per kWh, including GST and any per-kWh network charges. Leave out fixed daily charges. So your 0.20 is correct.
With that, the peak export earns only about 1.6c more than off-peak, which is less than your battery cost setting. DESS will now mostly keep the battery for your own use and export solar directly. That is the right call for this tariff, not a fault.
Thank you for the concise answers. I’m disappointed to learn that there is no incentive for me to export at peak times to the grid, it seems like such a waste. Like being dressed up with nowhere to go! Oh well, I guess I should’ve learned about this before I bought 40kwh worth of batteries.
So essentially the system is set so the only time it will export is on Friday evenings IF the Saturday price is lower.
Close, but with your new net prices even Friday no longer pays: selling at 0.20 and refilling from solar worth 0.184 gains 1.6c, less than the battery cost. So expect no battery export at all with this tariff.
The batteries still earn their keep: every kWh you use from them at night or in the morning peak saves you 0.233 to 0.329, which is worth far more than exporting it. And you have backup when the grid fails.
