Oh, my mistake, I missed your post, but it is exactly the same problem, so the implementation is obviously not correct. Also I think, that behavior of Trade mode in case of negative prices is not correct for that reason, because if price became negative, the goal should be cover consumption and also charge the battery from grid, not from PV (I can imagine this in Green mode, but not in Trade mode).
I am using DESS in Trade mode, because I want to feed-in PV energy directly to grid in case of higher positive price (especially in the morning) and after that when price drops use PV to charge the batteries. Second benefit should be to use as much energy from grid as possible in case of negative price to get better final energy bill (obviously :–) ), to help stabilize the grid (when there is a lot of excess energy) and to not use PV (extend the life of solar panels and MPPTs).
I think there is an issue with the presentation of the numbers in VRM, but I’m not sure if anything is wrong with DESS itself. I don’t see strange behavior with negative prices myself. That your PV is used to charge the battery when prices are negative is not necessarily incorrect, the PV energy has to go somewhere.
No, in this case PV power was not used to charge the batteries, but to cover the consumption, which is in my opinion wrong behavior in case of negative price. Better behavior is to use grid and don’t use PV (for reasons I wrote - grid stabilization, extending lifetime of MPPTs/solar panels and better energy bill which should be the goal of Trade mode). Charging the batteries was done in next hour also with help of PV power.
What do you mean by “don’t use PV”? If you don’t want to use PV when the price is negative, you should switch it off, otherwise the energy is being produced and it needs to go somewhere: consumption, battery or grid.
For my opinion, it is not necessary to use PV all the time if it is available, especially if there is better/cheaper source at the same time = grid in case of negative price. DESS should use as much energy as possible from the grid and automatically limit power from MPPTs (if the consumption is over the set grid limit, PV could be for example also used to charge the batteries), which is probably what you are doing in the Node-RED, isn’t it?
Yes, I have SolarEdge AC-coupled PV, connected via Modbus/TCP, which DESS is not (yet?) able to limit, so I’ve created a node-red flow for that. If you have MPPTs from Victron, they could/should indeed be reduced in power by DESS.
Yes, this should be reduced with Victron MPPTs, but the reality is different… 
I also made a lot of another automations in Victron system by Node-RED, so probably I will have to do also something about this 
Thank you Victron staff for fixing wrong calculation in VRM!
And what about the second thing about using power from PV instead of using power from grid in case of negative price? Is it something which should be already implemented in Trade mode of the DESS or it could be something to add on To-do list? 
Today during negative grid prices same very bad behavior of DESS. I have implemented in Node-RED switching off all MPPTs in case of negative prices, but DESS still use battery instead of grid.
Why? Why DESS uses PV or battery instead of using grid when price is negative? This completely makes no sense, especially in Trade mode…
Victron team, please take a look at it and change/fix this wrong behavior.
Hi there,
Unfortunate that on days with negative prices, Dynamic ESS does something you don’t expect it to. Could you share your installation url, so I can ask someone on the team to take a look for you?
Kind regards,
Barbara
Hello @Barbara,
thank you for your effort.
DESS has information about negative price and the goal in Trade mode should be final bill as low as possible, so using PV or battery instead of grid during negative price does not meet this goal completely…
I will try (in addition to switch off the MPPTs) also change battery mode from Optimised to Keep batteries charged during negative price, which should help to achieve correct behavior, but DESS algorithm should have implemented using grid during negative price.
My installation ID is 152686, but I expect negative prices no earlier than Sunday, yesterday were negative prices due to Labor Day.
Hi @Barbara, I have the same questions.
Tomorrow the price will be negative for three hours in the Netherlands.
My system is three Multi RS’S with Cerbo.
Id: 356542
It looks like DESS will stop using energy from the PV in the third hour (when the batteries re full). But in my opinion it should not use PV power from the Multi RS’S all three hours, and charge from grid only when prices are negative.
And the system acted exactly like in the pictures. The first two hours with negative prices the battery was charged with power from PV an grid. In the third hour, when the battery was charged to 100%, the PV production went down, and it went up again when the grid price was positive again. Why not stop the PV power all three hours with negative prices?
Not only for better financial gain. But also to improve grid stability. That way our battery uses pv-power from our neighbours.
Today, a few days after the day with three hours of negative prices (where pv Power was used to charge the battery), I see that the system is throttling down the PV production in the cheapest (but NOT negative) hour of the day, to charge the battery from the grid. In my opinion, PV production is always cheaper to charge the battery, than buying from the grid as long as the price from grid is not negative.
There is still room for improvement.
For me it’s the first time tomorrow with DESS facing negative hourly prices.
I’m running green mode and would expect it to charge with max power during that time.
But the DESS schedule says: consume from battery!!! (SoC is not reaching 100% according to VRM forecast so there is plenty of headroom for charging from grid with negative price!!!)
PV and battery are 100% AC-coupled, no DC-DC MPPT involved. My installation is VRM Portal - Victron Energy
Also in preparation for tomorrow, DESS could have throttled charging today to reserve more battery capacity 
As a workaround I just created an automation in Homeassistant which will push grid set point to +20kW when price is lower than -0,01EUR/kWh
We are encountering two problems with the current setup involving Victron SmartSolar and Fronius in combination with dynamic energy pricing.
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Solar Behavior at Maximum SOC:
When the battery reaches its maximum state of charge (SOC), the system correctly switches the solar production to self-consumption only when electricity prices become negative. However, even during negative pricing periods, the solar production is not being curtailed or turned off as expected. This results in excess energy being generated without economic benefit. -
DESS Timing and Minimum SOC:
The Dynamic ESS control starts selling energy too late. Because of this delayed reaction, the battery does not sufficiently discharge to the intended minimum SOC target. For example, today the minimum SOC was configured to 15%, but the system only discharged down to 40%. As a consequence, large parts of the day the solar installation had to limit or completely stop production, since the batteries remained too full.
407704
My observations from May 11th 2025
Negative prices occurred between 12:00 and 15:00. Charging started correctly at 12:00, but continued until 16:00, with a short pause around 14:00. As a result, the cheapest hours were not fully utilized. Charging continued even after 15:00, when the price was already positive.
Around 14:00, I manually activated 23 kW of additional load. Instead of drawing this power from the grid (which would have earned money), most of it came from the battery. This feels like a missed opportunity.
It would be great if solar production could be halted during these negative price hours.
VRM Site ID; 356642
