We are happy to introduce a new feature in Dynamic ESS that allows you to better align with the specifics of your energy contract. Some energy contracts set energy prices to ‘zero’ when they go negative, preventing customers from profiting from negative buy prices. If your contract includes this condition, you can now easily configure it within Dynamic ESS.
In the configuration settings, under the ‘buy’ and ‘sell’ prices sections, you will find a toggle that indicates whether your energy provider considers negative prices. By toggling this off, Dynamic ESS will automatically adjust calculations to use a ‘zero’ price per kWh whenever prices drop into the negative range.
This feature is flexible, allowing you to set this condition separately for buy and sell prices. If your energy provider allows negative sell prices but not negative buy prices, you can configure Dynamic ESS accordingly to ensure accurate pricing and optimal energy management.
Try out this new setting to ensure your Dynamic ESS is fully aligned with your energy contract terms.
Tried today - czech region - price “P” between 1PM - 2PM is “- 0.45 Kč / kWh”. I add to formula “+ 3,34” for service fees and multiply it with 1.21 for VAT. So the final price for me when negative prices are allowed is 3.5 Kč / kWh - which DESS shows correctly. But when I toggled that Negative prices are not allowed, it should show 4.05 Kč / kWh (0 + 3.34 * 1.21) but DESS graph shows the same value 3.5 Kč / kWh as it was when negative prices are allowed, toggled DESS On/Off, waited few hours, but the same value 3.5 Kč / kWh as it is not taking this option into account.
I am afraid this is intended behavior. As your nett price (including service fees and VAT) is still positive, DESS considers that rather than the ‘p’. Are you certain about the service fees? Do you receive those when you sell energy?
I am on fix tarif when selling, this is for buying and yes, final price is positive, but what I mention is that, that it calculates final price with “p” letting negative and if I understand this function correctly, it should make negative “p” to p=0 then add service fees and multiply it with VAT, which is not happening and it calculates the formula with original “p” which is for certain hours negative, but my provider does not accept negative “p” and instead of it he bills with “p” =0. But in buy price graph of DESS this is not taken in account, but it should when there is this new feature, which should do exactly that - if “p” is for that hour negative, make it zero and than calculate the formula for final price, which of course can result in positive, but higher value than if “p” would still remain negative.
For the moment, negative prices are not taken into account for Germany. Probably it will come next year for new installations. As the negative prices can be seen day ahead, DESS should also override the grid setpoint of ESS to dump the battery SOC to grid in advance. This allows to recharge battery while prices are negative. Otherwhile energy would be lost.
The price formula determines the price Dynamic ESS works with. So this feature was made so that when that price (from the total formula) is negative, we make it 0.
I can discuss within the team if we should change it to only look at ‘p’, I will get back to you.
Thanks for understanding the issue - it is exactly as you said - in our country (I think also in others) when billing energy prices at companies which does not allow negative price it works like that - they “zero” only “p” value and than they add other fees + VAT. They do not “zero” final price per kWh.
I was super excited when I read this announcement, however, I was a little bit sad when I realised that this is only available when selecting a dynamic provider and not when selecting fixed prices
Maybe i misunderstood the feature.
I am looking for a way to keep track month to month with energy imported and exported assuming the rates are fixed, and from here have a feature in the ESS to prevent that more energy is sold back to the grid than imported. Essentially so that the energy bill will always be positive or close to zero as possible.
I see. That is a useful feature, but indeed not the goal of this Dynamic ESS change. This feature is to support countries where energy providers do not support negative sell prices to the grid.
We will work on economic reports linked to Dynamic ESS in the future, and there you can probably keep track of how well Dynamic ESS does in bringing your energy bill to zero.
I have previously posted about importing my provider’s prices using their API and Node-RED. Today was a prime example of negative prices through the peak of the day’s solar production: I was being paid to use grid power at up to $0.30/kWh, but DESS wasn’t apparently able to make use of it.
Given I was also being charged $0.36/kWh to export my solar to the grid, I’d also like to think that DESS would throttle my Fronius inverters to zero and run off the grid.
Evidently that didn’t occur, so I went about adjusting setting the inverter’s AC Power limit to zero using dbus:
That works for a while, however, some minutes later, the inverters are set back to full-throttle (presumably by some part of ESS).
It doesn’t feel like an optimal way of handling the situation! Should DESS automatically optimise for the favourable grid pricing and negative solar feed-in prices when prices are set via the “fixed” mode? Trying to understand if this is a limitation of DESS or my misconfiguration.
What do you mean with the fixed mode for pricing? If you mean the non-dynamic prices, then unless you adjusted your price table to include the negative buy price, DESS indeed has no notion of the price turning negative.
If you could share your installation id through a private message I can probably provide you with a better answer though!
By “fixed mode”, I am indeed referring to non-dynamic prices: when I import prices from my provider’s API, it does include negative prices (for both buy and sell). I guess the issue appears to be that DESS doesn’t appear to be making appropriate decisions with that information.
I see private messages are disabled, @Barbara , but my VRM installation ID is 510670. Very grateful for your assistance and would be happy to chat further offline if required.
I think your issue on January 1st was mostly influenced by battery balancing combined with a slightly inaccurate solar forecast that day. As battery balancing couldn’t happen based on only solar, DESS chose to use the grid for part of the consumption.
Did DESS make odd choices for you in the days without battery balancing?
Thanks so much for taking a look. Scrolling back through the data, I’m struggling to find an example to point you to right now, I’m sorry! Most of the issue I have with DESS is decision making around negative prices, both for buy and sell.
For example, when grid buy is negative (i.e., I am being paid to use the grid), I do not see DESS make best use of that, preferring to use solar (and not necessarily maximise charging capacity even). Similarly, discharging into the grid when the sell price is negative (i.e., I am being charged to export to the grid).
I’ll keep looking into the history and find an example to share.
