Unreliable Weather Forecast Causing Faulty DESS Predictions
After resetting the weather forecast data in Venus OS, the system initially provides a realistic forecast for about two days (e.g. around 20–25 kWh/day). However, after that period, it suddenly jumps without any clear reason to highly unrealistic values such as 90 kWh/day or more.
This has the following effects:
Dynamic ESS receives incorrect input, which leads to faulty assumptions about available energy.
Battery control decisions are then based on these unrealistic forecasts, resulting in premature or delayed (dis)charging.
The “Energy to be Expected” value inside DESS appears to partially track the forecast, making the behavior even more inconsistent.
These forecast values regularly exceed the physical system capacity. We are grid-connected with 3×25A, and actual production should never realistically exceed ~17.5 kWh/day.
This is not only confusing but leads to concrete inefficiencies and DESS behavior that is not aligned with system capability or grid constraints.
- Solar Behavior at Maximum SOC
When the battery reaches its maximum state of charge (SOC), the system correctly stops charging and prioritizes self-consumption — particularly when dynamic prices go negative. However, even during extended negative pricing periods, solar production is not being curtailed or turned off, resulting in unnecessary and uneconomical energy export to the grid.
We would expect Fronius and/or the MPPT to be throttled or disabled in such cases, but that is currently not happening.
- DESS Timing and Minimum SOC Not Respected
Dynamic ESS appears to react too late to pricing and weather signals. This causes the battery to remain at too high SOC levels during the early part of the day, blocking solar production later on.
For example:
Today’s minimum SOC was configured at 15%, but the system only discharged to around 40%.
This left insufficient buffer for solar generation, and the system had to limit or stop solar input during high production hours due to a full battery.
Request for Support
Could you please advise:
Is the weather forecast issue a known problem in Venus OS, and is there any way to force accurate or capped forecasts?
Why are Fronius and SmartSolar not being curtailed when prices are negative and SOC is full — is this a configuration issue or a limitation in current DESS logic?
We would appreciate any insight or workaround, as these issues significantly impact system efficiency and make automated control less reliable.
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