Optimizing Victron DESS in Ukraine: Balancing Grid Feed-in, Battery SOC, and Resilience

Hi everyone,

I’d like to share some insights and observations regarding DESS mode optimization, particularly relevant for those of us in Ukraine navigating the complexities of grid feed-in limitations, battery SOC management, and the need for grid resilience. Many of us are grappling with the trade-offs between “Green” and “Trade” modes, and how to effectively manage battery discharge to maximize solar utilization.

Our specific challenges include:

  • Green Mode Limitations: While Green mode prioritizes higher battery SOC, it often leads to PV throttling when the battery reaches 100% SOC and grid feed-in is limited.
  • Trade Mode Drawbacks: Trade mode maximizes grid feed-in but can deplete the battery too quickly, even during off-peak hours.
  • Time-of-Use Tariffs: Day/night tariffs offer opportunities for strategic battery charging, especially during winter months.
  • Grid Outage Risk: The ongoing threat of grid outages due to russian attacks on energy infrastructure necessitates maintaining a higher battery SOC, particularly in the mornings.

My test setup comprises:

  • 23.09 kW of PV solar arrays (facade and roof mounted)
  • 6 kW grid feed-in limit
  • Two Multi RS inverters (combined ~11 kW grid/load capacity)
  • 58.5 kWh battery bank
  • Daily consumption ranging from 30-60 kWh (28 kWh in summer, 64 kWh in winter)

Through VRM data analysis, I’ve found that a hybrid approach works best:

  • Cloudy Days/Winter: Green DESS mode combined with scheduled “Keep charged” mode at night is ideal. DESS alone is often too slow to adequately charge the battery overnight for morning readiness.
  • Sunny Days (including Winter): Trade DESS mode is preferable, but only when coupled with a dynamically adjusted batteryDischargeRestrictionSchedule. This schedule should allow battery discharge (restrict: false) during daylight hours and restrict it (restrict: true) at other times. This prevents premature battery depletion before the cheaper night tariff kicks in and allows Trade mode to effectively spread grid feed-in across unrestricted hours, minimizing PV throttling at 100% SOC.

A significant issue is that the batteryDischargeRestrictionSchedule doesn’t automatically follow sunrise/sunset times, requiring manual VRM adjustments.

To automate this process, I’ve developed Node-RED flows:

I welcome your feedback, suggestions, and questions. Let’s discuss how we can further optimize DESS performance in these challenging conditions.

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Respect just for thinking about sharing knowledge under the pressure the country is! Thank you.

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