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

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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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