How Load Shedding Works in Smart Energy Systems

Introduction

With rising electricity costs and solar adoption at an all-time high, smart energy management is no longer optional — it’s essential. One of the most powerful tools in modern energy control is automated load shedding.

But what exactly is load shedding? And how does it work inside real buildings using platforms like WAGO, KNX, or Modbus-based PLCs?

Let’s break it down.

What Is Load Shedding?

Load shedding is the process of automatically turning off or reducing non-critical electrical loads when energy use approaches a limit — whether it’s due to solar generation dropping, battery state-of-charge falling, or grid draw exceeding a threshold.

It’s essentially a smart energy traffic controller: keeping essential systems powered while pausing or throttling the ones that can wait.

Why It’s Important

Without load shedding:

• Solar buildings can accidentally draw high tariffs during cloudy periods
• Battery backup systems can drain too quickly
• Sites can trip breakers or incur excess demand penalties
• Generator or off-grid systems can become overloaded

With proper automation, load shedding prevents these issues silently, keeping your building energy-smart without impacting user experience.

How It Actually Works (in Plain English)

Here’s how a typical load shedding logic works:

1. Sensors and meters monitor real-time power usage, battery charge, solar production, and grid import/export.
2. The controller (like WAGO) constantly checks if a threshold is being approached (e.g. 60A total draw, or 90% inverter capacity).
3. If the threshold is breached, the system shuts off predefined “non-essential” loads in tiers — such as pool pumps, EV chargers, or air conditioning.
4. Once demand falls or generation improves, the system automatically restores those loads in order of priority.

All of this happens based on rules you define — and it can be monitored and adjusted through dashboards, BMS platforms, or touchscreens.

Typical Load Tiers

Tier 1 – Critical (Never Shed):

• Fridges, medical devices, security systems

Tier 2 – Conditional (Shed Above Limit):

• Air conditioning, lighting, hot water

Tier 3 – Non-Critical (Shed Early):

• EV chargers, pool pumps, outdoor lighting

Real-World Applications

🏢 Commercial Building with Solar

• Sheds tenant aircon if grid draw exceeds 75A
• Resumes cooling once usage drops back below limit
• Balances solar vs load in real-time to maximise self-consumption

🏠 High-End Residential with Battery

• Shuts off pool heating when battery SOC drops below 25%
• Schedules EV charging to run only during solar peak

🏗 Multi-Unit Apartment Block

• Monitors each unit's common area power draw
• Disables outdoor lighting or exhaust fans temporarily when load is high

Load Shedding with WAGO, KNX, and Modbus

At Circuit Logic, we program WAGO PLCs, KNX logic blocks, and Modbus-based systems to perform intelligent load shedding using:

• Real-time CT metering
• Solar inverter data
• Battery state-of-charge input
• Override switches and priority control
• WebVisu or cloud dashboards for management

Whether you’ve got a basic solar system or a full BMS, we can integrate load control logic that protects your equipment and keeps your costs down.

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