Load shedding is the intentional, temporary reduction of electrical power supply to certain appliances and/or circuits. This is done to reduce electrical consumption and is a cost saving measure. Load shedding helps to balance supply and demand, ensuring the stability of the overall electrical system during times of high demand or when there are issues with power generation.

https://www.youtube.com/watch?v=VvCU27lj3rU

Why use a Script for Load Shedding?

Using a script running on a Shelly Pro 3EM has a lot of advantages, especially when combined with various other Shelly relays. Scripting can offer a highly customizable and extremely efficient way to accomplish load shedding. A script either from the repopulated Shelly library or manually entered is used to create a system where you can dynamically control and shed loads based on certain conditions, such as high energy consumption or demand.

Prerequisites

Shelly EM Devices

These devices will be used to gather the consumption data required for load shedding

Shelly PM Devices (Optional)

PM devices can be used to gather additional consumption data and control circuits during shedding.

Additional Shelly Relays

These devices will be used to control various loads during shedding.

Steps to Setting up Load Shedding

1. Setting Up Shelly Pro 3EM

Wire and Configure the Pro 3EM

Install and Configure: Install the Pro 3EM per the diagram below to monitor the energy consumption of the entire home.

In scenarios where CT-B is not used, it is advised to repurpose it to cover Neutral. This requires recalibrating in the device’s settings.

Legend

Terminals		Cables
A	Phase A input	LA	Phase A live (110-240 V) cable
B	Phase B input	LB	Phase B live (110-240 V) cable
C	Phase C and power supply input	LC	Phase C live (110-240 V) cable
N	Neutral terminal	L	Mono-phase live (110-240 V) cable
IA	Phase A current transformer input	N	Neutral cable
IB	Phase B current transformer input	Current transformers
IC	Phase C current transformer input	CTA	Phase A current transformer
IN	Neutral current transformer input	CTB	Phase B current transformer
		CTC	Phase C current transformer
		CTN	Neutral current transformer

Connect to Network: Using Shelly Smart Control, connect the Pro 3EM to your network.

Shelly Cloud (optional): Add Shelly Pro 3EM to a Shelly Cloud account for remote access.

2. Set Up Additional Shelly Relays

Install Shelly Relays: Install Shelly relays to control the specific loads you want to manage.

https://kb.shelly.cloud/knowledge-base/

Connect to Network: Using Shelly Smart Control, connect the Pro 3EM to your network.

Shelly Cloud (optional): Add Shelly Pro 3EM to a Shelly Cloud account for remote access.

3. Adding the Load Shedding Script to the Host Pro 3EM

Navigate to the Scripts Menu: Shelly Smart Control has a section for Scripts for each compatible device. For Load Shedding we will use a Shelly Pro 3EM. With that device select click on the { } Icon.

Click Open Library and Select the Script: On this screen we will select; Load Shedding with Shelly Pro 4PM and Pro 3EM. Expand this option and press the button labeled Insert Code

Name the Script: At the top of the screen give your script a name.

Setting the Devices to be Shed: The devices to be shed are specified under first_to_last_to_shed

Configuring the Shedding Trigger Parameter:
1. max_before_shedding

Configuring the Reading of Devices:
1. min_before_re_adding

Configuring the Polling Frequency:
1. poll_time
  1. Minimum interval between executing normal on/off steps
2. short_poll
  1. Interval after toggling on a device assumed to be already on

Set Logging Parameters:
1. logging
  1. will populate the Activity Log

Set Simulation Parameters:
1. simulation_power
  1. Set this to manually test in the console

Saving and Executing the Script:
1. Click the Save Button in the top right next the the Script Name and Play Button
2. Click the Play Button in the top right next to the Script Name.

5. System Testing

Simulate High Load: Increase the load to trigger the thresholds.
Verify Script Actions: Check if the Activity Log to verify the Load Shedding Script is executing the defined commands.

By following these steps, you can effectively use a Script with Shelly Pro 3EM and various Shelly relays to implement load shedding, helping to manage and reduce energy consumption dynamically.

Shelly USA Documentation Library

Basic Load Shedding Using a Script

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