Introduction

Presentation

This software is an Open-Source Home Energy Management System based on [Home-Assistant](https://www.home-assistant.io/) installation. It all run locally witch is good for privacy and is customizable. The role of OpenHEMS is to schedule all heavy consumption appliance at the best time.

This software is usefull to get an as smart as possible management of power consumption and production. This should lead to cost reduction.

  • If you have a solar panel with battery, it will allow you to have smaller battery (witch is the most expensive part).

  • If you have a public power grid source with variable cost, it will allow you to consume when it’s lower cost.

Warning : This software is under activ developpment and is used on production but remain at early developpment. All contribution to the software are welcome. Please contact contact@openhomesystem.com for any questions.

# Architecture

OpenHEMS is not another home automation platform. It is an Energy Management System (HEMS) that sits on top of your home automation system and makes optimization decisions.

Rather than directly interacting with devices, OpenHEMS continuously evaluates the state of your home, forecasts future energy availability and demand, and determines the best time to operate flexible loads.

```

+——————-+ +——————-+ | Internet | | Home-Assistant | +——————-+ +——————-+ | Weather Forecast | | Solar Production | | Electricity Prices| | Battery Status | | | | Home Consumption | +——————-+ +——————-+

┼─────────────────────┼

│ Rest/API ▼

OpenHEMS

House Model Forecast Engine Optimization Scheduler

│ Rest/API ▼

Home-Assistant

│

┌────────────────┼────────────────┐ ▼ ▼ ▼

EV Charger Water Heater Dishwasher

```

## Responsibilities

OpenHEMS separates responsibilities into three distinct layers:

### Home Assistant

Home Assistant is responsible for communicating with physical devices. It exposes sensors, switches, climate entities and services.

### OpenHEMS

OpenHEMS builds an internal representation of the house using data from Home Assistant and external providers (weather, tariffs, forecasts). It computes an optimal schedule according to user-defined objectives and constraints.

### Devices

Devices simply execute the commands issued by Home Assistant. They do not contain any optimization logic.

## Decision Loop

At regular intervals, OpenHEMS performs the following steps:

  1. Read the current state of the house.

  2. Retrieve forecasts (solar production, weather, electricity prices, etc.).

  3. Build an internal model of available energy and expected consumption.

  4. Compute the optimal schedule according to the selected strategy.

  5. Send commands to Home Assistant when actions are required.

6. Wait to avoid unnecessary power consumption/requests (by default 30 secondes from step 1). 6. Repeat.

## Example

Imagine the following situation:

``` 11:30 PV forecast predicts 5 kW of solar production around noon.

↓

OpenHEMS postpones the dishwasher instead of starting it immediately.

↓

12:15 Solar production reaches the expected level.

↓

Dishwasher starts automatically.

↓

13:00 The EV charger starts.

↓

The battery remains above the configured minimum state of charge. ```

Instead of reacting to events one by one, OpenHEMS plans ahead to maximize self-consumption, reduce electricity costs, and respect the user’s preferences and system constraints.

Overview

You could insert it in Home-Assistant like this.

![Screenshot](docs/images/dashboard_openhems.png)

And here we ask the “voiture” to start for 2 hours (Here configured in french).

![Screenshot configured](docs/images/dashboard_openhems_filled.png)

Features

white_check_mark:

Home-Assistant integration

white_check_mark:

Easy installation and UI configuration with HTML pages

white_check_mark:

Support multiple off-peak time-slots and even variable time-slots and cost (RTE Tempo contract).

white_check_mark:

Usefull if you don’t have solar panel but only a contract with off-peak.

white_check_mark:

Support solar panel management with EMHASS using AI

white_check_mark:

Support basic solar panel management without AI for no sell or no buy strategy.

white_check_mark:

Home-Assistant widget to schedule devices (washing-machine, charging car… )

white_check_mark:

Time-out for scheduled devices (to force run even if not good to get ready on time).

white_check_mark:

Set the appliance to run automatically until X

white_check_mark:

Set priority handling between multiple appliances

white_check_mark:

Always check maximum capacities to avoid black-out

We are expected to add soon the following features. We need beta-tester for those features. If you are interested, please contact us.

x:

Variable switch support (like solar router, wall-box)

x:

Works with hybrid and standard inverters

x:

Domoticz integration (a embryo exist)

x:

Jeedom integration

x:

Dynamic tariffs (a draft exist)

x:

Vehicle-to-grid

x:

Heat pumps

x:

Learning strategy

What OpenHEMS is not.

warning:

It will never guarantee a reaction time due to the performance of the home automation network and OpenHEMS (the worst is WiFi).

warning:

Due to the licence, we do not garentee there is no bugs or problems. For garentee like this please contact us for a comercial support.

Prerequisites

  • Controlable devices:

    • devices witch start on plug like electric-car or old washing machine.

    • connected devices like washing-machine.

  • Advantages to delay some consumption. Depending on your electric source (Contract with offpeak hours, solar panels).

  • A Linux based server, connected to home network, with a recent Python installation.

  • And some software skills…

  • More prerequisites, for installation are detailed on installation’s documentation.

Install this software

It is integrate to Home-Assistant as an add-on on HAOS. Please in addon-modules add a store url “https://github.com/abriotde/openhems-addon”. Then refresh the store annd click to add OpenHEMS.

Once install, you have to configure it. Open the “web interface” and choice “parameters” in the menu. There is a video, in French, to explain how to install and configure OpenHEMS on [Youtube](https://www.youtube.com/watch?v=1rb9n-XyTsM). You can to read the documentation (RTFM) the [documentation](https://openhems.readthedocs.io/en/latest/installation.html) or see example in config/openhems.yaml or tests/data/*.yaml or src/openhems/data/openhems_default.yaml. Please contact us if you have problems.

Once configured, you will add a tile in your Home-Asssitant dashboard. Add a web-page tile. To know the url, open the “web interface” of OpenHEMS and copy the URL and add “/?n=1” at end. You will obtain something like “http://192.168.1.202:8000/?n=1”. You should just change “192.168.1.202” part.

Additional documentation