# Overview

> How the Voltmasters EMS keeps a site powered during a grid outage, with the battery, a generator and a controlled return to the grid.

Source: https://voltmasters.io/en/docs/microgrid/

With **Microgrid**, the Voltmasters EMS keeps a site powered when the public grid fails. The controller separates the site from the grid, the battery forms a local grid of its own (**island operation**) and, when needed, a generator takes over. When the grid comes back, the controller reconnects the site safely and in a controlled way.

## What the customer gains

-   **Continuity**: the business keeps running during a grid outage, without anyone on site.
-   **Critical loads stay powered**: the customer chooses what may never be switched off (cold storage, servers, process). The rest is shed in order of priority.
-   **The generator only when it is needed**: it starts when the battery runs low, not at every outage. Fewer running hours, less fuel.
-   **A battery that earns its keep in normal times**: on the grid the battery keeps optimising energy costs. It only holds back a reserve for a possible outage.
-   **Everything is visible**: live status, notifications and a report on grid availability and generator use.

## How it works

1. **On the grid: the battery stands ready**
   
   The site runs normally. The controller keeps an **island reserve** in the battery (50 % by default), so there is always energy available when an outage hits.
2. **The grid fails: the site switches to island operation**
   
   The controller opens the grid breaker and the battery forms the site's grid. The switchover causes a **short interruption**, after which the site runs on its own on the battery and the solar panels. If consumption exceeds what the battery can deliver, the controller sheds the non-critical loads in the chosen order.
3. **The battery runs low: the generator starts**
   
   Below a state of charge threshold (20 % by default), the controller starts the generator. The generator then forms the grid, powers the site and recharges the battery. Above the stop threshold (90 % by default), the generator stops again.
4. **The grid returns: controlled reconnection**
   
   The controller waits until the grid voltage and frequency are stable, then reports that **the grid is back**. Reconnecting causes a short interruption (at most two minutes when the battery forms the grid). That is why a responsible person releases it with one click, at a suitable moment, in the platform or the mobile app. The site can also reconnect automatically.

A complete outage in seven steps. Watch who forms the grid: blue for the grid, green for the battery, pink for the generator.

![Voltmasters EMS, single line diagram of the microgrid. On the grid: the battery stands ready](https://voltmasters.io/assets/docs/microgrid-outage-1.webp)

*On the grid: the battery stands ready*

![Voltmasters EMS, single line diagram of the microgrid. The grid fails: the battery forms the island](https://voltmasters.io/assets/docs/microgrid-outage-2.webp)

*The grid fails: the battery forms the island*

![Voltmasters EMS, single line diagram of the microgrid. Island operation on the battery](https://voltmasters.io/assets/docs/microgrid-outage-3.webp)

*Island operation on the battery*

![Voltmasters EMS, single line diagram of the microgrid. Battery low: the generator starts](https://voltmasters.io/assets/docs/microgrid-outage-4.webp)

*Battery low: the generator starts*

![Voltmasters EMS, single line diagram of the microgrid. The generator forms the grid and charges the battery](https://voltmasters.io/assets/docs/microgrid-outage-5.webp)

*The generator forms the grid and charges the battery*

![Voltmasters EMS, single line diagram of the microgrid. The grid is back: waiting for release](https://voltmasters.io/assets/docs/microgrid-outage-6.webp)

*The grid is back: waiting for release*

![Voltmasters EMS, single line diagram of the microgrid. Reconnected: back on the grid](https://voltmasters.io/assets/docs/microgrid-outage-7.webp)

*Reconnected: back on the grid*

## What the customer sees

-   **A live single line diagram** on the project dashboard: who forms the grid, the breaker positions, the power flows and the current step of every procedure.
-   **Notifications** when the grid fails and when it returns, with the **Release reconnection** button in the platform and a push notification in the mobile app.
-   **The microgrid report**: grid availability, outages, reconnections, generator running hours and energy, fuel cost, with a CSV export.

## What the site needs

| Component | Role |
| --- | --- |
| Voltmasters controller | Runs the whole sequence: outage detection, island operation, generator, load shedding and reconnection. |
| Battery with a grid-forming inverter | Forms the site's grid during island operation. |
| Grid breaker with position feedback, and a decoupling relay | Separates the site from the public grid and confirms its position to the controller. |
| IO module (Moxa ioLogik E1214) | Connects the breakers, the protection relay and the generator start to the controller. |
| Generator (optional, DEIF AGC 150) | Takes over when the battery runs low during a long outage. |
| Solar panels (optional) | Keep producing during island operation, limited to what the site can absorb. |

## How this section is organized

-   [How Microgrid works](https://voltmasters.io/en/docs/microgrid/how-it-works/): the operating modes and every transition between them.
-   [Live monitoring](https://voltmasters.io/en/docs/microgrid/live-monitoring/): the single line diagram and the procedure panel on the dashboard.
-   [Grid reconnection](https://voltmasters.io/en/docs/microgrid/grid-reconnection/): releasing the return to the grid, step by step.
-   [Configuration](https://voltmasters.io/en/docs/microgrid/configuration/): prerequisites, microgrid settings, IO roles, generator and load shedding.
-   [Microgrid report](https://voltmasters.io/en/docs/microgrid/microgrid-report/): outages, reconnections and generator use over a period.
-   [Incidents](https://voltmasters.io/en/docs/microgrid/incidents/): the notifications Microgrid raises.

> **Note**
>
> Microgrid is enabled per project, after Voltmasters has validated the installation.