Raspberry Pi Backup Generator Monitoring

Generac Generator Monitoring over WiFi using a Raspberry Pi

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This project will monitor a backup generator that utilizes the Generac Evolution or Nexus Controllers over a WiFi or wired connection. Generac, Eaton, Honeywell and Siemens Home Backup Generators use these Generac controllers. Honeywell and Eaton call the controllers Sync 1.0 (Nexus) and Sync 2.0 (Evolution) in their documentation however all of these companies sell generators that use the controllers supported by this project. The project is written mostly in python and has been tested with a Raspberry Pi 3. Ideally you would need to create a physical enclosure for your raspberry pi and possibly make a cable to connect the raspberry pi to the Evolution or Nexus controller. If you are comfortable doing these things and you have a backup generator that has an Generac Evolution or Nexus controller then this project may be of interest to you.

See project wiki:

## Functionality

The software supports the following features:

Monitoring of the generator to to detect and report the following:

- Maintenance, Start / Stop and Alarm Logs (Nexus only supports Start / Stop Log)

- Display Generator Serial Number

- Generator warnings and faults (Wiring Error, High Temp on air cooled models, Low Oil Pressure,

low coolant on liquid cooled models)

- Generator Status:

- Engine State

- Generator Switch State (Auto, On, Off)

- Generator Engine State (Stopped, Starting, Exercising, Running Manual,

Running Utility Loss, Stopped due to Alarm, Cooling Down)

- Battery Voltage and Charging Status

- Relay Output State: (Starter, Fuel Relay, Battery Charger, others for liquid cooled models)

- Engine RPM, Hz and Voltage Output

- Generator Controller Time

- Line State

- Utility Voltage Level

- Transfer Switch State

- Outage Information

- Time since last outage

- Current Utility Voltage

- Min and Max Utility Voltage since program started

- Maintenance Information

- Weekly Exercise time, day and duration

- Hours till next scheduled service

- Total Run Hours

- Firmware and Hardware versions

- Various statics from the generator monitor including time since program launched,

MODBUS / serial communications health and program health.

Email notification of :

- Engine state change

- Switch state change

- Critical or Warning messages from the generator

Web based application for viewing status of the generator

Command Line application (all the functionality of email commands)

Ability to set exercise time

Ability to set generator time

Ability to start, stop, exercise and start / active the transfer switch

(i.e. power your house off the generator) remotely.

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View all instructions

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Ron wrote 05/09/2020 at 12:30 point

I wrote a brief addition to the WIKI to explain how to install free LetsEncrypt certificates into GENMON so chrome and other browsers stop griping about the self-signed certificate.

Alas github doesn't handle forks for the wiki like it does the sources.   Here's the link into my fork

I'm thinking of fixing the genmon code itself to handle the "webroot" authentication so that the update of the certifciate can be automatic.

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Ron wrote 03/08/2019 at 22:45 point

I have an 80KVA Generac with an H-100 controller.   It looks as if the RS-232 comes out on a DB 9 below the panel.   Does this sound right?   I see I have to change the modbus address in the software.

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jgyates wrote 04/08/2017 at 22:11 point

This may help:

It looks like you would need to step the voltage down to get it in a range that you could read it with a board like the pi.

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jgyates wrote 04/08/2017 at 22:00 point

I believe you would just want a voltage sensor, one for utility voltage and another for generator voltage, if you wanted to get fancy you could put on on your battery also, but if you kept it to just the two voltages then you could connect them to your transfer switch instead of your generator. Both the generator output and utility voltage both are available in your transfer switch. I would look at A to D converters that handle up to 300V since you utility line is at 240V (in the US anyway) but can swing up to around 260V.

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gnedeljkovic wrote 04/01/2017 at 14:29 point

Any way to make something like this work for an older generator? I just want to know when it turns on and off. Appreciate any help.

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jgyates wrote 04/05/2017 at 18:14 point

I guess it depends on how old of a generator we are talking about and the functionality of the generator. If it is a generac generator, the Nexus controller has been in use for many years. If there is no eternal communication method for your generator you should be able to tie into the transfer switch and monitor the utility line and the generator output. This would require some voltage sensors connected to an embedded micro and some python to read / notify. 
This company ( makes a solution that will monitor the utility line and the generator output report the results over wifi.

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gnedeljkovic wrote 04/05/2017 at 18:16 point

what kind of sensors and what python script should I look into? Thanks 

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