I’m using Home Assistant in a VM and the main branch of the Zigbee2MQTT add-on (currently 1.28.0-1). To make the above linked updated file work properly in that setup, I had to adjust the require statement paths slightly by replacing the ../ with zigbee-herdsman-convertors/ like so:
const fz = require('zigbee-herdsman-converters/converters/fromZigbee');
const tz = require('zigbee-herdsman-converters/converters/toZigbee');
const exposes = require('zigbee-herdsman-converters/lib/exposes');
const globalStore = require('zigbee-herdsman-converters/lib/store');
const reporting = require('zigbee-herdsman-converters/lib/reporting');
const ota = require('zigbee-herdsman-converters/lib/ota');
const utils = require('zigbee-herdsman-converters/lib/utils');
Once done I’m getting power readings in Zigbee2MQTT now. 
My exact steps:
- Save the
inovelli.jsfile locally and modify the require statements per above. - Using the File Editor in Home Assistant, upload it to the
config/zigbee2mqttfolder. - Edit
config/zigbee2mqtt/configuration.yamland add a line like so:
external_converters:
- inovelli.js
- Restart zigbee2mqtt and you should have the power readings.