node_helper.js

const NodeHelper = require("node_helper");
const Growatt = require("growatt");
const fetch = require("node-fetch");

const options = {
    plantData: true,
    weather: false,
    totalData: false,
    statusData: true,
    deviceData: true,
    deviceType: false,
    historyLast: true,
    historyAll: false,
};

module.exports = NodeHelper.create({
    requiresVersion: "2.21.0",

    start: function () {
        console.log("Starting node helper for " + this.name);
    },

    stop: async function() {
        if(this.growatt) {
            const logout = await this.growatt.logout().catch((e) => {
                console.log(e);
            });
            console.log("logout:", logout);
        }
    },

    calcSpeed: function(watt) {
        const MAX_WATT = 10000;
        // 0.25 - 4.25s (peak at 10 000 W)
        const exponentialWatt = Math.pow(Math.min(Math.abs(watt), MAX_WATT), 2);
        const seconds = 4.25 - Math.min(exponentialWatt / 25000000, 4);
        return `${seconds}s`;
    },

    convertGrowattData: function (data, { plantId, deviceSerial }) {
        const production = Math.round(data[plantId].devices[deviceSerial].deviceData.pac);
        const consumption = Math.round(
            data[plantId].devices[deviceSerial].historyLast.pacToLocalLoad
        );
        const grid = consumption - production;

        const speed = {
            production: this.calcSpeed(production),
            consumption: this.calcSpeed(consumption),
            grid: this.calcSpeed(grid),
        };

        return {
            production,
            consumption,
            grid, // negative = feeding back to grid
            speed,
        };
    },

    getConnection: async function (payload) {
        if(this.growatt && this.growatt.isConnected()) {
            console.log("Found existing connection, reusing");
            return this.growatt;
        }

        console.log("Trying to connect to Growatt.")
        try {
            const growatt = new Growatt({});
            const login = await growatt.login(payload.username, payload.password)
            this.growatt = growatt;
            console.log("login:", login);
        } catch(e) {
            console.log("Error", e);
        }

        return this.growatt;
    },

    getGrowattData: async function (payload) {
        const growatt = await this.getConnection(payload);

        if(!growatt) {
            console.log("No connection, will not fetch.")
            return null;
        }

        const data = await growatt.getAllPlantData(options).catch((e) => {
            console.log(e);
        });

        const growattData = this.convertGrowattData(data, payload);
        //console.log({ growattData });

        this.sendSocketNotification("GROWATT_DATA", growattData);
    },

    getElectricityPrice: async function (payload) {
        const year = new Date().toISOString().slice(0, 4);
        const monthAndDay = new Date().toISOString().slice(5, 10);

        const res = await fetch(`https://www.elprisetjustnu.se/api/v1/prices/${year}/${monthAndDay}_${payload.area}.json`);
        const data = await res.json();
        const electricityPrice = data[new Date().getHours()].SEK_per_kWh;
        //console.log({ electricityPrice });
        this.sendSocketNotification("ELECTRICITY_PRICE", { electricityPrice });
    },

    socketNotificationReceived: function (notification, payload) {
        if (notification === "GET_GROWATT_DATA") {
            this.getGrowattData(payload);
        } else if (notification === "GET_ELECTRICITY_PRICE") {
            this.getElectricityPrice(payload);
        }
    },
});