Publish limits via MQTT

config.schema.json

@@ -412,6 +412,39 @@
               "description": "MQTT meter configuration"
             }
           ]
+        },
+        "publish": {
+          "type": "object",
+          "properties": {
+            "mqtt": {
+              "type": "object",
+              "properties": {
+                "host": {
+                  "type": "string",
+                  "description": "The host of the MQTT broker, including \"mqtt://\""
+                },
+                "username": {
+                  "type": "string",
+                  "description": "The username for the MQTT broker"
+                },
+                "password": {
+                  "type": "string",
+                  "description": "The password for the MQTT broker"
+                },
+                "topic": {
+                  "type": "string",
+                  "description": "The topic to publish limits"
+                }
+              },
+              "required": [
+                "host",
+                "topic"
+              ],
+              "additionalProperties": false
+            }
+          },
+          "additionalProperties": false,
+          "description": "Publish active control limits"
         }
       },
       "required": [

src/coordinator/helpers/inverterController.ts

@@ -22,6 +22,7 @@ import { CappedArrayStack } from '../../helpers/cappedArrayStack.js';
 import { timeWeightedAverage } from '../../helpers/timeWeightedAverage.js';
 import { differenceInSeconds } from 'date-fns';
 import { type ControlsModel } from '../../connections/sunspec/models/controls.js';
+import { Publish } from './publish.js';
 
 export type SupportedControlTypes = Extract<
     ControlType,
@@ -69,6 +70,7 @@ const defaultValues = {
 } as const satisfies Record<ControlType, unknown>;
 
 export class InverterController {
+    private activeLimitOutput: Publish;
     private cachedDerSample = new CappedArrayStack<DerSample>({ limit: 100 });
     private cachedSiteSample = new CappedArrayStack<SiteSample>({ limit: 100 });
     private logger: Logger;
@@ -105,6 +107,7 @@ export class InverterController {
             inverterConfiguration: InverterConfiguration,
         ) => Promise<void>;
     }) {
+        this.activeLimitOutput = new Publish({ config });
         this.secondsToSample = config.inverterControl.sampleSeconds;
         this.controlFrequencyMinimumSeconds =
             config.inverterControl.controlFrequencyMinimumSeconds;
@@ -172,6 +175,10 @@ export class InverterController {
 
         writeActiveControlLimit({ limit: activeInverterControlLimit });
 
+        this.activeLimitOutput.onActiveInverterControlLimit({
+            limit: activeInverterControlLimit,
+        });
+
         this.controlLimitsCache = {
             controlLimitsByLimiter,
             activeInverterControlLimit,

src/coordinator/helpers/publish.ts

@@ -0,0 +1,29 @@
+import mqtt from 'mqtt';
+import { type Config } from '../../helpers/config.js';
+import { type ActiveInverterControlLimit } from './inverterController.js';
+
+export class Publish {
+    private mqttClient: mqtt.MqttClient | undefined;
+
+    constructor({ config }: { config: Config }) {
+        if (config.publish?.mqtt) {
+            this.mqttClient = mqtt.connect(config.publish.mqtt.host, {
+                username: config.publish.mqtt.username,
+                password: config.publish.mqtt.password,
+            });
+        }
+    }
+
+    onActiveInverterControlLimit({
+        limit,
+    }: {
+        limit: ActiveInverterControlLimit;
+    }) {
+        if (this.mqttClient) {
+            this.mqttClient.publish(
+                'inverterControlLimit',
+                JSON.stringify(limit),
+            );
+        }
+    }
+}

src/helpers/config.ts

@@ -237,6 +237,29 @@ A longer time will smooth out load changes but may result in overshoot.`,
             })
             .describe('MQTT meter configuration'),
     ]),
+    publish: z
+        .object({
+            mqtt: z
+                .object({
+                    host: z
+                        .string()
+                        .describe(
+                            'The host of the MQTT broker, including "mqtt://"',
+                        ),
+                    username: z
+                        .string()
+                        .optional()
+                        .describe('The username for the MQTT broker'),
+                    password: z
+                        .string()
+                        .optional()
+                        .describe('The password for the MQTT broker'),
+                    topic: z.string().describe('The topic to publish limits'),
+                })
+                .optional(),
+        })
+        .describe('Publish active control limits')
+        .optional(),
 });
 
 export type Config = z.infer<typeof configSchema>;