Add using join

[
    {
        "id": "8223cd267ed3d677",
        "type": "inject",
        "z": "5c6912249ebb28e5",
        "name": "power-meter 5A",
        "props": [
            {
                "p": "payload.power_meter_current",
                "v": "5.0",
                "vt": "num"
            },
            {
                "p": "topic",
                "vt": "str"
            }
        ],
        "repeat": "",
        "crontab": "",
        "once": false,
        "onceDelay": 0.1,
        "topic": "power-meter",
        "x": 180,
        "y": 1020,
        "wires": [
            [
                "b1ceb258b65a4f51"
            ]
        ]
    },
    {
        "id": "48b69b30cf747fd2",
        "type": "inject",
        "z": "5c6912249ebb28e5",
        "name": "inverter 3.5A",
        "props": [
            {
                "p": "payload.inverter_current",
                "v": "3.5",
                "vt": "num"
            },
            {
                "p": "topic",
                "vt": "str"
            }
        ],
        "repeat": "",
        "crontab": "",
        "once": false,
        "onceDelay": 0.1,
        "topic": "inverter",
        "x": 170,
        "y": 1160,
        "wires": [
            [
                "b1ceb258b65a4f51"
            ]
        ]
    },
    {
        "id": "b1ceb258b65a4f51",
        "type": "join",
        "z": "5c6912249ebb28e5",
        "name": "",
        "mode": "custom",
        "build": "merged",
        "property": "payload",
        "propertyType": "msg",
        "key": "topic",
        "joiner": "\\n",
        "joinerType": "str",
        "accumulate": true,
        "timeout": "",
        "count": "2",
        "reduceRight": false,
        "reduceExp": "",
        "reduceInit": "",
        "reduceInitType": "",
        "reduceFixup": "",
        "x": 490,
        "y": 1120,
        "wires": [
            [
                "a67ade2e6367507d",
                "fbde6e0b5dde3eb5"
            ]
        ]
    },
    {
        "id": "893f088db85ef46d",
        "type": "debug",
        "z": "5c6912249ebb28e5",
        "name": "debug 21",
        "active": true,
        "tosidebar": true,
        "console": false,
        "tostatus": false,
        "complete": "false",
        "statusVal": "",
        "statusType": "auto",
        "x": 860,
        "y": 1120,
        "wires": []
    },
    {
        "id": "a67ade2e6367507d",
        "type": "function",
        "z": "5c6912249ebb28e5",
        "name": "function 1",
        "func": "msg.payload.total = msg.payload.power_meter_current + msg.payload.inverter_current;\nreturn msg;",
        "outputs": 1,
        "noerr": 0,
        "initialize": "",
        "finalize": "",
        "libs": [],
        "x": 640,
        "y": 1120,
        "wires": [
            [
                "893f088db85ef46d"
            ]
        ]
    },
    {
        "id": "8f5feff7cca56a63",
        "type": "inject",
        "z": "5c6912249ebb28e5",
        "name": "power-meter 13A",
        "props": [
            {
                "p": "payload.power_meter_current",
                "v": "13.0",
                "vt": "num"
            },
            {
                "p": "topic",
                "vt": "str"
            }
        ],
        "repeat": "",
        "crontab": "",
        "once": false,
        "onceDelay": 0.1,
        "topic": "power-meter",
        "x": 180,
        "y": 1060,
        "wires": [
            [
                "b1ceb258b65a4f51"
            ]
        ]
    },
    {
        "id": "c8ebf6249146feec",
        "type": "inject",
        "z": "5c6912249ebb28e5",
        "name": "inverter 8A",
        "props": [
            {
                "p": "payload.inverter_current",
                "v": "8.0",
                "vt": "num"
            },
            {
                "p": "topic",
                "vt": "str"
            }
        ],
        "repeat": "",
        "crontab": "",
        "once": false,
        "onceDelay": 0.1,
        "topic": "inverter",
        "x": 160,
        "y": 1200,
        "wires": [
            [
                "b1ceb258b65a4f51"
            ]
        ]
    },
    {
        "id": "fbde6e0b5dde3eb5",
        "type": "debug",
        "z": "5c6912249ebb28e5",
        "name": "debug 22",
        "active": false,
        "tosidebar": true,
        "console": false,
        "tostatus": false,
        "complete": "false",
        "statusVal": "",
        "statusType": "auto",
        "x": 640,
        "y": 1180,
        "wires": []
    },
    {
        "id": "379ebd1c47e87078",
        "type": "comment",
        "z": "5c6912249ebb28e5",
        "name": "Simulate Power meter topic",
        "info": "",
        "x": 200,
        "y": 980,
        "wires": []
    },
    {
        "id": "f042deab96497ff5",
        "type": "comment",
        "z": "5c6912249ebb28e5",
        "name": "Simulate Inverter topic",
        "info": "",
        "x": 180,
        "y": 1120,
        "wires": []
    }
]