I’d like to get the value (v) of Power in the AC section of this JSON file with a PHP script.

{
"inverters": [
    {
        "serial": "xxxxxxxxxxx",
        "name": "Block1",
        "order": 0,
        "data_age": 2,
        "poll_enabled": true,
        "reachable": true,
        "producing": true,
        "AC": {
            "0": {
                "Power": {
                    "v": 666.2000122,
                    "u": "W",
                    "d": 1
                },
                "Voltage": {
                    "v": 240.1000061,
                    "u": "V",
                    "d": 1
                },
                "Current": {
                    "v": 2.769999981,
                    "u": "A",
                    "d": 2
                },
                "Frequency": {
                    "v": 50,
                    "u": "Hz",
                    "d": 2
                },
                "PowerFactor": {
                    "v": 0.949999988,
                    "u": "",
                    "d": 3
                },
                "ReactivePower": {
                    "v": 218.3999939,
                    "u": "var",
                    "d": 1
                }
            }
        }, [...]

I was trying it with the following code that worked with a simpler structure but now fails:

$PowerV = round($jsonobj->inverters[0]->AC[0]->Power->v, 2, PHP_ROUND_HALF_UP);

then I asked the copilot and it came up the the following (working) alternative:

$PowerV = round($jsonobj['inverters'][0]['AC'][0]['Power']['v'], 2, PHP_ROUND_HALF_UP);

But I still like to understand what was wrong with the original code I tried.

Thanks for your help!