A php script that fetches nordpool electricity prices for today and check if the current hour is among the cheapest, I use it for water heater control

is_cheapest.php

<?php

date_default_timezone_set('Europe/Riga'); // Ensure correct time zone
$today = date('Y-m-d');
$area = 'LV';
$numhours = 2;

$url = "https://dataportal-api.nordpoolgroup.com/api/DayAheadPrices?date=$today&market=DayAhead&deliveryArea=$area&currency=EUR";
// Fetch JSON data from the API
$response = file_get_contents($url);

if ($response === false) {
    die("Failed to fetch data.");
}

$data = json_decode($response, true);

if (!isset($data['multiAreaEntries'])) {
    die("Invalid data format.");
}

$entries = $data['multiAreaEntries'];
$hourPrices = [];

// Go through each hourly entry and extract the price for the target area
foreach ($entries as $entry) {
    $start = strtotime($entry['deliveryStart']);
    $hour = (int) date('G', $start); // Extract hour in 0–23 format
    if (isset($entry['entryPerArea'][$area])) {
        $price = floatval($entry['entryPerArea'][$area]);
        $hourPrices[$hour] = $price;
    }
}

// Sort prices and get 2 lowest hours
asort($hourPrices);
$lowestHours = array_slice(array_keys($hourPrices), 0, $numhours);

// Check current hour
$currentHour = (int) date('G'); // 0–23 hour

// Output true if current hour is among the lowest
echo in_array($currentHour, $lowestHours) ? 'true' : 'false';