This file shows how to consume a SOLR API in your PHP script as a JSON output. The script is easy and less than half a dozen code lines. You can find example and tutorial at SOLR Search in PHP tutorial.

SOLR-PHP-JSON-API.php

<?php

//replace with your query URL
$url = "http://127.0.0.1:8080/solr/core1/select/?q=*%3A*&start=0&rows=10&wt=json";

//Executes the URL and saves the content (json) in the variable.
$content = file_get_contents($url);
if($content) {
  $result = json_decode($content,true);

	//prints the content of array on the page. Instead perform the operation you ae interested.
	var_dump($result);
}
?>

The tutorial about how to use PHP to connect and search in SOLR can be found at SOLR-PHP Search Tutorial.