<?php
$data = 
            array(
                array('time' => '2014-12-01T00:00:00', 'value' => 0.0107),
                array('time' => '2014-12-01T00:05:35', 'value' => 0.0321),
                array('time' => '2014-12-01T00:05:35', 'value' => 0.0107),
                array('time' => '2014-12-01T00:06:41', 'value' => 0.0119),
                array('time' => '2014-12-01T00:06:41', 'value' => 0.0109),
                array('time' => '2014-12-01T00:06:41', 'value' => 0.0108),
                array('time' => '2014-12-01T00:06:41', 'value' => 0.0109),
                array('time' => '2014-12-01T00:06:41', 'value' => 0.0108),
                array('time' => '2014-12-02T00:06:41', 'value' => 0.0108)
            );

        $sortedData = array();
        $index = 0;
        foreach ($data as $element) {
            $timestamp = strtotime($element['time']);
            $date = date("d.m.Y", $timestamp); 
            if ( ! isset($sortedData[$date][$element['time']]) ) { 
                $sortedData[$date][$element['time']] = $element;
$sortedData[$date][$element['time']]['lowest_value'] = $element['value'];
            }
                if ($sortedData[$date][$element['time']]['lowest_value'] >  $element['value']) {
                    $sortedData[$date][$element['time']] = $element;
                    $sortedData[$date][$element['time']]['lowest_value'] =  $element['value'];
                }
        }

var_dump($sortedData);