Laravel avoid running out of memory

Im trying to use laravel excel to create an excel sheet. Because my database is expanding the memory limit is reached and I get the error:

FatalErrorException in Connection.php line 321: Allowed memory size of 134217728 bytes exhausted (tried to allocate 196605 bytes)

I already raised the memory limit a few times but I would like to improve the function so it uses less memory so I dont need to raise the memory limit everytime. I already use chuncking to try and lower the memory using but to no avail.

My function:

public function exportExcel($year)
{

    $datum = date("d-m-Y");


    Excel::create('Sales export '.$datum, function($excel)use($year) {


        $datum = date("d-m-Y");

        // Chain the setters
        $excel->setCreator('author name')
            ->setCompany('company name')
            ->setDescription('sales export.')
            ->setTitle('sales export '.$datum);

        $excel->sheet('sales '.$datum, function($sheet)use ($year) {

            $sheet->appendRow(array(
                "merk","product","artikel nr","afbeelding","categorie","collectie","maat","omschrijving","inkoopprijs","verkoopprijs","prijs betaald","aantal verkocht","verkocht aan",  "totaal","dag","maand","jaar","kwartaal","reseller","verkoper","bestel naam", "status"
            ));
            Order::whereYear('created_at', '=', $year)->orderBy('billed_at','desc')->chunk(1, function($orders)use ($sheet){
                foreach($orders as $index => $order)
                {

                    foreach($order->products as $p)
                    {

                        $sizeLink = $p->productSize;
                        $productLink = $sizeLink->product;


                        // Append row as very last
                        $sheet->appendRow(array(
                            //Merknaam  Artikelnr.  Soort   Kleur   Maat
                            //Omschrijving  Geboekt aantal  Basiseenheid
                            //inkoopprijs   verkoopprijs    aant stuks verkocht
                            //Maand Jaar    Kwartaal


                            $productLink->brand->name, //merknaam
                            $productLink->name, //productnaam
                            $productLink->artnr, //Artikelnr
                            //link naar de hoofdafbeelding
                            "". URL::to('/'). ucfirst($productLink->mainthumb),
                            $productLink->category->name, //soort
                            $productLink->collection->name, //soort
                            $sizeLink->size->name,   //maat naam
                            $productLink->desciption,   //omschrijving
                            number_format((float) $productLink->price_buy_in, 2, ',', ''), //inkoopprijs
                            number_format((float) $productLink->price, 2, ',', ''), //verkoopprijs
                            number_format((float) $p->price, 2, ',', ''), //prijs betaald
                            $p->quantity, //geboekt aantal
                            $order->billingname . $order->billingnamelast, //verkocht aan
                            number_format((float) $p->quantity * $p->price, 2, ',', ''), // totaal kosten
                            //number_format((float) ($p->quantity * $p->price - $p->quantity * $p->price_buy_in), 2, ',', ''), // winst inkoop-verkoop
                            date("d",strtotime($order->billed_at)), //dag
                            date("n",strtotime($order->billed_at)), //maand
                            date("Y",strtotime($order->billed_at)), //jaar
                            ceil(date("m",strtotime($order->billed_at))/3), // kwartaal
                            $order->reseller->name, // verkoper
                            $order->creator, // verkoper
                            $order->name, //text op factuur
                            $order->status->name,
                        ));
                    }
                }

            });


            // Auto filter for entire sheet
            $sheet->setAutoFilter();
            $sheet->freezeFirstRow();
            // Set black background
            $sheet->row(1, function($row) {

                // call cell manipulation methods
                $row->setBackground('#cccccc');
                $row->setFontWeight("bold");

            });
    $sheet->setColumnFormat(array(
        'G' =>  \PHPExcel_Style_NumberFormat::FORMAT_NUMBER_00,
        'H' => '[$EUR ]#,##0.00_-',
        'I' =>  \PHPExcel_Style_NumberFormat::FORMAT_NUMBER_00,
    ));

        });

    })->download('xlsx');;
}

I know I could raise the memory limit but I would like to find out why so much memory is used and how I can avoid using to much memory.

via Chebli Mohamed