diff --git a/composer.json b/composer.json
index fd3e72f..29ce682 100644
--- a/composer.json
+++ b/composer.json
@@ -1,47 +1,46 @@
 {
-  "name": "atk4/chart",
-  "type": "library",
-  "description": "ChartJS for Agile UI",
-  "keywords": [
-    "agile",
-    "data",
-    "framework",
-    "chart",
-    "chartjs"
-  ],
-  "homepage": "https://github.com/atk4/chart",
-  "license": "MIT",
-  "authors": [
-    {
-      "name": "Romans Malinovskis",
-      "email": "romans@agiletoolkit.org",
-      "homepage": "https://nearly.guru/"
-    }
-  ],
-  "minimum-stability": "dev",
-  "prefer-stable": true,
-  "config": {
-    "sort-packages": true
-  },
-  "require": {
-    "atk4/ui": "dev-develop"
-  },
-  "require-release": {
-    "atk4/ui": "~2.3.0"
-  },
-  "require-dev": {
-    "friendsofphp/php-cs-fixer": "^2.16",
-    "phpunit/phpcov": "*",
-    "phpunit/phpunit": "*"
-  },
-  "autoload": {
-    "psr-4": {
-      "Atk4\\Chart\\": "src/"
-    }
-  },
-  "autoload-dev": {
-    "psr-4": {
-      "Atk4\\Chart\\Tests\\": "tests/"
-    }
-  }
-}
+	"name" : "atk4/chart",
+	"type" : "library",
+	"description" : "ChartJS for Agile UI",
+	"keywords" : [
+		"agile",
+		"data",
+		"framework",
+		"chart",
+		"chartjs"
+	],
+	"homepage" : "https://github.com/atk4/chart",
+	"license" : "MIT",
+	"authors" : [{
+			"name" : "Romans Malinovskis",
+			"email" : "romans@agiletoolkit.org",
+			"homepage" : "https://nearly.guru/"
+		}
+	],
+	"minimum-stability" : "dev",
+	"prefer-stable" : true,
+	"config" : {
+		"sort-packages" : true
+	},
+	"require" : {
+		"atk4/ui" : "dev-develop"
+	},
+	"require-release" : {
+		"atk4/ui" : "~2.3.0"
+	},
+	"require-dev" : {
+		"friendsofphp/php-cs-fixer" : "^2.16",
+		"phpunit/phpcov" : "*",
+		"phpunit/phpunit" : "*"
+	},
+	"autoload" : {
+		"psr-4" : {
+			"Atk4\\Chart\\" : "src/"
+		}
+	},
+	"autoload-dev" : {
+		"psr-4" : {
+			"Atk4\\Chart\\Tests\\" : "tests/"
+		}
+	}
+}
\ No newline at end of file
diff --git a/demo/index.php b/demo/index.php
index ea22262..f23c116 100644
--- a/demo/index.php
+++ b/demo/index.php
@@ -13,14 +13,16 @@
 use Atk4\Ui\Columns;
 use Atk4\Ui\Layout;
 
-$p = ['t' => [
-    ['name' => 'January', 'sales' => 20000, 'purchases' => 10000],
-    ['name' => 'February', 'sales' => 23000, 'purchases' => 12000],
-    ['name' => 'March', 'sales' => 16000, 'purchases' => 11000],
-    ['name' => 'April', 'sales' => 14000, 'purchases' => 13000],
-]];
-$m = new Model(new Array_($p), 't');
+$t = [ 
+    1 => ['name' => 'January', 'sales' => 20000, 'purchases' => 10000],
+    2 => ['id' => 2, 'name' => 'February', 'sales' => 23000, 'purchases' => 12000],
+    3 => ['id' => 3,'name' => 'March', 'sales' => 16000, 'purchases' => 11000],
+    4 => ['id' => 4,'name' => 'April', 'sales' => 14000, 'purchases' => 13000]];
+
+$m = new \Atk4\Data\Model(new \Atk4\Data\Persistence\Array_($t));
+
 $m->addFields(['name', 'sales', 'purchases', 'profit']);
+
 $m->onHook($m::HOOK_AFTER_LOAD, function ($m) { $m->set('profit', $m->get('sales') - $m->get('purchases')); });
 $app = new App('Chart Demo');
 $app->initLayout([Layout\Centered::class]);
diff --git a/src/Chart.php b/src/Chart.php
index 84d5403..4fa5a83 100644
--- a/src/Chart.php
+++ b/src/Chart.php
@@ -31,10 +31,14 @@ class Chart extends View
         ['rgba(75, 192, 192, 0.2)', 'rgba(75, 192, 192, 1)'],
         ['rgba(153, 102, 255, 0.2)', 'rgba(153, 102, 255, 1)'],
         ['rgba(255, 159, 64, 0.2)', 'rgba(255, 159, 64, 1)'],
+        ['rgba(20, 20, 20, 0.2)', 'rgba(20, 20, 20, 1)']
     ];
 
     /** @var array Options for chart.js widget */
     public $options = [];
+    
+    /** @var array Set stack id for each column, leave empty if no stacks */
+    public $stacks = [];
 
     /** @var array Labels for axis. Fills with setModel(). */
     protected $labels;
@@ -123,14 +127,20 @@ public function setOptions(array $options)
      *
      * This component will automatically figure out name of the chart,
      * series titles based on column captions etc.
+     * 
+     * Example for bar chart with two side-by side bars per category, and one of them stacked:
+     * 
+     * $chart->setModel($model, ['month', 'turnover_month_shoes', 'turnover_month_shirts', 'turnover_month_trousers', 'turnover_month_total_last_year'], [0,0,0,1]);
+     * 
      */
-    public function setModel(Model $model, array $columns = []): Model
+    public function setModel(Model $model, array $columns = [], array $stacks = []): void
     {
         if (!$columns) {
             throw new Exception('Second argument must be specified to Chart::setModel()');
         }
 
         $this->dataSets = [];
+        $this->stacks = $stacks;
 
         // Initialize data-sets
         foreach ($columns as $key => $column) {
@@ -141,14 +151,20 @@ public function setModel(Model $model, array $columns = []): Model
             }
 
             $colors = array_shift($this->nice_colors);
+            $stack = array_shift($this->stacks);
 
             $this->dataSets[$column] = [
                 'label' => $model->getField($column)->getCaption(),
                 'backgroundColor' => $colors[0],
                 'borderColor' => $colors[1],
                 'borderWidth' => 1,
+                'stack' => $stack,
                 'data' => [],
             ];
+            
+            if ($stacks != []) {
+                $this->setOptions(['scales' => ['yAxes' => [0 => ['stacked' => true]], 'xAxes' => [0 => ['stacked' => true]]]]);
+            }
         }
 
         // Prepopulate data-sets
@@ -159,7 +175,6 @@ public function setModel(Model $model, array $columns = []): Model
             }
         }
 
-        return $model;
     }
 
     /**
diff --git a/src/PieChart.php b/src/PieChart.php
index f1f309a..db7972d 100644
--- a/src/PieChart.php
+++ b/src/PieChart.php
@@ -21,7 +21,7 @@ class PieChart extends Chart
      * This component will automatically figure out name of the chart,
      * series titles based on column captions etc.
      */
-    public function setModel(Model $model, array $columns = []): Model
+    public function setModel(Model $model, array $columns = []): void
     {
         if (!$columns) {
             throw new Exception('Second argument must be specified to Chart::setModel()');
@@ -60,7 +60,6 @@ public function setModel(Model $model, array $columns = []): Model
             }
         }
 
-        return $model;
     }
 
     /**