diff --git a/src/main/angular/src/app/app.component.ts b/src/main/angular/src/app/app.component.ts
index 5dcd749..f376622 100644
--- a/src/main/angular/src/app/app.component.ts
+++ b/src/main/angular/src/app/app.component.ts
@@ -42,7 +42,7 @@ export class AppComponent implements OnInit, OnDestroy {
   }
 
   get powerSelf(): Value | undefined {
-    return this.powerProduction?.minus(this.powerDelivery);
+    return this.powerProduction?.minus(this.powerDelivery)?.notNegative();
   }
 
   get powerConsumption(): Value | undefined {