diff --git a/src/main/java/no/halvorteigen/powerassetoptimizer/controller/AssetController.java b/src/main/java/no/halvorteigen/powerassetoptimizer/controller/AssetController.java
index 4437f63..e3e4359 100644
--- a/src/main/java/no/halvorteigen/powerassetoptimizer/controller/AssetController.java
+++ b/src/main/java/no/halvorteigen/powerassetoptimizer/controller/AssetController.java
@@ -7,9 +7,6 @@
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.*;
 
-/**
- * NOTE: The asset registers through this API
- */
 @RestController
 @RequestMapping("api/v1/asset")
 public class AssetController {
diff --git a/src/main/java/no/halvorteigen/powerassetoptimizer/controller/PowerOptimizationController.java b/src/main/java/no/halvorteigen/powerassetoptimizer/controller/PowerOptimizationController.java
index 8e10cf6..0944671 100644
--- a/src/main/java/no/halvorteigen/powerassetoptimizer/controller/PowerOptimizationController.java
+++ b/src/main/java/no/halvorteigen/powerassetoptimizer/controller/PowerOptimizationController.java
@@ -12,9 +12,6 @@
 import java.util.Map;
 import java.util.Optional;
 
-/**
- * NOTE: The asset polls its optimized power usage through this API
- */
 @RestController
 @RequestMapping("api/v1/optimize")
 public class PowerOptimizationController {
@@ -27,7 +24,6 @@ public PowerOptimizationController(AssetRepository assetRepository, PowerOptimiz
         this.powerOptimizationService = powerOptimizationService;
     }
 
-    // NOTE: Assuming that returning a Map instead of a list is ok. Can easily be converted to a list if needed.
     @GetMapping("/{assetName}")
     public ResponseEntity<Map<Integer, Double>> optimizeAssetPower(@PathVariable String assetName) {
         Optional<AssetEntity> assetOpt = assetRepository.findByName(assetName);
diff --git a/src/main/java/no/halvorteigen/powerassetoptimizer/service/PowerOptimizationService.java b/src/main/java/no/halvorteigen/powerassetoptimizer/service/PowerOptimizationService.java
index 156f45d..b190b6f 100644
--- a/src/main/java/no/halvorteigen/powerassetoptimizer/service/PowerOptimizationService.java
+++ b/src/main/java/no/halvorteigen/powerassetoptimizer/service/PowerOptimizationService.java
@@ -18,6 +18,7 @@
 
 @Service
 public class PowerOptimizationService {
+
     public static final int HOURS_PER_DAY = 24;
     private final PowerPriceService powerPriceService;
     private final Clock clock;
@@ -72,11 +73,6 @@ public Map<Integer, Double> optimizePowerUsage(AssetEntity asset) {
             GoalType.MINIMIZE
         ).getPoint();
 
-        for (int i = 0; i < solution.length; i++) {
-            System.out.println("power = " + solution[i] + ", price = " + prices[i] + ", cost = " + solution[i] * prices[i]);
-        }
-        System.out.println("Total cost = " + objectiveFunction.value(solution));
-
         return IntStream.range(0, solution.length)
                         .boxed()
                         .collect(Collectors.toMap(index -> index, index -> solution[index]));
diff --git a/src/main/java/no/halvorteigen/powerassetoptimizer/service/PowerPriceService.java b/src/main/java/no/halvorteigen/powerassetoptimizer/service/PowerPriceService.java
index 4fd3519..2e6fcad 100644
--- a/src/main/java/no/halvorteigen/powerassetoptimizer/service/PowerPriceService.java
+++ b/src/main/java/no/halvorteigen/powerassetoptimizer/service/PowerPriceService.java
@@ -4,6 +4,7 @@
 import no.halvorteigen.powerassetoptimizer.enums.PriceArea;
 import no.halvorteigen.powerassetoptimizer.mappers.MapPowerPriceDtoToPowerPrice;
 import no.halvorteigen.powerassetoptimizer.model.PowerPrice;
+import no.halvorteigen.powerassetoptimizer.utils.DateUtils;
 import no.halvorteigen.powerassetoptimizer.utils.NumberUtils;
 import org.springframework.stereotype.Service;
 import org.springframework.web.client.RestTemplate;
@@ -14,7 +15,6 @@
 @Service
 public class PowerPriceService {
 
-    // NOTE: May want to have this url as a configuration property
     public static final String BASE_URL = "https://www.hvakosterstrommen.no/api/v1/prices/";
     private final RestTemplate restTemplate;
 
@@ -34,7 +34,10 @@ public List<PowerPrice> getPowerPrices(int year, int month, int day, PriceArea p
     }
 
     private static String getUrl(int year, int month, int day, PriceArea priceArea) {
-        // NOTE: Assuming year, month and day are valid
+        boolean isValidDate = DateUtils.isValidDate(year, month, day);
+        if (!isValidDate) {
+            throw new IllegalArgumentException("Invalid day, month or year.");
+        }
         String monthFormatted = NumberUtils.fillLeadingZeros(month, 2);
         String dayFormatted = NumberUtils.fillLeadingZeros(day, 2);
         return BASE_URL + year + "/" + monthFormatted + "-" + dayFormatted + "_" + priceArea.name() + ".json";
diff --git a/src/main/java/no/halvorteigen/powerassetoptimizer/utils/DateUtils.java b/src/main/java/no/halvorteigen/powerassetoptimizer/utils/DateUtils.java
new file mode 100644
index 0000000..51326bc
--- /dev/null
+++ b/src/main/java/no/halvorteigen/powerassetoptimizer/utils/DateUtils.java
@@ -0,0 +1,19 @@
+package no.halvorteigen.powerassetoptimizer.utils;
+
+import java.time.DateTimeException;
+import java.time.YearMonth;
+
+public class DateUtils {
+
+    private DateUtils() {
+        // Hide default constructor
+    }
+
+    public static boolean isValidDate(int year, int month, int day) {
+        try {
+            return YearMonth.of(year, month).isValidDay(day);
+        } catch (DateTimeException exception) {
+            return false;
+        }
+    }
+}
diff --git a/src/test/java/no/halvorteigen/powerassetoptimizer/service/PowerOptimizationServiceTest.java b/src/test/java/no/halvorteigen/powerassetoptimizer/service/PowerOptimizationServiceTest.java
index 075050d..4992f9f 100644
--- a/src/test/java/no/halvorteigen/powerassetoptimizer/service/PowerOptimizationServiceTest.java
+++ b/src/test/java/no/halvorteigen/powerassetoptimizer/service/PowerOptimizationServiceTest.java
@@ -22,9 +22,6 @@
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
-/**
- * NOTE: The tests do not use realistic numbers, just random numbers that cause the desired behavior
- */
 @ExtendWith(MockitoExtension.class)
 class PowerOptimizationServiceTest {
 
@@ -58,10 +55,10 @@ void should_optimize_power() {
             .limit(24)
             .toArray(PowerPriceDto[]::new);
         Mockito.when(restTemplate.getForObject(
-                   ArgumentMatchers.anyString(),
-                   ArgumentMatchers.eq(PowerPriceDto[].class)
-               ))
-               .thenReturn(powerPriceDtos);
+                ArgumentMatchers.anyString(),
+                ArgumentMatchers.eq(PowerPriceDto[].class)
+            ))
+            .thenReturn(powerPriceDtos);
 
         PowerOptimizationService powerOptimizationService = new PowerOptimizationService(
             powerPriceService,
@@ -108,10 +105,10 @@ void should_throw_exception_when_infeasible_optimization_problem() {
             .limit(24)
             .toArray(PowerPriceDto[]::new);
         Mockito.when(restTemplate.getForObject(
-                   ArgumentMatchers.anyString(),
-                   ArgumentMatchers.eq(PowerPriceDto[].class)
-               ))
-               .thenReturn(powerPriceDtos);
+                ArgumentMatchers.anyString(),
+                ArgumentMatchers.eq(PowerPriceDto[].class)
+            ))
+            .thenReturn(powerPriceDtos);
 
         PowerOptimizationService powerOptimizationService = new PowerOptimizationService(
             powerPriceService,