diff --git a/Jenkinsfile b/Jenkinsfile
index 83f4d175a2..144f746121 100644
--- a/Jenkinsfile
+++ b/Jenkinsfile
@@ -11,7 +11,7 @@
 ////////////////////////////////
 
 /* project configuration */
-String javaVersionId = 'jdk-8' // id that matches the java tool with the java version that should be used set as jenkins property
+String javaVersionId = 'jdk-17' // id that matches the java tool with the java version that should be used set as jenkins property
 
 /* git configuration */
 String projectName = 'simona' // name of the repository, is case insensitive
@@ -114,8 +114,7 @@ node {
 
         gradle('--refresh-dependencies clean spotlessCheck pmdMain pmdTest reportScoverage checkScoverage', projectName)
 
-        // due to an issue with openjdk-8 we use openjdk-11 for javadocs generation
-        sh(script: """set +x && cd $projectName""" + ''' set +x; ./gradlew javadoc -Dorg.gradle.java.home=/opt/java/openjdk''', returnStdout: true)
+        sh(script: """set +x && cd $projectName""" + ''' set +x; ./gradlew javadoc''', returnStdout: true)
       }
 
       // sonarqube analysis
@@ -158,7 +157,7 @@ node {
              */
             sh(
                 script: """set +x && cd $projectName""" +
-                ''' set +x; ./gradlew javadoc -Dorg.gradle.java.home=/opt/java/openjdk''',
+                ''' set +x; ./gradlew javadoc''',
                 returnStdout: true
                 )
 
@@ -388,7 +387,7 @@ def deployJavaDocs(String projectName, String sshCredentialsId, String gitChecko
       "git config user.name 'Johannes Hiry' && " +
       "git fetch --depth=1 origin api-docs && " +
       "git checkout api-docs && " +
-      "cd .. && ./gradlew javadoc -Dorg.gradle.java.home=/opt/java/openjdk && " +
+      "cd .. && ./gradlew javadoc && " +
       "cp -R build/docs/javadoc/* tmp-api-docs && " +
       "cd tmp-api-docs &&" +
       "git add --all && git commit -m 'updated api-docs' && git push origin api-docs:api-docs" +
diff --git a/build.gradle b/build.gradle
index 41fd7a3905..873cb34310 100644
--- a/build.gradle
+++ b/build.gradle
@@ -7,7 +7,7 @@ plugins {
   id 'signing'
   id 'maven-publish' // publish to a maven repo (local or mvn central, has to be defined)
   id 'pmd' // code check, working on source code
-  id 'com.diffplug.spotless' version '6.1.0'// code format
+  id 'com.diffplug.spotless' version '6.1.2'// code format
   id 'com.github.onslip.gradle-one-jar' version '1.0.6' // pack a self contained jar
   id "com.github.ben-manes.versions" version '0.40.0'
   id "de.undercouch.download" version "4.1.2" // downloads plugin
@@ -22,7 +22,7 @@ plugins {
 
 ext {
   //version (changing these should be considered thoroughly!)
-  javaVersion = JavaVersion.VERSION_1_8
+  javaVersion = JavaVersion.VERSION_17
 
   scalaVersion = '2.13'
   scalaBinaryVersion = '2.13.7'
@@ -92,7 +92,7 @@ dependencies {
   implementation "ch.qos.logback:logback-classic:1.2.10"
 
   /* testing */
-  testImplementation 'org.spockframework:spock-core:2.0-groovy-3.0'
+  testImplementation 'org.spockframework:spock-core:2.1-M2-groovy-3.0'
   testImplementation 'org.scalatestplus:mockito-3-4_2.13:3.2.9.0'
   implementation 'org.mockito:mockito-core:4.2.0' // mocking framework
   testImplementation "org.scalatest:scalatest_${scalaVersion}:3.2.10"
diff --git a/gradle.properties b/gradle.properties
index 437a644249..b761da57f7 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -9,7 +9,16 @@
 
 # Specifies the JVM arguments used for the daemon process.
 # The setting is particularly useful for tweaking memory settings.
-org.gradle.jvmargs=-Xmx4096m
+
+# Workaround to make spotless work with java 17 -
+# see https://github.com/diffplug/spotless/tree/main/plugin-gradle#google-java-format and
+# https://github.com/ie3-institute/simona/issues/59 for details
+org.gradle.jvmargs=-Xmx4096m \
+  --add-exports jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED \
+  --add-exports jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED \
+  --add-exports jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED \
+  --add-exports jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED \
+  --add-exports jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED
 
 # When configured, Gradle will run in incubating parallel mode.
 # This option should only be used with decoupled projects. More details, visit
diff --git a/src/test/groovy/edu/ie3/simona/model/participant/PVModelTest.groovy b/src/test/groovy/edu/ie3/simona/model/participant/PVModelTest.groovy
index 01a755c624..6cb8535c2c 100644
--- a/src/test/groovy/edu/ie3/simona/model/participant/PVModelTest.groovy
+++ b/src/test/groovy/edu/ie3/simona/model/participant/PVModelTest.groovy
@@ -317,7 +317,7 @@ class PVModelTest extends Specification {
 		where: "the following parameters are given"
 		latitudeInDeg | deltaIn | omegaIn || alphaSOut
 		43d           | -14d    | -37.5d  || 23.4529893659531784299686037109330117049955654837550  // '2011-02-13T09:30:00'
-		43d           | 23.1d   | 97.5d   || 10.3561513175064165807300181176479988436754378357928 // '2011-07-01T06:30:00'
+		43d           | 23.1d   | 97.5d   || 10.356151317506402829742934977890382350725031728508 // '2011-07-01T06:30:00'
 	}
 
 	def "Calculate Rb (cos(thetaG)/cos(thetaZ))"() {
@@ -349,8 +349,8 @@ class PVModelTest extends Specification {
 		45            | -7.15   | -82.5   | 0     | 0       || 89.795654742951077439582101317248278436936658210074  // thetaZ
 		40            | -11.6   | -82.5   | 60    | 0       || 79.110119287443572813858647674599902596082559960114
 		40            | -11.6   | 82.5    | 60    | 0       || 79.110119287443572813858647674599902596082559960114
-		40            | -11.6   | -78.0   | 60    | 0       || 74.9207206518514467357682971033566198212518156744
-		40            | -11.6   | 78.0    | 60    | 0       || 74.9207206518514467357682971033566198212518156744
+		40            | -11.6   | -78.0   | 60    | 0       || 74.920720651851429547034443178659599205063808040294
+		40            | -11.6   | 78.0    | 60    | 0       || 74.920720651851429547034443178659599205063808040294
 	}
 
 	def "Calculate the estimate beam radiation eBeamS"() {