diff --git a/.gitmodules b/.gitmodules
index 072142c..8a31a6c 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,6 +1,3 @@
-[submodule "misc/controller/ethersex"]
-	path = misc/controller/ethersex
-	url = git://github.com/volkszaehler/ethersex.git
 [submodule "misc/frontend/fnordlicht"]
 	path = misc/frontend/fnordlicht
 	url = git://github.com/steffenvogel/libfn.git
diff --git a/misc/controller/ethersex b/misc/controller/ethersex
deleted file mode 160000
index e364f1a..0000000
--- a/misc/controller/ethersex
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit e364f1aec8afdd2f6c1cc9c99890c46f81afb953
diff --git a/misc/tools/install.sh b/misc/tools/install.sh
index 3ba6863..6e74755 100755
--- a/misc/tools/install.sh
+++ b/misc/tools/install.sh
@@ -37,6 +37,8 @@ shopt -s nocasematch
 doctrine_git=git://github.com/doctrine/doctrine2.git
 doctrine_tar=http://www.doctrine-project.org/downloads/DoctrineORM-2.0.1-full.tar.gz
 vz_git=git://github.com/volkszaehler/volkszaehler.org.git
+PHP_MAJOR=`/usr/bin/php --version | /bin/grep "^PHP" | /usr/bin/awk ' { print $2 } ' | /usr/bin/cut -b 1 `
+PHP_MINOR=`/usr/bin/php --version | /bin/grep "^PHP" | /usr/bin/awk ' { print $2 } ' | /usr/bin/cut -b 3 `
 
 ask() {
 	question=$1
@@ -61,6 +63,19 @@ get_db_name() {
 	db_name=$REPLY
 }
 
+############
+# check prerequisites
+if [ ${PHP_MAJOR }-lt "5" ] ; then
+  echo you need PHP version 5.3+ to run volkszaehler
+  exit
+elif [ ${PHP_MAJOR} == "5" ]
+  if [ ${PHP_MINOR }-lt "3" ] ; then
+    echo you need PHP version 5.3+ to run volkszaehler
+    exit
+  fi
+fi
+
+
 ############
 echo
 echo doctrine setup...