Process is too verbose, how to stop it from flooding system.log?
To follow up on bmike's answer, the app identifier is com.logitech.Solar-App.  So the code you want to put in your asl.conf is

? [= Facility com.logitech.Solar-App] ignore


If you want to confirm that I'm right about your app identifier, try:

/usr/libexec/PlistBuddy -c 'Print CFBundleIdentifier' /Applications/Solar\ App.app/Contents/Info.plist 


And if you want this to go into effect right away, you can restart syslogd with something like this:

sudo launchctl unload /System/Library/LaunchDaemons/com.apple.syslogd.plist 
sudo launchctl load /System/Library/LaunchDaemons/com.apple.syslogd.plist