After installation, run the command /usr/sbin/rtc -z $TZ, where $TZ is your timezone. The default root crontab runs /usr/sbin/rtc -c once every day.
That way your clock will give the proper time whether you boot Solaris or DOS/Windows.
But it is recommended that on systems which do not run another OS which requires the clock to run in current time to run the system clock in UTC using "/usr/sbin/rtc -c -z UTC"