A diameter 10 times the size of our solar system would mean the black hole has a diameter (way) more than the distance between our sun and the closest star, 4.3 light-years away. Yikes! It would be well over 12 light-years across. Good grief.
http://curious.astro.cornell.edu/question.php?number=374
Your math is off, somehow. From the sun to Neptune is about 4.55 billion km - so give the solar system a diameter of about 9 billion km. Light travels about 300,000 km per second (sun to earth, about 8 minutes). So, 30,000 seconds times 300,000 km/sec is 9 that billion km. An object ten time bigger (that the orbit of Neptune) is covered by light in 300,000 seconds, about 3.5 days.
Or, just take this (uses a bigger solar system diameter), from your link ...
This means you could put the Solar System about 3440 times between the Sun and the nearest star taking this definition.