My website is more than a year old and Google Webmaster Tools reports that I have over 1500 links to the site, yet my Google PageRank is still zero.
Is my website being penalised and why is my PageRank not updating?
Google PageRank has not been updated for a while (since 4 February 2013) and probably won't be updated anymore.
Moreover, it's not because the website has not a PageRank updated than it's penalized. Anyway, I checked and the website is not penalized.
If I were you, I should forget this PageRank concept. Nowadays, it's not accurate anymore.
Regular blog update with high quality & unique content can improve your site Pagerank.