It is very important to get a good web hosting provider to serve your OpenCart store.
A slow web store will make your visitors less likely to stay and your potential customers will end up looking for products elsewhere because of this.
The more your web store is online the more chance you have of selling your products to potential customers. If your site goes down then you can lose customers, their trust and revenue!
Web stores with 99.9% uptime and fast loading pages will rank better on Google and other search engines.
A professional hosting provider will provide better (technical) support, when it needed.