A solitary Wiccan is a relatively new idea and it's one that has become the "norm" in Pagan society. More and more people are Wiccan on their own (that is, without a coven) than ever before.
The fact is that solitary Wicca really is a bit more complicated than just Wicca-by-yourself, and it should stand as it's own form of Wicca. That is because the original form of the religion, as founded by Gerald Gardner requires coven membership. Most of the ways and teachings of Wicca were private and you could only really learn them from an existing group. So that was just the way it worked. True Gardnerian covens today follow this strongly, and they can each trace their lineage back to some connection with Gardner himself. Pretty impressive if you ask me.
The very best place to start looking into solitary Wicca is with Scott Cunningham. His books were the foundation of the solitary Wiccan movement and are the best place to learn about the religion as practiced alone. His book "Wicca: A Guide for the Solitary Practitioner" and its sequel "Living Wicca: A Further Guide for the Solitary Practitioner" are still excellent classics and they were the first books to really lay out a Wiccan practice that could be undertaken by an individual. Sure there are loads of other books out there now, but let's go back to the roots.
Now, I'm talking about true Wicca here, not just any form of generic Paganism that many people follow. Many people have carved their own paths involving all kinds of spiritual practices, including witchcraft, but that doesn't make them Wiccan.
So if you are thinking about becoming a solitary Wiccan, read those 2 books to start with and realize that there is more to being Wiccan than casting spells occasionally. Wicca and Paganism are not the same thing, whether you are solitary or not.