Keep in mind that running a business is not a project in itself as per definition by PMI "It's a temporary endeavor undertaken to create a unique product, service or result." However, it's completely understandable that anyone who has built a business from scratch has performed many projects in order to get the company off the ground.
In addition, it will be an issue with the application when claiming your experience that you were a sole proprietor with no partners or employees. PMI will require "a colleague, peer, client or sponsor who has intimate knowledge of the project verify this experience" for your application. PMI will reserve the right to contact the listed individuals to verify. If there is an exception to this, PMI has not made it public.