Solar is a “Simple Object Library and Application Repository” for PHP5. That is, Solar is a combined class library, component suite, and application development framework.
A solution is to move the contents of /Solar/App/Public to a directory /Solar in your public directory (normally /public_html). You'll have to do this again when you upgrade Solar to a new version.
<page> in this error message is the name of the controller that Solar was unable to find. Insure that you have your [wiki:Solar/config configuration] set up properly. If you are trying to access a page that is not part of the Solar_* namespace, you are likely missing an entry in the $config['Solar_Controller_Front']['classes'] array.
Solar is community driven, so code from the community can make it into the core when it's useful to everyone at large. The process for making this happen is still being outlined, but here's a rough sketch.
Code will then be reviewed, and possibly included in the core. Continued development and adoption by the community are two reasons the code might be included. Providing hard samples (i.e., real code) that uses the code you'd like to see in Solar is a step in the right direction towards demonstrating the code's usefulness to the core.