Solar energy production

Yes. The output from renewable energy systems can be allocated to different projects. The owner should generate a letter explaining the allocation of the kWhs. If you don't allocate it all you can save some for a future project.

On a related note, I have a project that is a new building located on a previous LEED certified project boundary with PV production.  The previous project had >90% offset by energy use and >100% offset by cost from renewable energy.  The project was certified under v2009, and both Optimized Energy and Renewable Energy exceeded way above maximum threshold (50% and 15% for EP).  Initially, there was no plan for campus approach, therefore no letter was written to allocate % of production to existing project.  My question is, for my new project, can I allocate part of PV production that exceeds the maximum threshold for the new project in both renewable energy production and optimized energy?

No the allocation has already occurred by default if the entire output was submitted for the previous project.

Similar question - We are developing a new project which plans on constructing a parking garage to be shared among two building on a campus.  The project is not pursuing a Group or Campus, but certifying each of the two buildings individually.  One building is a 600K+ SF office and the other is a much smaller amenities building associated with it.  The parking garage is a supporting structure for both buildings, outside of the project boundaries, but the solar array will be located there, atop the parking structure.  Can we allocated the solar generated on the parking garage, outside of the project boundary, to both buildings as a % allocation?  Does this only require a letter form ownership, or is this scenario more complicated than that?

Yes you can allocate it to your projects from outside the boundary. A letter from the owner should do it.