can we get the temperature of the air around the outside of a roof surface?

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If you search in this page on simple PV you will find a section on Integrated Exterior Vented Cavity, which is one of 5 methods available to calculate module operating temperatures. This is will let you do building integrated PV with a naturally vented air cavity. I believe there is an example file installed with E+ as well.

If the user specifies “Integrated Exterior Vented Cavity” for this parameter, then the temperature result for the exterior cavity is used for the cell temperature. Also the energy exported from the baffle surface as electricity is deprecated using a source term in the baffle’s temperature modeling.

The local outdoor atmospheric properties (temperature and wind speed) are calculated independently for each surface, zone, and outdoor air node. The calculations of these properties are described in the Engineering Reference here. These calculations can be controlled with coefficients of a Site:HeightVariation object.

The calculated properties can be output from the model by requesting the output variables described here.

Hello Oat; I'm also interested in the answer to your question "...does E+ assume that the temperature of the air around the entire building envelope is uniform and equals to the air temperature as specified in the epw weather file for a given hour?"

My assumption was that E+ did not perform complex exterior air calcs (like finite element or finite volume solutions)...perhaps I am mistaken!

I was searching around in the E+ engineering reference and came across the following exterior surface object SurfaceProperty:ExteriorNaturalVentedCavity and felt it might be of use.