When running the Solar Access Insolation Analysis (cumulative over the whole year) I don't understand the result. In the case of Los Angeles (see attached file) I get 5600000Btu total. Is this for the total roof area or per sf? It doesn't appear to be for the roof area since the weather file shows this location receives around 600,000 Btu/sf/year - when I model a 1sqft area I should get approximately 600,000 Btu but this is not the case. So I'm confused - how can a 1 sqft area show 5.6MBtu?