The scope of EA 10 is only meant to include the primary loads of the home, such as those captured in a whole-building energy model. If a PV system is installed and designed to serve some loads that are not captured in the model, the PV output should be discounted for the purposes of EA 10. Specifically, the project team (including the PV designer) should estimate the electricity consumption associated with both the in-home and relevant exterior loads that are served by the PV system. The PV output used in EA 10 should be weighted based on the estimated percentage of the total electricity consumption in the home. For example, if the estimated electricity consumption in the home is 10,000 kWh/year and the estimated electricity consumption of exterior loads (e.g. pool, lighting, detached garage) is 5,000 kWh/year, then only two-thirds of the PV output should be counted in the EA 10 calculation. If the PV system is wired in such a way that it\'s easy to disentangle the PV serving the home from the PV serving exterior loads, then this weighting approach is not needed; in this case, no credit should be awarded for the PV capacity that only serves exterior loads.
**Updated January 1, 2014
For single-family homes using the performance path (EA 1), if the PV is serving an ancillary load that is not already included in the energy model, this ancillary load must be added to the total loads in both the reference and rated home.
For single-family homes using the prescriptive path (EA 10), any ancillary loads served by the PV system must be added to the annual reference electric load before doing the calculation to determining percent savings.