For the residential and commercial financial models, SAM assumes that electricity generated by the power system displaces purchases of electricity from the grid to meet a building or facility electric load. You specify the electricity rates on the Electricity Rates page, and the load on the Electric Load page.

SAM calculates the total annual electricity bill for two scenarios, one with and one without the power system, and then calculates the net savings as the difference between the two. SAM assumes the same electric load and electricity rate structure for both scenarios.

Notes. The electricity bill and savings values in the Metrics table are for Year one of the project cash flow. For a description of how to display annual, monthly, and hourly values, see Retail Electricity Savings.

Electricity bill without system, $/year

The total annual cost of electricity that would be purchased to meet the building or facility electric load and charge the battery with no power system.

Electricity bill with system, $/year

The the total annual cost of electricity purchased from the grid, assuming that the project purchases electricity for hours when the load is greater than system's output, or to charge the battery.

Net savings with system, $/year

The difference between costs without system and with system:

Net Savings = Cost without System - Cost with System

Note. Net savings with system is equal to Energy Value for Year one of the project cash flow.