The Utility Bill Savings Tab is accessed in the upper-right of the design page:
If you have set a consumption profile and have solar panels in the design, or if you’re using FIT settings and have a completed design, the Bill Savings calculation will run when you click the simulate button.
Users can switch between three options:
- Net Energy Metering (Utility Rate) - we will use the specified pre-solar utility rate and post-solar utility rate to calculate the customer’s solar savings
- Net Energy Metering (Quick Estimate) - we will use the provided cost per kWh rate and net surplus compensation to estimate the customer’s solar savings
- Feed-In Tariff - we will calculate the customer’s pre-solar bill and revenues from the feed-in tariff. In a FIT program, all energy produced by the system is exported to the utility grid and credited at a specified rate, and all energy in the household is purchased from the grid
Net Surplus Compensation:
This is a credit for excess energy applied at the end of each True-Up period, and is often referred to as the “Avoided Cost of Energy” in utility rate structures. At the end of each True-Up period, any accrued excess kWh are compensated at the NSC rate. Users can specify whether this is paid out as cash or if it’s a credit for future billing periods.
This controls how to value any kWh exported to the grid. We assume that all energy produced by the system is first used by the house, and only production above consumption is exported.
- Retail rate - all exported kWh are credited the same as a kWh imported from the grid. This is used for traditional net metering rules
- Retail rate with fixed reduction - exported kWh are valued as the retail rate, minus the specified reduction. In addition, the imported portion of that kWh is assumed to be non-bypassable. This is used for rates like California’s NEM 2.0
- Retail rate with percentage reduction - all exported kWh are valued as the a percentage of the retail rate. For example, a 10% reduction would reduce the value of exported energy to 90% of the retail value
- Flat Export Rate - all exported kWh are valued at the specified rate, while all imported kWh are based on the selected rate schedule.
- Note - this affects all kWh during the month, while net surplus compensation is applied at the end of the month after all energy charges and credits are netted against each other. Use a flat export rate when the utility’s net metering rules specify that the crediting is done on an hourly basis - examples include Pacificorp and Provo Municipal.
How often the utility customer pays their full bill balance. This is monthly in most regions, but California has an annual billing cycle where customers pay for the total year’s worth of bill once per year, allowing production credits from one month to offset bills from previous months
How often excess production credits are expired. Most utilities are annual; if your utility doesn’t have a net metering program then this will likely be monthly (excess production is not carried forward). The specific month that credits are expired in will depend on your utility.