Net Metering Bill Credit Calculator

Build a one-month dollar-credit ledger with separately metered imports and exports, different import and export rates, a beginning credit bank, an explicit credit-application limit, imported-kWh nonbypassable charges, and fixed charges. The result shows credit earned, applied, and carried forward instead of assuming that net kWh multiplied by one retail rate reproduces a U.S. utility tariff.

This is not a utility-bill replica. Real U.S. distributed-generation tariffs can net kWh within intervals, time periods, months, or annual cycles; credit at retail, avoided-cost, or other rates; apply minimum bills and nonbypassable charges; expire or cash out banks; and treat taxes, riders, demand, community solar, storage, and renewable-energy attributes differently. Use the current utility tariff and program agreement.

How the sample dollar ledger posts

The sample imports 900 kWh at 22 cents, creating a $198 energy charge. It exports 500 kWh at 8 cents, earning $40. A $20 beginning bank makes $60 available. The entered application limit allows credits against 100% of the import energy charge, so all $60 is applied and no dollar credit remains.

Imported electricity also incurs the separately entered 3-cent nonbypassable charge, or $27, and the statement has $25 of fixed charges. Those $52 are not credit-eligible in this simple model. The amount due is therefore $198 minus $60 plus $27 plus $25, or $190. The meter exchange is 400 kWh net import, but multiplying 400 by either rate would not reproduce the ledger.

Net kWh is not necessarily the billing quantity

A bidirectional meter can record imports and exports separately. A tariff might net them over an interval, billing period, or time-of-use bucket, or it might value every exported kWh separately. Under separate valuation, 900 imports at 22 cents and 500 exports at 8 cents are not economically equal to 400 imports at 22 cents.

Interval timing matters. Noon exports can receive a different value than evening imports. Monthly totals erase that sequence. Demand charges can depend on the highest interval regardless of net monthly energy. A battery can change timing and losses, but the tariff and operating controls determine value. Obtain interval data for a real analysis.

Confirm whether the bank is dollars or kilowatthours

Some programs carry a kWh balance; others carry dollars; others reset at a true-up date, pay a different surplus rate, or do not carry forward. This calculator is explicitly a dollar bank. Do not enter a 300-kWh credit as $300. A dollar bank can preserve the original export valuation, while a kWh bank may later offset energy under different rules.

Read the statement’s unit and transaction history. Record beginning balance, additions, applications, adjustments, expiration, cash-out, and ending balance. If the utility has vintage, seasonal, or time-period buckets, a single bank is insufficient. Build a bucketed model from the tariff.

Retail rate and export credit rate need definitions

An “average bill rate” obtained by dividing all charges by kWh may include fixed fees, taxes, demand, and credits. It is not automatically the marginal import rate. Likewise, export compensation may vary by hour, season, program year, project size, technology, interconnection date, or subscriber class. Enter rates that correspond to the modeled energy line.

Tiered rates require stepwise import calculation; time-of-use requires period-specific imports and exports. Fuel adjustments and riders may be credit-eligible or excluded. If export credit includes environmental attributes or a performance incentive, treat that according to program documentation. Do not double count a renewable-energy certificate value.

Use a tariff map before building a larger model

Solar production is not the same as exported energy

PV energy can be consumed instantly by the home, charge a battery, be lost in conversion, or export to the grid. Utility exports are only one path. Without solar, the home might have purchased more than 900 kWh; this statement alone does not reveal that counterfactual. Therefore the result does not label the $40 export credit as total solar savings.

A defensible energy balance tracks PV production, direct self-consumption, battery charge/discharge, grid import, grid export, conversion losses, curtailment, and matching timestamps. Compare inverter and utility meters carefully because time zones, intervals, accuracy, and billing cutoffs can differ.

Minimum bills and nonbypassable charges need separate lines

A minimum bill can be a floor on certain charges rather than a flat fee added every month. The single fixed-charge input cannot express every minimum-bill structure. Nonbypassable charges can apply to gross imports, net imports, or another billing determinant and may include public-purpose, wildfire, transition, or program costs.

The sample applies one per-kWh charge to gross imports and excludes it from credits. That is an explicit modeling choice, not a universal rule. If the tariff uses a different base, create separate line items. Taxes can apply before or after credits and should be modeled according to law and utility billing.

Storage can help or hurt depending on rules

A battery can increase self-consumption, shift imports away from expensive hours, reduce demand, provide backup, or participate in a program. It also has round-trip losses, power limits, reserve settings, degradation, standby energy, and control constraints. Charging from the grid can affect export eligibility under some programs.

Do not value the same kWh as both avoided import and export credit. Model each interval: load, PV, battery state of charge, allowed charging source, import, export, tariff price, and losses. Backup value is a separate reliability objective and should not be forced into a bill-credit result.

Program rules and rates can change

Net-metering and distributed-energy policy is state-, utility-, customer-class-, and project-specific. Grandfathering may preserve older terms for a period, while expansion, transfer, system replacement, storage addition, account change, or property sale can affect eligibility. Interconnection approval does not necessarily guarantee a particular compensation term.

Use current official utility tariffs, commission orders, interconnection agreement, and state program documents. DSIRE can help locate policy summaries, but verify details with primary sources. Record effective dates and docket/tariff identifiers. For financing, test multiple future rate and policy scenarios rather than one escalator.

Build a twelve-month reconciliation

Reconcile each modeled statement to the utility bill before projecting. A one-cent rate error across thousands of kWh matters. Treat missing months and true-ups explicitly. For an unrelated U.S.

Frequently asked questions