Net billing tariffs for solar pay you for the electricity your panels export to the grid, but at a credit rate tied to what that power is worth to the utility at the moment you send it, not the full retail price you pay for electricity you pull back. That is the core change from traditional net metering, and it reshapes almost every financial assumption behind a residential solar system. A home that would have zeroed out its bill under the old rules may now cover only 60 to 70 percent of it, unless the owner adjusts how and when electricity gets used.
How Net Billing Differs From Net Metering
Under traditional net metering, your meter effectively runs backward when the panels produce more than the house uses. Every exported kilowatt-hour earns a credit at or near the retail rate, as if the grid were a free battery. Net billing breaks that one-to-one swap. The utility tracks imports and exports separately. You pay full retail for every kilowatt-hour you pull from the grid, and you receive a separate, lower credit for every kilowatt-hour you push onto it.
That credit is typically tied to the utility’s “avoided cost,” meaning what the utility would otherwise have paid to generate or buy that same electricity. The approach has a federal pedigree: the Public Utility Regulatory Policies Act requires utilities to purchase power from qualifying generators at their avoided cost.1Federal Energy Regulatory Commission. PURPA Qualifying Facilities States have adapted that principle for residential solar, so export credit rates now fluctuate by hour, season, and local grid conditions rather than sitting fixed at the retail price.
How Export Credit Rates Are Calculated
The dollar value of an exported kilowatt-hour comes out of a formula often called an avoided cost calculator. It estimates what the utility would have spent to acquire that electricity elsewhere, factoring in wholesale energy prices, the transmission and distribution costs the utility avoids when rooftop solar serves nearby homes, and sometimes an environmental value for displacing fossil generation.
What makes this genuinely different from the old system is that the value changes hour by hour. Energy exported on a hot summer evening, when air conditioners are straining the grid, can be worth several times more than energy exported at noon on a mild spring day when every rooftop system in the neighborhood is pushing out surplus. Some utilities publish fixed hourly schedules annually. Others adjust more frequently based on wholesale market conditions.
Winners and losers emerge based on when a system produces surplus. A west-facing array that peaks in late afternoon earns higher credits than a south-facing array that peaks at midday, all else equal. Households that shift heavy loads like dishwashers, laundry, and EV charging into midday hours, then export during peak evening periods, come out ahead.
Why Battery Storage Changes the Math
A battery lets you store midday production and discharge it during peak evening hours when export credits are at their highest. Without one, your system dumps surplus onto the grid at the time of day when it is worth the least. With one, you capture that energy and release it strategically.
The optimization works on two fronts. The battery reduces your grid imports during expensive peak hours by powering the home from stored solar. If capacity remains after your evening loads, it can export when the credit rate peaks. Modern inverter-battery systems can be programmed to follow time-of-use rate schedules automatically, charging from solar during low-value hours and discharging during high-value ones.
Batteries with a capacity of at least 3 kilowatt-hours also qualify for the federal Residential Clean Energy Credit alongside the panels themselves.2Internal Revenue Service. Residential Clean Energy Credit Under traditional net metering, the financial case for a battery was weak because you got full retail credit regardless of timing. Under net billing, the gap between peak and off-peak export values is often wide enough to make battery payback meaningful.
Charges Your Credits Cannot Offset
Even a perfectly optimized solar-plus-battery system will not erase your utility bill. Net billing tariffs include several charges that export credits cannot touch.
- Non-bypassable charges are small per-kilowatt-hour fees that fund public programs like low-income energy assistance and grid reliability. They apply to every kilowatt-hour you import, and no amount of solar credits can reduce them.
- Fixed monthly service fees are flat charges, typically $10 to $20, covering the cost of maintaining your physical connection to the grid, including metering, billing, and infrastructure upkeep.
- Minimum bill requirements set a floor on what any connected customer pays monthly, regardless of how much solar they produce.
These fees exist because the grid still functions as backup insurance for every solar home. When the panels are not producing at 2 a.m. or during a stretch of clouds, you draw from the same infrastructure that serves everyone else. Expect to pay somewhere between $15 and $30 per month even when your production far exceeds consumption.
System Size Limits
Net billing programs generally cap the size of eligible residential systems. The most common restriction limits a system to producing no more than 100 to 115 percent of your historical annual electricity consumption. A household using 10,000 kilowatt-hours per year would be limited to a system sized to produce roughly 10,000 to 11,500 kilowatt-hours annually.
This cap matters more than it looks. Oversizing beyond the limit can disqualify you from the net billing tariff entirely and push you onto a less favorable rate schedule. If you plan to add an electric vehicle or heat pump that will raise your future use, some utilities allow sizing based on projected consumption rather than historical usage, but you have to document those plans in your application.
Monthly Rollover and the Annual True-Up
Your utility tracks imports and exports monthly and assigns dollar values to each. If your export credits exceed your charges in a given month, the leftover credits roll forward to the next month. Accumulation continues over a 12-month billing cycle, sometimes called the relevant period.
The rollover is what makes the seasonal math work. Spring and summer credits offset the heavier grid use of winter, when production drops and heating loads climb. You still receive a monthly statement showing charges and credits, and most tariffs require you to pay any net amount owed each month rather than deferring everything to year-end.
At the end of the 12-month cycle, a settlement process reconciles your account. Remaining export credits are applied to eligible outstanding charges. If total production exceeded total consumption for the year, you may qualify for Net Surplus Compensation, a payout rate based on wholesale market prices that is significantly lower than the regular export credit rate. Unused credits beyond that are typically forfeited, and the account resets for the next annual cycle.
That forfeiture is one of the most commonly overlooked details. Under older net metering programs, rolling credits sometimes carried over indefinitely or paid out at a more generous rate. Under net billing, the annual reset means a system should be sized to roughly match your consumption over 12 months rather than dramatically overproduce.
How the Federal Tax Credit Interacts
The Residential Clean Energy Credit equals 30 percent of the cost of a new solar energy system, including panels, inverters, mounting hardware, and installation labor. Battery storage of at least 3 kilowatt-hours qualifies as well, whether installed with the panels or added later.2Internal Revenue Service. Residential Clean Energy Credit
The 30 percent rate is scheduled to hold through 2032, step down to 26 percent in 2033, and fall to 22 percent in 2034 before expiring. Some older IRS guidance materials still reference a 2025 expiration date that predates the Inflation Reduction Act’s extension. The statutory text in 26 U.S.C. ยง 25D, as amended, controls.3Office of the Law Revision Counsel. 26 USC 25D – Residential Clean Energy Credit
One detail specific to net billing: credits you receive from the utility for exported energy do not reduce your qualified expenses for the tax credit. The IRS has clarified that net metering credits do not affect your eligible cost basis.2Internal Revenue Service. Residential Clean Energy Credit If a system costs $25,000 and you receive $500 in export credits that year, the tax credit is still calculated on the full $25,000.
Cash payouts for net surplus generation at year-end are a grayer area. Bill credits that offset your electricity charges generally read as a reduction in utility costs, similar to a rebate, and most tax professionals do not treat them as taxable. If a utility characterizes the year-end payment as purchasing electricity from you, the income argument strengthens. The amounts involved are usually small, but if you receive a cash check at true-up, keep records and ask a tax professional.
Watching Out for Inflated Savings Projections
Because export credit rates change annually and are harder to predict than flat retail rates, any 20- or 25-year savings estimate under a net billing tariff rests on serious assumptions. Ask the installer to run the numbers using current export credit rates and no assumed rate increases as a conservative baseline. If the deal only pencils out with aggressive rate-increase assumptions, treat that as a warning.
A growing number of states require solar installers to disclose the methodology behind savings projections, the assumptions on future utility rate estimates, the ownership and transferability of tax credits or renewable energy certificates, and the total system cost including financing. Some states require that any projection showing future savings also include scenarios where utility rates decrease rather than showing only optimistic numbers.
Solar sold through door-to-door or in-home consultations also falls under the Federal Trade Commission’s Cooling-Off Rule, which gives you three business days to cancel for a full refund.4Federal Trade Commission. Buyers Remorse – The FTCs Cooling-Off Rule May Help Saturday counts as a business day; Sundays and federal holidays do not. The rule covers sales made at your home or at temporary locations such as home shows. It does not cover sales initiated entirely online or completed at the seller’s permanent office.