Claire WhitakerBy Claire Whitaker

Updated November 2026

The national grid net metering tariff sets how your home solar exports are valued and credited against the electricity you pull from the grid. This guide explains how the tariff works, what to confirm before you sign up, and how to read your bill so you actually receive the credits you are owed.

What the National Grid Net Metering Tariff Covers

Under a net metering arrangement, your solar system produces electricity, your home uses what it needs first, and any surplus flows onto the grid. The utility measures that flow with a bidirectional meter and then applies a credit to your account. National Grid’s tariff defines the rate for those credits, how the credits roll forward, and what happens if you produce more than you consume over a billing period. For background on the general mechanics, see How Grid-Tied Solar Works: Net Metering, Interconnection and Outages.

Shopping for one? See our guide: National Grid Net Metering (2026): Which Is Better for Your Home?.

Step 1: Confirm Your Eligibility and System Size

Before you apply, check that your system falls within the size limits and that your service type qualifies. Tariff eligibility usually depends on system capacity relative to your historical annual usage, so an oversized array may be placed under different terms. Ask National Grid which tariff schedule applies to your account and get the answer in writing.

Step 2: Understand How Credits Are Calculated

Your bill is essentially a running balance. Each month the meter records imported and exported kilowatt-hours. Exports offset imports, and the tariff determines the value of any remaining net exports. Many customers find it easier to compare structures after reading What Is a Net Metering Credit? How It Works for Home Solar.

A quick way to check your statement:

  1. Find total kWh imported from the grid during the billing period.
  2. Find total kWh exported to the grid.
  3. Subtract exports from imports to get your net usage.
  4. Confirm the credit line matches the tariff rate printed on your rate schedule.

Step 3: Track Your Monthly Net and Rolling Credits

Summer months often produce surplus credits while winter months draw more from the grid. Under most net metering structures, unused credits carry forward, but how and when they expire depends on the tariff terms. Keep a simple spreadsheet with monthly imports, exports and credit balances so you can spot discrepancies early. If your bill keeps climbing despite solar, Why Is My Net Metering Electricity Bill Still High? 6 Causes and Fixes walks through the usual culprits.

Watch for Rate Changes

Tariffs can be revised by regulators. When a new schedule takes effect, compare your current export value against the new one, since the change may affect whether a larger or smaller system makes financial sense. Regulatory timelines are also worth tracking; see When Will Net Metering 3.0 Take Effect? Timeline for Homeowners (2026).

Common Mistakes to Avoid

  • Assuming exports are paid at the retail rate. Many tariffs credit exports at a different value than what you pay for imports.
  • Ignoring the interconnection approval. Operating before approval can delay credits and create compliance problems.
  • Skipping the annual true-up review. Check how any leftover credits are settled at the end of the year.
  • Confusing supply charges with delivery charges. Solar credits typically offset only certain line items.
  • Failing to update your account after adding batteries or expanding the array.

FAQ

Does the national grid net metering tariff pay me cash for every kWh I export?

Not necessarily. Exports are applied as credits against your usage, and the value depends on the rate schedule in effect for your account. Check your tariff sheet to see whether exports are credited at the same rate you pay for imports.

What happens to credits I do not use in a month?

Most arrangements carry unused credits forward to later billing periods. Some tariffs settle any remaining balance once a year, so confirm the exact true-up schedule with National Grid.

Do I need a professional to review my tariff choice?

For major decisions such as system size or financing, consult a licensed solar installer or energy advisor. They can model your usage and the current tariff terms against your roof’s production.

Conclusion

The national grid net metering tariff determines how much your solar exports are worth and how those credits appear on your bill. Confirm your eligibility, learn how credits are calculated, and check your statements each month. A few minutes of tracking can prevent years of lost value.

Ready to choose one?

Claire Whitaker

About Claire Whitaker

Claire Whitaker is part of our editorial team and reviews and edits our home solar guides, checking product details against manufacturer specifications and owner feedback.