How the net metering calculator works
Net metering lets you offset the electricity you buy from the grid with the electricity your solar system exports. This calculator takes your billing period's imported units, exported units, buy rate, sell or credit rate, fixed charges and taxes, then works out your bill under either a true 1:1 net metering scheme or a net billing scheme where exports are credited at a lower rate.
Net metering vs net billing vs feed-in tariffs
These three terms are often confused, but they work differently:
- Net metering (1:1): every exported kWh offsets one imported kWh at the same rate. If you export more than you import in a period, the surplus is usually carried forward as credit.
- Net billing: imports and exports are valued separately, typically at different rates, with exports paid or credited at a lower, wholesale-like rate compared with the retail rate you pay for imports.
- Feed-in tariff or export payment schemes: exports are paid at a fixed rate per kWh regardless of the retail import rate, sometimes as a separate cash payment rather than a bill credit. The UK's Smart Export Guarantee is one example of this style of scheme.
The formulas
For 1:1 net metering, the calculator first nets your usage:
Net units = imports - exports
If net units are positive, you owe for the shortfall at the buy rate: energy charge = net units x buy rate. If net units are negative, the surplus is valued at the sell or credit rate and either carried forward or shown as an export payment, depending on your program.
For net billing mode, imports and exports are priced separately:
Energy charge = (imports x buy rate) - (exports x sell rate)
This is floored at zero, meaning any remaining surplus becomes credit rather than a negative bill. In both modes, the full bill adds fixed charges and taxes:
Total bill = energy charge + fixed charges + taxes
The calculator also reports your effective cost per imported kWh, useful for comparing offers, and, if you enter total consumption, your self-sufficiency percentage: the share of your total usage covered directly by your own generation.
Monthly netting vs annual true-up
Some utilities net your imports and exports every billing period, typically monthly, paying out or clearing credit regularly. Others use an annual true-up, banking credit across the whole year and settling once, often near the anniversary of your interconnection. Annual true-up tends to favor solar owners, because it lets summer surplus offset winter shortfalls, whereas strict monthly netting can leave value on the table if your generation and usage are seasonal. Check your utility's specific billing cycle, since it materially changes how much a given system is worth to you.
Worked example
The table below shows one illustrative billing month under 1:1 net metering, using example figures only.
| Item | Example value |
|---|---|
| Imports | 350 kWh |
| Exports | 280 kWh |
| Net units | 70 kWh (imports exceed exports) |
| Buy rate | Example: 0.15 per kWh |
| Energy charge | Net units multiplied by buy rate |
| Fixed charges | Flat monthly amount |
| Taxes | Percentage applied to the energy charge |
| Total bill | Energy charge plus fixed charges plus taxes |
If exports had exceeded imports instead, the surplus would be credited at the sell rate and, depending on the program, carried forward to the next bill rather than paid out immediately.
Why export rates are trending downward
In many markets, regulators and utilities have been shifting away from generous 1:1 net metering toward net billing with lower export rates, reflecting the falling wholesale value of daytime solar power as more homes install panels. This trend makes two things more valuable over time: shifting your own consumption to daytime hours when your panels are producing, and adding battery storage to use more of your own generation rather than exporting it cheaply and buying it back later at a higher rate.
Regional notes
Net metering and export compensation rules vary substantially by country, and often by state, province or utility within a country:
- United States: policy is set state by state, ranging from full 1:1 net metering to net billing with lower export rates; some utilities also use time-of-use import and export pricing.
- United Kingdom: there is no traditional net metering; instead, the Smart Export Guarantee pays a per-kWh rate for exports, set individually by licensed suppliers.
- Australia: feed-in tariffs are set by state and retailer and have generally declined over recent years as solar uptake has grown.
- India: rooftop solar net metering policies are set at the state level, generally alongside central rooftop subsidy support, with system size limits and settlement periods varying by state.
- Pakistan: net metering is available through distribution companies under national rules, with export rates and interconnection limits varying by region and subject to periodic policy revisions.
Always confirm current rules with your local utility or regulator, since programs are revised periodically.
Tips to maximise value
- Run high-consumption appliances, such as washing machines, dishwashers and EV charging, during daylight hours when your panels are producing.
- Consider a battery if your export rate is much lower than your buy rate, so you can store and use surplus generation yourself.
- Ask your utility whether billing uses monthly netting or annual true-up, since this affects how much seasonal surplus is worth.
- Check for time-of-use tariffs, which can make daytime self-consumption or battery discharge during peak evening rates especially valuable.