A bidirectional meter is the device that makes net metering work: it keeps a separate running total of the electricity your home draws from the grid and the surplus electricity your solar system sends back, and your utility uses those two numbers to calculate your bill. A standard meter only counts incoming energy, so without the bidirectional version your utility has no record of what you exported and no basis to credit you for it.
What the Meter Actually Measures
Inside the meter, solid-state sensors detect which way electricity is moving through your service entrance. Current transformers or Hall effect sensors read the magnetic field around the conductor while the processor compares voltage and current timing thousands of times per second. When current flows one direction, the meter logs consumption. When your panels generate more than the house is using and the current reverses, the meter logs the energy as an export.
Those two measurements, delivered and received, sit in separate digital registers on non-volatile memory, so the data survives a power outage. Older mechanical meters would physically spin backward during export, which undercounted your consumption but gave the utility no clean record of how much you had sent back. The digital design fixes that by categorizing every kilowatt-hour into the correct register.
How to Read Your Meter
Most bidirectional meters have a small LCD that cycles through several screens every few seconds, each labeled with a code from the OBIS (Object Identification System) standard. The two you want are the import register and the export register. Import energy, everything you have pulled from the grid since installation, usually appears under OBIS code 1.8.0. Export energy, everything you have sent back, appears under 2.8.0.
The import number climbs whenever household demand exceeds what your panels produce. The export number climbs during sunny midday hours when production outpaces use. Many meters also show a net total for the current billing cycle and use arrows or labels like “FWD” and “REV” to indicate the direction of flow at that moment. Checking those numbers now and then gives you a running sense of your energy balance between bills. Diagnostic codes about the meter’s communication status may also appear in the rotation; those are for the utility, not you.
How Exports Turn Into Credits
Net metering is the billing arrangement that lets electricity you export offset electricity you consume. Each billing cycle your utility pulls two numbers from the meter: what you took and what you sent back. The difference is your net consumption, and that is what you pay for. If your exports exceed your imports in a given period, most utilities roll the surplus forward as a credit, so energy you banked during long summer days can offset winter bills when your panels produce less.
Net metering is governed at the state level. The Energy Policy Act of 2005 directed states to consider adopting it but did not require them to. Roughly 40 states now run some form of net metering or a successor program, and the specifics vary considerably.
What matters most to your payback is the rate at which your exports are credited. Traditional net metering credits exports at the full retail rate, so one exported kilowatt-hour cancels one imported kilowatt-hour. That one-to-one match is the arrangement most people picture when they hear the term. A growing number of states have moved to “net billing” instead, which credits exports at a lower rate tied to the utility’s avoided cost. The gap can be large. If your retail rate is 15 cents per kilowatt-hour and the avoided cost rate is 4 cents, your exports are worth about a quarter of what your imports cost you. Confirm which structure your state uses before signing a solar contract; it is one of the most consequential financial variables in the whole project.
Time-of-Use Rates
Many utilities now combine solar billing with time-of-use pricing, where electricity costs more during peak demand hours (typically late afternoon and evening) and less off-peak. Because the bidirectional meter timestamps every import and export, the utility can apply different rates based on when energy flows each way. Solar production peaks around midday, which often falls outside peak pricing windows, so your exports may earn off-peak credits while you buy expensive peak-rate power after sunset.
The Annual True-Up
At the end of a 12-month cycle, most net metering programs run an annual “true-up.” If you have accumulated more credits than you used across the year, the leftover balance is typically paid out at the wholesale rate, which is almost always well below the retail credit value. The practical consequence: sizing a system to roughly match your yearly consumption usually returns more than oversizing it, because surplus credits lose most of their value at true-up.
Getting the Meter Installed
You cannot start exporting to the grid on your own. Before your utility swaps your standard meter for a bidirectional one, you need an approved interconnection agreement, which is a formal contract setting the technical and safety terms for connecting your system to their grid.
Applications usually run through the utility’s renewable energy portal or interconnection department. You will submit technical details about the system, including the inverter’s nameplate rating and its UL 1741 certification, which verifies the inverter meets safety standards for grid-connected operation and anti-islanding. A site plan and a single-line electrical diagram, usually prepared by your installer, are standard, and many utilities also want to see your local building permit. Review fees vary; expect a few hundred dollars depending on system complexity. Some utilities absorb the meter swap cost and others bill the homeowner, so ask about the meter specifically when you apply.
On the safety side, IEEE 1547 is the national interconnection standard for distributed energy systems.1U.S. Department of Energy (Energy Efficiency and Renewable Energy). IEEE 1547 and 2030 Standards for Distributed Energy Resources The current version, IEEE 1547-2018, covers voltage regulation, power quality, and connection safety.2U.S. Department of Energy (Energy Efficiency and Renewable Energy). Highlights of IEEE Standard 1547-2018 Compliance with the National Electrical Code is also required. The most critical feature these standards enforce is anti-islanding: if the grid goes down, your system must stop exporting within seconds, so your panels do not energize a line that utility crews believe is dead.
Once the utility approves the application and installs the meter, you will receive a Permission to Operate letter. That is your green light to turn the system on. The wait between meter installation and PTO can run from a couple of weeks to two months or more. Operating before PTO is a real risk: utilities can disconnect your service, and any energy you export during that unauthorized period will not earn credits.
When the Numbers Don’t Match
Modern bidirectional meters are built to tight accuracy classes of 0.1%, 0.2%, or 0.5%, meaning a 0.5% class meter reads within half a percent of actual energy flow. For residential use, that is more than enough precision. If your bills look consistently off or your export credits run lower than your inverter’s monitoring app suggests, you can challenge the meter.
Start by asking your utility for a meter test. Many provide the first test at no charge. If the meter tests within tolerance, you typically pay for any later tests you request. If it tests out of range, the utility must correct your billing, often retroactively. Keep your own production records from the inverter app as a comparison. A gap between what your inverter reports exporting and what the meter has credited is worth investigating.
What Changes When You Add a Battery
A bidirectional meter at the service entrance measures net flow between your home and the grid. It does not distinguish between electricity coming off your panels and electricity discharging from a battery; it only sees whether power is leaving or entering the property. A battery can shift when your exports happen, holding midday solar back and pushing it to the grid during higher-value evening hours, or using it in the house so you draw less from the grid at peak rates.
Some utilities require additional metering or monitoring to track battery behavior separately, partly to verify that grid-charged batteries are not being re-exported at a profit. If you are adding storage to an existing solar system, check whether your utility needs to amend your interconnection agreement or install extra hardware. Storage rules are changing quickly, and the policies that applied when your panels went in may not be the ones in force now.