The size of the gap
Everything here scales with it. A 24¢ gap in a high-rate state with a poor export credit is worth nearly twice a 13.4¢ gap on the same export volume. Find your real export credit before anything else.
HyreSolar tools
NEM 3.0 and Net Billing: What Your Exported Power Is Worth
California calls it NEM 3.0. Other states call it net billing, net purchase and sale, or a buyback tariff. The arithmetic is the same everywhere.
Under NEM 3.0 in California, and under net billing tariffs elsewhere, your exports are credited below what you pay to import. A battery captures that difference by storing kilowatt-hours instead of selling them cheaply. This puts a ceiling on that value. It is a ceiling, not a forecast.
What this returns at the defaults
Importing at 18.44¢ and exporting at 5¢ leaves a 13.4¢ gap. On 6,000 exported kilowatt-hours that is a ceiling of $806 a year, or about $726 after a round-trip efficiency allowance. On a California-style 32¢ import and 8¢ export the ceiling is $1,440. If your export credit equals your import rate, the answer is zero and a battery has to justify itself on backup alone.
Last updated . Data as of 23 August 2026.
Export gap model
The ceiling on rate arbitrage, before the battery's own cost.
— Ceiling after round-trip
— Rate gap
— Theoretical ceiling
A ceiling, not a forecast. Backup value is not priced here.
HyreSolar does not sell batteries and names no brand in this model.
What this ceiling does and does not tell you
The self-consumption ceiling is a maximum, not an expectation. It assumes every exported kilowatt-hour could instead have been stored and used later. In reality a battery has a finite capacity, it is sometimes already full when the surplus arrives, and it is sometimes already empty when the evening load turns up. Real capture is a fraction of this number.
The 10% haircut is a round-trip efficiency allowance and nothing more. Energy in is not energy out: a fraction is lost charging and discharging. It is not a forecast of cycling behaviour, reserve settings or degradation, all of which reduce the figure further.
If the gap is zero the tool says so, and that is the useful answer. Under genuine one-for-one net metering, a stored kilowatt-hour and an exported kilowatt-hour are worth the same, so arbitrage value is nil. That does not make a battery pointless, it makes backup the reason to buy one, and this calculator cannot price backup.
No gapFull retail net metering, or close. Storage has no arbitrage case here. Judge it on outage protection instead.
5 to 15¢ gapTypical net billing. There is real value to capture and it is worth modelling against the battery’s installed cost and warranty.
Over 20¢ gapA high-rate state with a low export credit. The arbitrage case is strongest here and the ceiling can exceed $1,400 a year on ordinary export volumes.
How to use this calculator
Every input below is a number you can find, not one you have to guess. This is where each one comes from.
- 01
Enter your import rate in cents
The blended rate you pay per kilowatt-hour: total bill divided by total kilowatt-hours, so delivery and fixed charges are inside it.
Where to find it Your utility bill. Delivery is frequently the larger half, our own measurement puts it at 53.2% of the residential bill across 14.7 million customers, so the supply line alone understates the gap.
- 02
Enter your export credit in cents
What the utility actually pays you per exported kilowatt-hour. Under net billing this is usually an avoided-cost or wholesale-linked figure well below retail.
Where to find it Your interconnection agreement or the tariff sheet for your rate schedule. It may vary by hour or season, in which case use an annual average and treat the result as rougher.
- 03
Enter annual exported kilowatt-hours
Not total production. Only the share that leaves the property because nobody was using it at the time.
Where to find it Your monitoring platform or your utility bill, which usually shows kWh delivered and kWh received separately. Without a battery, exports are commonly half or more of production on a system sized for full offset.
- 04
Read the ceiling, then discount it
The realistic figure already includes a round-trip efficiency allowance. Real capture is lower still because a battery cannot always be in the right state of charge.
Where to find it Compare the ceiling against the installed cost of the storage divided by its warranted years. If the ceiling alone does not clear that, the arbitrage case does not close.
- 05
Price backup separately
This tool deliberately does not value outage protection, because that value is personal and no primary source sets a price on it.
Where to find it Our battery versus generator page covers what backup actually buys and the safety record of the alternative.
How this calculator works
Find the gap
Import rate minus export credit. If the result is zero or negative there is nothing to capture and the tool says so.
Multiply by exports
Gap × annual exported kilowatt-hours gives the theoretical ceiling.
Take off a round-trip allowance
A 10% deduction for energy lost charging and discharging.
Compare against the battery
Installed cost over warranted life. This tool does not do that step for you, because it does not know your quote.
The formula, in full
gap = import rate − export credit, in dollars per kWh. ceiling = gap × annual exported kWh. realistic = ceiling × 0.9, where the 0.9 is a round-trip efficiency allowance.
A worked example, start to finish
A household importing at the national average residential rate and exporting under a net billing tariff paying 5 cents, with 6,000 kilowatt-hours leaving the property each year.
Inputs
- Import rate
- 18.44 ¢ / kWh
- Export credit
- 5.00 ¢ / kWh
- Gap
- 13.44 ¢ / kWh
- Annual exports
- 6,000 kWh
- Theoretical ceiling
- $806 / yr
- Round-trip allowance
- −10%
Result
$726 / yr
That is the most a battery could return on rate arbitrage here, before its own cost. It assumes perfect timing every day of the year. A real battery misses surpluses when it is already full and misses evening loads when it is already empty, so treat this as the number the real answer sits below.
How the answer moves
One input changed at a time. Every figure is computed by the calculator on this page.
| Situation | Gap | Ceiling | After round-trip |
|---|---|---|---|
| Base case18.44¢ import, 5¢ export, 6,000 kWh | 13.4¢ | $806 | $726 |
| Export credit 2¢ | 16.4¢ | $986 | $888 |
| Export credit 10¢ | 8.4¢ | $506 | $456 |
| Export credit equals import | none | $0 | $0 |
| Half the exports, 3,000 kWh | 13.4¢ | $403 | $363 |
| High-rate state, 32¢ import, 8¢ export | 24.0¢ | $1,440 | $1,296 |
The row that matters most is the fourth. Under full retail net metering the arbitrage value is exactly zero, because a kilowatt-hour stored and a kilowatt-hour exported are worth the same. Every battery pitch that leans on savings should be checked against your actual export credit first.
What moves this number most
Ranked. A proposal can change any of these without saying anything untrue, so these are the inputs to check first.
How much you actually export
Linear. Halving exports halves the ceiling. A system sized closer to your daytime load exports less and therefore has less for a battery to capture, which is a real argument against oversizing and then buying storage to fix it.
Whether your tariff is net metering or net billing
This is the binary that decides whether there is a case at all. Our page on the three crediting regimes sets out how to tell which you are on.
Time-of-use structure, which is not in this model
If your import rate varies by hour, a battery can also shift consumption from expensive hours to cheap ones, value this tool does not capture. See time-of-use rates and solar.
Whether your rules are about to change
Export credits are set by tariff and tariffs change. A calculation built on today’s credit is only as durable as the tariff. Read what happens when net metering ends.
Backup, which is worth something this cannot price
Outage protection is frequently the actual reason people buy storage, and no primary source sets a dollar value on it. We refuse to invent one.
Common mistakes with this calculation
Using the supply rate as the import rate
Delivery charges are frequently the larger half of the bill and solar offsets kilowatt-hours carrying both. Using only the energy line understates the gap and undervalues the battery.
Using total production instead of exports
Only the kilowatt-hours that actually leave the property are available for a battery to capture. Everything you already self-consume is earning full retail value with no storage involved.
Treating the ceiling as an expectation
It assumes perfect daily timing. A real battery is sometimes full when the surplus arrives and empty when the load turns up. The realistic line is still a ceiling, just a slightly lower one.
Buying storage for arbitrage under full net metering
If your export credit equals your import rate, there is no rate gap and the arbitrage value is zero. That is not an argument against a battery, it is an argument for judging it on backup instead.
Ignoring the battery’s own cost and warranted life
This tool gives you one side of the comparison. Divide the installed cost by the warranted years and see whether the ceiling clears it. Frequently it does not on arbitrage alone.
Assuming the export credit is fixed for the life of the system
It is a tariff term, and tariffs are revised. Ask whether your credit is locked for a period, and what happens when that period ends.
The thing this calculation rests on
Your export credit is a regulatory decision, not a property of your system
Everything on this page scales with one number you do not control and cannot lock by buying better equipment. It is worth understanding who sets it and how it moves.
HyreSolar analysis. A solar array is a physical object with predictable behaviour. The value of the electricity it exports is not a physical quantity at all — it is a price set in a tariff, by a regulator, after a proceeding. That is an uncomfortable thing to build a twenty-year investment case on, and it is routinely presented in sales material as though it were as fixed as the hardware.
Source fact. The clearest documented example in the country is California’s. In decision D.22-12-056, adopted 15 December 2022, the California Public Utilities Commission replaced NEM 2 with a net billing tariff for customers of PG&E, SCE and SDG&E. Under it, exports are compensated from the CPUC Avoided Cost Calculator — a calculation of what the utility avoided by not buying that energy elsewhere — rather than at the retail rate the customer pays for imports. The decision also provides an export compensation rate lock-in of 9 years from the date of interconnection, effective retroactively to 15 April 2023.
HyreSolar analysis. Two things in that paragraph deserve attention. The first is that the change was made after hundreds of thousands of systems were already installed, which is what a lock-in period exists to manage. The second is that a lock-in is finite. Nine years is a long time and it is not twenty-five. Any model that assumes today’s export credit holds for the full life of the array is assuming something the tariff itself does not promise.
HyreSolar analysis. We are not saying an export credit will be cut where you live. We have no basis for that and we are not going to invent one. We are saying the export credit is the kind of number that gets revised, and that a battery bought to capture a gap is an asset whose value moves with somebody else’s decision. Our study on California’s transition works through what actually happened there.
The useful next step. Ask your utility two questions in writing: what your export credit is today, and whether it is locked for a stated period. If it is locked, put the end date in your calendar. If it is not, run this calculator a second time at a lower credit and see whether the battery still makes sense.
Linear, and steeper than people expect
The ceiling is a straight line, and it hits zero exactly at full net metering
There is no clever region in the middle. The value a battery can capture from rate arbitrage is directly proportional to the gap, and the gap is set entirely by two numbers.
HyreSolar calculation. Holding the import rate at the EIA national residential average of 18.44¢ and exports at 6,000 kWh, the annual ceiling runs from about $996 where exports earn nothing at all, down to exactly zero where the export credit equals the import rate. Every point in between is on the same straight line. This is arithmetic on our own model, using an EIA rate with a stated vintage; it is not a figure any household has reported to us.
HyreSolar analysis. The linearity is the useful part, because it means you do not need a model to sanity-check a battery pitch. If somebody claims a battery will save you a given amount each year, divide that by your annual exported kilowatt-hours. The result is the implied gap in dollars per kilowatt-hour. If it exceeds the difference between what you pay and what you are credited, the claim is arithmetically impossible before you consider whether the battery could ever be in the right state of charge.
HyreSolar analysis. The zero case is the one worth sitting with. Under genuine one-for-one net metering the grid is already acting as a perfect, lossless, free battery with unlimited capacity. No physical battery can beat that on arbitrage, because there is nothing to arbitrage. A battery in that situation has exactly one job, which is keeping the lights on when the grid is down, and it should be judged on that alone.
Illustrative chart. Export volume and import rate are held constant at values chosen to make the relationship visible; they are not defaults for your household.
The mechanism, not the caveat
Why a real battery never reaches the ceiling
The page says repeatedly that this is a maximum. Here is the physical reason, which is more useful than the warning.
HyreSolar analysis. The ceiling assumes that every exported kilowatt-hour could instead have been stored and used later. For that to hold, the battery would need spare capacity at the exact moment each surplus kilowatt-hour arrives, and an unmet load at the exact moment it wants to discharge. Neither is generally true.
HyreSolar analysis. On a clear day in spring, a system sized for annual offset produces a large midday surplus. A battery fills, and then it is full — every kilowatt-hour after that exports at the low credit exactly as it would have without the battery. On a cold dark week the battery never fills at all, and the evening load it was meant to cover is served from the grid at the import rate. The days on which a battery is exactly the right size are the shoulder days, and there are fewer of them than the annual arithmetic implies.
HyreSolar analysis. There is a second reason, which is that most households do not let a battery run flat. If you keep a reserve for outages — which is often the actual reason the battery is there — that reserve is capacity permanently unavailable for arbitrage. A larger reserve buys more resilience and less saving, and the trade is yours to make.
The useful next step. If an installer’s battery model shows capture close to the theoretical ceiling, ask what state-of-charge assumptions it used and what reserve it left. Those are answerable questions and the answers change the number substantially.
Illustrative chart. The shaded share is not a finding. We publish no capture-rate figure because we have measured none.
Read your tariff sheet against this
The three crediting regimes, and what each does to this calculation
Before running the numbers, establish which of these describes your utility. The answer changes the arbitrage case from substantial to nil.
| Regime | How exports are credited | What it does to the gap | What its absence from a sales pitch means |
|---|---|---|---|
| Full retail net metering | A kilowatt-hour exported offsets a kilowatt-hour imported, one for one. | No gap. The arbitrage ceiling is exactly zero. | A battery pitched on "savings" here has no arbitrage mechanism to point at. Ask what the saving actually is. |
| Net billing | Exports credited at an avoided-cost or wholesale-linked figure below retail, often varying by hour. | A real gap, frequently a large one. This is the regime the calculator is built for. | If nobody has told you which hours pay what, the annual average being used may hide most of the variation. |
| Buyback or avoided-cost purchase | The utility buys exports outright at a set rate, sometimes on a separate meter. | A gap, and usually a wide and stable one. | Ask whether the buyback rate is fixed by contract or reset periodically. It is frequently the latter. |
Our page on the three regimes sets out how to tell which one your utility uses from the documents you already have.
Before signing for storage
What to ask before buying a battery for savings
Every question here has a documentary answer, from your utility or from the quote. None of them requires you to argue about technology.
- What is my export credit, in cents, today?
From the tariff sheet for your rate schedule or your interconnection agreement. If it varies by hour, ask for the schedule rather than an average.
- Is that credit locked, and for how long?
California’s net billing tariff locks the export compensation rate for 9 years from the date of interconnection. Other jurisdictions differ. A lock with an end date is still a lock worth knowing about.
- How many kilowatt-hours do I actually export in a year?
Not production — exports. Your bill usually shows kWh delivered and kWh received separately. This is the quantity the whole calculation multiplies by.
- What usable capacity does this battery have, as opposed to nameplate?
These are different numbers and only one of them does any work. Ask for the usable figure in kilowatt-hours and the depth of discharge it assumes.
- What reserve will be held back for backup, and can I change it?
Capacity held in reserve is capacity not available for arbitrage. The trade-off is real and you should be the one making it.
- What is the warranty, in years and in throughput?
Batteries are typically warranted on both. Divide the installed cost by the warranted years and compare that against the ceiling this page gives you.
- A battery quote justified by a savings figure with no export credit stated
The saving cannot be checked without it. This is the single most common gap in a storage pitch and it is entirely fixable by asking.
- A battery pitched for savings while you are on full retail net metering
There is no rate gap to capture. The honest case for storage here is backup, and it should be made on those terms.
The real blind spots
What this calculator cannot do
The net billing calculator computes one bound on one mechanism. Here is everything outside that bound, stated plainly rather than buried.
It cannot price backup power
Deliberately. What an outage costs you depends on your medical equipment, your work, your climate, whether you have a well pump, and how long outages typically last where you live.
No primary source sets a dollar value on that and we will not invent one. Our page on batteries versus generators covers the comparison without pretending to price it.
It cannot model time-of-use shifting
If your import rate varies by hour, a battery can move consumption out of expensive periods. That is genuine value and it is entirely outside this model, which assumes one flat rate.
Our page on time-of-use rates and solar covers the mechanism.
It cannot see the battery
Cost, usable capacity, round-trip efficiency in your climate, warranted throughput and degradation are all outside it. The 10% deduction is a round-trip allowance and nothing more.
For sizing rather than valuing, use the battery sizing calculator.
It assumes flat rates all year
One import rate, one export credit, twelve months. Real tariffs have seasons, peak periods and sometimes different export rates for summer evenings than for spring middays.
Where the variation is wide, an annual average understates what a well-controlled battery can do and overstates what a poorly controlled one will.
It cannot tell you the rules will hold
The entire calculation rests on an export credit that a regulator can revise, as California did in D.22-12-056.
A lock-in period, where one exists, is the most valuable piece of information in this whole exercise, and it is the one least likely to appear in a sales conversation.
It holds no data on batteries or installers
HyreSolar does not install solar, does not lend, is not a utility, and holds no dataset of quotes, bids or completed installations. Nothing here is a price we have observed. That is also why these tools are free to tell you that the answer is to do nothing.
No brand is named in this model, no product is recommended, and no installer pays to appear here — because none appear here at all.
Important: this is a planning estimate
- A ceiling, not a forecast. It assumes every exported kilowatt-hour could have been stored and used instead.
- The 10% deduction is a round-trip efficiency allowance only. It is not a model of cycling, reserve settings or degradation.
- Does not value backup power, time-of-use shifting or demand charge avoidance.
- Does not include the cost, warranty or usable capacity of any battery.
- Assumes a single flat import rate and a single flat export credit for the whole year.
Questions this calculator answers
Is this a NEM 3.0 calculator?
Yes. NEM 3.0 is California’s name for a net billing tariff — exports are credited at an avoided-cost value well below the retail rate rather than one-for-one. That is exactly the gap this calculator models. Enter your import rate and your export credit and the arithmetic is the same whether your utility calls it NEM 3.0, net billing, net purchase and sale, or a buyback rate. What differs between states is the export credit itself, which is why it is an input rather than a number we publish.
What changed between NEM 2.0 and NEM 3.0?
Under NEM 2.0 an exported kilowatt-hour offset an imported one at close to retail, so the gap this tool measures was near zero and a battery had no arbitrage case. Under NEM 3.0 exports are credited at a much lower avoided-cost value, which opens a gap — and it is that gap, not the panels, that creates the economic argument for storage. Run the calculator with your export credit set to your retail rate to see the NEM 2.0 case: the ceiling goes to zero.
What is net billing and how is it different from net metering?
Under net metering your exports are credited at or near the retail rate, so a kilowatt-hour sent out is worth about the same as one brought in. Under net billing they are credited at a lower, usually avoided-cost figure. That difference is the entire subject of this calculator: net metering leaves no gap to capture, net billing leaves a large one.
How much can a battery save me under net billing?
At most, the gap between your import rate and your export credit multiplied by the kilowatt-hours you export. At 18.44¢ import, 5¢ export and 6,000 kWh exported, that ceiling is $806 a year, or about $726 after a round-trip efficiency allowance. Real capture is lower because a battery cannot always be in the right state of charge.
Why does the tool say there is no gap to capture?
Because you entered an export credit at or above your import rate. Under those terms a stored kilowatt-hour and an exported one are worth the same, so storing instead of exporting saves nothing on rate arbitrage. A battery would then have to justify itself on backup power alone, which this tool does not price.
What is the 10% haircut?
A round-trip efficiency allowance. Energy put into a battery does not all come back out, some is lost charging and discharging. It is not a forecast of how often the battery cycles, what reserve you set, or how it degrades, all of which reduce real capture further.
Where do I find my export credit?
Your interconnection agreement or the tariff sheet for your rate schedule, both of which your utility publishes. Your bill may also show kWh delivered and kWh received separately. If the credit varies by hour or season, use an annual average and treat the result as approximate.
Should I use my production figure or my export figure?
Exports only. Kilowatt-hours you consume as they are generated already earn full retail value without any storage, so they are not available for a battery to capture. Using total production can overstate the ceiling by a factor of two.
Does this include time-of-use savings?
No. If your import rate varies by hour, a battery can also shift consumption out of expensive periods, which is genuine value this model does not capture. Our time-of-use page covers that mechanism separately.
Does this include backup power?
No, deliberately. Outage protection is frequently the real reason people buy storage, and no primary source sets a dollar value on it. We would rather leave it out than invent a figure. Judge backup on what an outage actually costs you.
Is my export credit locked in?
Not necessarily. It is a term of a tariff, and tariffs are revised by regulators. Ask whether your credit is fixed for a stated period and what happens at the end of it. Our page on the end of net metering covers how these transitions have actually been handled.
Should I just export less instead of buying a battery?
Frequently yes, and it is the cheaper answer. A system sized closer to your daytime load exports less and needs less storage to capture. Oversizing an array and then buying a battery to rescue the exports is an expensive way to reach the same place.
The research behind these numbers
Every assumption in this calculator is argued from primary sources somewhere in our research library. These are the pages that matter for this one.
- Net metering, net billing and buyback The three crediting regimes, how to tell which you are on, and why the difference decides this calculation.
- What happens when net metering ends Why an export credit is a tariff term rather than a permanent feature of your system.
- Net metering statistics Coverage and capacity computed from EIA-861, so you can see how your state compares.
- Battery backup versus a generator The value this calculator deliberately refuses to price, and the federal safety record of the alternative.
- Time-of-use rates and solar The second thing a battery can do that this model does not capture.
- Solar battery statistics How many net-metered systems actually pair storage, by state, from EIA-861.
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Written and audited by
HyreSolar Research
Primary-source research, data analysis and fact checking
We are a research desk, not a sales floor. We read the statute, the tariff, the code section, the federal filing or the manufacturer data sheet ourselves, and we publish the figure with the document it came from and the date we retrieved it. Where a number cannot be traced to a primary source, we publish the shorter page and say what we could not verify. That rule has cost us whole sections, and it is the reason the rest can be trusted.
- 160
- primary sources read and cited
- 220
- figures with a retrieval date
- 115
- federal and state government sources
- 66
- researched pages published
How this desk works
- Primary sources only. Statutes from the legislature’s own publishing system, federal data from the agency that collects it, code text from the adopted edition, manufacturer claims from the data sheet. We do not cite an article that cites a source; we go and read the source.
- Every figure carries its provenance. A named document and the date we retrieved it, so you can check it and so you know how old it is. Retrieval dates are not decoration: an EIA rate from May is a different fact from an EIA rate from August.
- We publish what we could not verify. Every research page carries a section naming the things we tried to establish and could not, and why. A paywalled standard, a state website that refused the request, a manufacturer that publishes no figure at all.
- We separate measurement from modelling from our own reasoning, and label which is which on the page. A laboratory measurement, an assumption inside a modelling tool and our own inference are three different kinds of claim and they are never presented as one.
- We do not sell solar, and we take no payment for placement, ranking or a favourable mention. Nobody buys a position on this site.
Data as of 23 August 2026. Authorship on this site is organisational: the analysis belongs to the desk rather than to a named individual, and we do not publish credentials we do not hold. Our editorial policy sets out how we source, date and correct what we publish.
Data and sources
- Electric Power Monthly, Table 5.6.A (EIA, retrieved 2026-08-23. Default 18.44¢/kWh national residential average, May 2026 data.)
- Form EIA-861, Net Metering (EIA, retrieved 2026-08-23. Underlying data for our net metering and storage attachment analysis.)