What is a true-up bill?
A true-up is the annual reconciliation on a solar electricity account: rather than settling every month, your utility tracks twelve months of imports, exports and credits and then bills the net in one statement on your solar anniversary — which is why it can arrive large even though your monthly bills looked small all year.
Why utilities settle annually at all
Solar production is seasonal. A system that overproduces heavily in June and underproduces in December would, under strict monthly settlement, hand you a credit you could not use in summer and a bill you could not offset in winter. Annual netting smooths that: the summer surplus carries forward and covers the winter shortfall.
That is genuinely in your favour, and it is why annual true-up exists. The catch is purely psychological and entirely predictable — twelve months of small statements followed by one real one. Nothing has gone wrong. The bill was accruing the whole time; you were just not being asked for it.
What the statement is actually adding up
| Line | What it is | Can solar reduce it? |
|---|---|---|
| Fixed / customer charge | A flat monthly amount for being connected. | No |
| Energy imported | kWh you pulled from the grid, at your retail rate. | Yes — by consuming your own production instead |
| Energy exported | kWh you sent to the grid, credited at your export rate. | It is the credit |
| Net energy charge | Imports minus credits across the twelve months. | This is the true-up |
| Surplus treatment | What happens if credits exceed charges: paid out low, carried, or expired. | Depends on your tariff |
A small monthly bill is not evidence of a small year. Under annual settlement most of what you see monthly is the fixed charge. The number that tells you how the year is going is the running credit balance, which is printed on the statement and almost never read.
What causes a true-up shock
Four causes, in roughly the order they show up.
Exports credited below retail
You sold surplus at one price and bought back at a higher one. Under net billing that gap is the single largest driver, and it is a tariff feature rather than a mistake. It is also why oversizing rarely pays.
The system was sized to old usage
An EV, a heat pump, a new occupant, a home office. Any of them can add thousands of kWh a year to a house sized for the old pattern, and the array cannot grow to match.
Time-of-day pricing
Where import and export prices vary by hour, midday production is credited at a low-value hour while evening consumption is charged at a high-value one. The kWh net to zero and the dollars do not.
Production below the estimate
Shade that grew, soiling, a fault nobody noticed, or an estimate that was optimistic to begin with. A monitoring app that nobody opens is how a dead string goes unnoticed for a year.
California, PG&E and why true-up gets searched most there
California generates a disproportionate share of the questions about true-up bills for two reasons that compound. It has among the highest residential electricity rates in the country — 31.8¢ per kWh on the statewide average — so every kWh of shortfall is expensive. And california moved to NEM 3.0 net billing in 2023, which pays roughly 75% less for exported power — solar there now pays best when paired with a battery and heavy self-consumption.
Put those together and the gap between what you pay to import and what you receive to export is wide, and it accumulates for twelve months before anyone shows you a total. It is also why batteries changed the arithmetic there: storing midday production to use in the evening turns an export credited at a low rate into an import avoided at a high one.
We are not going to quote you an average California true-up figure. The number people circulate depends on system size, household usage, tariff and vintage, and an average across those is not information — it is a number that sounds like information. The PG&E page goes through what the settlement is made of, and the California cost page carries the rate and payback modelling.
How to read yours before it lands
- 01Find your true-up month. It is your interconnection anniversary, not January, and it is printed on your statement.
- 02Read the running balance, not the amount due. The cumulative credit or charge position tells you where the year is heading with months left to act on it.
- 03Compare production against the original estimate. If the array is materially below what was modelled, that is a warranty conversation, and it is easier to have with a full year of data.
- 04Ask what happens to a surplus. Paid out, carried forward, or expired — all three exist, and it changes whether shifting more load into daylight hours is worth doing.
- 05Shift what you can into production hours. Under any below-retail export rule, a kWh you consume yourself is worth more than a kWh you sell. Dishwashers, laundry, pool pumps and EV charging are the easy ones.
Common questions
What is a true-up bill?
A true-up is the once-a-year reconciliation on a solar electricity account. Instead of settling every month, the utility tracks twelve months of what you imported, what you exported and what those exports were credited at, then settles the whole year in a single statement. If your production covered your usage you may owe little; if it did not, the shortfall arrives all at once.
Why is my true-up bill so high?
Usually one of four reasons: the system was sized to a usage level you have since exceeded, exports were credited well below the retail rate you paid to import, production came at hours when you were not using it under a time-of-day tariff, or the monthly statements you had been paying were only fixed charges and gave a misleading impression of the year. A large true-up is nearly always a sizing or an export-value problem, not a fault.
When does a true-up bill arrive?
On the anniversary of your solar interconnection, not on 1 January. Your utility sets the relevant month when the system is switched on, so it is a personal date rather than a calendar one. It should be printed on your statements, and it is worth knowing in advance so it is not a surprise.
Do I still get a monthly bill with solar?
Yes. Under an annual true-up arrangement the monthly statements typically show fixed charges plus a running tally of your credit position, with the energy portion deferred to the settlement. That running tally is the number to watch — it tells you months in advance roughly what the true-up will look like.
What happens to leftover solar credits at the true-up?
It depends on your utility and tariff. Some pay out a surplus at a low avoided-cost rate, which is far less than the retail rate you would have saved by consuming that power yourself. Some let surplus credit expire. Some carry it forward. This is one of the reasons oversizing a system rarely pays: the leftovers are settled on the utility's terms, not yours.
How do I avoid a true-up shock?
Read the running credit balance on every monthly statement rather than only the amount due. If the balance is trending against you by mid-year, you have months to respond — shift heavy loads into daylight hours, look at what changed in your usage, and if your utility offers monthly rather than annual settlement, work out which suits your pattern. The information is on the statement long before the bill is.