Carried-over history
Power Insight starts counting when you add a device, but your PV system or battery has probably been running for years. Its app or web portal knows what happened since: how much was produced, exported, charged and discharged, and often how much you saved. Enter those figures and your running totals start where your system really is, not at zero.
- Open your PV system's or battery's app and note its totals: what it produced, exported, charged and discharged.
- Enter them in the device's Already accumulated: energy (kWh) section.
- Enter your Average grid tariff once, on the grid connection.
Everything below explains the details; you only need it if the form refuses your figures or the totals look surprising.
Where to enter it
Every grid, PV system and battery form ends in two optional Already accumulated sections, one for each route:
- When you add a device. Power Insight starts counting when you finish the form, so enter your app's totals up to now.
- Later, under the device's Reconfigure page. The form shows since when the device has been counted: "Power Insight has counted this device since 2026-08-14 10:32." Enter your app's totals up to that moment, so nothing is counted twice.
Every field is optional. Leave both sections empty and nothing changes.
Two routes
| Route | Section | You enter | Power Insight |
|---|---|---|---|
| 1. Energy | Already accumulated: energy (kWh) | the kWh your app shows, and the average prices | calculates the money, the same way it does for everything it counts |
| 2. Amounts | Already accumulated: amounts | the money your app shows | takes it as it is |
Use either route, or both: an amount from route 2 replaces the one route 1 would calculate. Route 1 is the better one where you can: its levelized figures follow a later change of a device's lifetime cost, and it gives amounts route 2 cannot, such as a battery's operating cost.
Route 1: energy (kWh)
| Device | Figures |
|---|---|
| Grid (the whole home) | Exported to the grid — your grid meter's total export. Average grid tariff — what a kWh from the grid cost on average over that period. |
| PV system | Produced — everything it produced, including what went into a battery or the grid. |
| Battery | Charged, Discharged, and Of which from the grid (leave empty unless your battery charges from the grid). |
A PV system's and a battery's savings are the energy they delivered into your home, valued at the Average grid tariff. You can enter it in two places:
| Where | What it is | When to use it |
|---|---|---|
| On the grid | the whole home's average, used for every PV system and battery without a tariff of its own | usually: enter it once, here |
| On a PV system or battery | that device's average; it replaces the grid's for that device | only if the device's period had a different average, for example a device added later |
Without either, a device's savings carry nothing and say no_tariff; its
export compensation, which only needs the export compensation per kWh, still
carries its part. Home Assistant then also shows a repair (Settings →
System → Repairs) naming the devices and pointing to the grid; it goes away
once every device has a tariff.
Apps disagree on what self-consumption means: some include the energy that went into a battery, some the energy that came back out of it. Power Insight credits PV energy that charges a battery to the battery, when it discharges into your home. Counting it for the PV system as well would count it twice. Produced and exported mean the same in every app, so Power Insight works out the rest itself.
Optional in route 1:
- Own export to the grid (PV system, battery) — what this device exported itself, if you know it, for example from the grid operator's annual statement for one installation. It is used as entered, and only the rest of the home's export is split between the other devices.
- Average export compensation per kWh — leave it empty to use the device's configured export compensation.
Route 2: amounts
- Savings, Export compensation (PV system, battery) — the amounts your app shows, taken as they are.
- Levelized savings — only needed when you enter amounts and no kWh.
- Total savings, Total export compensation (grid) — your app's figures for the whole home. They are split between the devices: savings in proportion to each device's calculated savings, export compensation in proportion to what each exported.
How the kWh become money
The history follows the same rules as everything Power Insight counts:
| Energy | Credited to | Saves |
|---|---|---|
| PV → home | the PV system | the grid tariff |
| PV → grid | the PV system | the export compensation |
| PV → battery | the battery, when it discharges | — |
| Battery → home | the battery | the grid tariff |
| Grid → battery | the battery | costs the grid tariff |
Example. Your PV system produced 10,000 kWh; 4,000 kWh were exported; your battery charged 2,500 kWh from the PV system and discharged 2,200 kWh; a kWh from the grid cost 0.34 on average and export paid 0.08.
| PV system | Battery | |
|---|---|---|
| Energy into the home | 10,000 − 4,000 − 2,500 = 3,500 kWh | 2,200 kWh |
| Total cost savings | 3,500 × 0.34 = 1,190.00 | 2,200 × 0.34 = 748.00 |
| Total avoided cost | 1,190.00 | 748.00 |
| Total export compensation | 4,000 × 0.08 = 320.00 | — |
Total avoided cost is the savings before a device's own costs: the same as
its savings here, since neither device paid for grid power. Had the battery
charged 500 kWh from the grid, its savings would be 748 − 500 × 0.34 =
578.00 and its avoided cost still 748.00. A battery entered as amounts only
carries no avoided cost (no_energy): its savings already have its grid
charging taken off, and without the kWh there is no telling how much.
The levelized totals also subtract what the energy cost to produce, at the device's current LCOE or LCOS. So if you later change a device's lifetime cost, its carried-over history is restated along with everything else.
Several PV systems or batteries
Your grid meter only knows what the whole home exported, so Power Insight splits it between the devices that export. It uses the same rules it uses for live readings: two PV systems that are interchangeable split in proportion to what they produced, and a battery charges only from the PV systems it is allowed to charge from.
- Enter history for every device that exports. While one of them has none, the home's export cannot be split honestly, so the history waits. Enter 0 for a device that really has none.
- A device you add later stands on its own: the home's figures cover a period it was not part of. It needs its own average grid tariff and, if it exports to the grid, its own export; a PV system's form also asks what it charged batteries with.
The split only decides which device earned what. Your combined savings are the same however it falls.
Adding a battery's history lowers the PV system's savings
Once a battery has history, the PV energy that went into it is credited to the battery, when it discharges into your home, and no longer to the PV system. So the PV system's savings drop by the value of what it charged the battery with, and the battery's savings carry what it delivered.
The combined savings drop a little too, and that is correct: a battery gives back less than it takes in, and only energy that reaches your home saves the grid price. Before the battery had history, its losses were counted as if they had saved money.
Example. Before the battery had history, the PV system's savings read 4,200. Afterwards the PV system reads 2,100 and the battery 1,800, so 3,900 combined:
| Value | |
|---|---|
| PV energy into the battery, at the grid price | 4,200 − 2,100 = 2,100 |
| Battery energy into the home, at the grid price | 1,800 |
| Lost in the battery | 300 |
The battery gave back 1,800 ÷ 2,100 ≈ 86 % of what it took in, a typical round-trip efficiency (85–92 %). To check against your app, divide the battery's Discharged by its Charged: the result should be close, allowing for the app's rounding. If it is noticeably lower, the battery may also have exported energy (that earns export compensation, in Total financial return) or charged from the grid (that costs the battery the grid price).
What your sensors show
Each total reads what Power Insight counted plus what it carries over. Its attributes show both parts:
| Attribute | Meaning |
|---|---|
carried_over | the amount carried over from your app |
carried_over_until | the moment it covers up to (when counting started) |
tracked | what Power Insight counted itself |
carried_over_missing | why a total carries nothing (see below) |
The combined totals carry the sum of every device's history, and the grid's Total export compensation carries everything the home exported.
A total carries its history only when every part of it is known. Otherwise it
carries nothing, and carried_over_missing says why:
| Reason | What is missing |
|---|---|
waiting | another device's history; carried_over_waiting_for names it |
no_energy | the kWh to calculate it from (for example an amounts-only history) |
no_tariff | an average grid tariff, on the device or on the grid |
no_export_compensation | the export compensation per kWh |
no_price | a device's lifetime cost, for a levelized total |
Long-term statistics record the carried-over amount as one step in the hour you save it. Past statistics are not rewritten.
When the form refuses the figures
The figures are checked together with every other device's history before they are saved. Small disagreements are fine: app figures are rounded and come from different meters, so figures may be up to 1 % (at least 1 kWh) apart. If they are further apart than that, the form says which device's figure is off, for example:
- a device exported more than it produced or discharged;
- the devices' own exports add up to more than the whole home exported;
- a battery charged more from local generation than the PV systems it may charge from could supply — enter its grid charging, or check what it charges from;
- the whole home's savings cannot be split — enter each device's kWh, or its own savings.
Your figures stay in the form, so you can correct the one that is off.
Good to know
- A total switched on later (for example Total financial return, a month after you added the device) starts counting when you switch it on. The time in between is not in the carried-over history either.
- A device you remove keeps its history in the combined totals.
- Not carried over: consumer totals (avoided cost, consumption cost) and a PV system's standby cost. No app reports them.