Battery ROI

How much money did your home battery actually make today?

A Home Assistant integration that multiplies every kWh your battery charges and discharges by the price at that exact moment, and shows the result as a live profit ticker.

Setup in 5 steps · Troubleshooting · How profit is calculated

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Why

Standard energy dashboards show kWh. With dynamic prices (EPEX, Nordpool, Tibber, Frank Energie, Zonneplan …) the question that matters is money: did charging at 3 AM and discharging at 7 PM pay off? Battery ROI answers that per day, per month, and since the day you installed it.

Features

• 🧮 Real profit, not an estimate: every 30 seconds, energy × the price that applied at that moment
• 🖱️ No YAML: pick your own sensors in a setup screen, change them later without losing your totals
• 🔌 Works with any battery that has a power sensor in Home Assistant (EcoFlow, Zendure, Marstek, Anker SOLIX, Victron, Huawei, SolarEdge, Sessy, Tesla Powerwall and so on), any grid meter, any dynamic price sensor, W/kW and EUR/kWh, ct/kWh or EUR/MWh
• ☀️ Solar aware: with a feed-in price and a grid meter, it knows whether a kWh replaced buying or selling
• 📈 Dashboard card included: today, this month, yesterday, last month, live €/h, monthly pace, payback and efficiency
• 🎨 Matches your theme: the card uses only Home Assistant theme variables, light and dark
• 🇳🇱 English and Dutch: setup screen and card follow your Home Assistant language
• ✏️ Visual card editor: no YAML needed on the dashboard either
• 📴 Works offline: the card and its UI library ship inside the integration, no CDN

Requirements

What	Why
Home Assistant 2024.11 or newer	Uses the current config and options flow APIs
HACS	To install and update (manual install also works)
A battery power sensor	Power into and out of the battery, as two sensors or one signed sensor
A price sensor, or your fixed tariff	A dynamic tariff sensor works best. On a fixed or peak/off-peak contract you type in the prices instead
Optional: feed-in price, grid power, solar production, state of charge	Better accuracy and more on the card

No extra Python packages are installed. The card's only library, Lit, is bundled.

Step-by-step setup

Five steps, about 10 minutes. Every step says exactly where to click in Home Assistant.

Before you start: you need HACS installed, and your battery and price sensors must already exist in Home Assistant (for example from your battery's own integration, a smart meter integration like DSMR or HomeWizard, and a price integration like Nordpool, ENTSO-e or Tibber).

Step 1 · Find your sensors

Write down the names of the sensors you'll pick in step 4.

1. Go to Settings → Devices & services → Entities (tab at the top).
2. Type in the search box to find each one:

You need	Search for	What it looks like
Battery charge power (required)	battery + power, or your battery brand	Watts that go into the battery. Some batteries have one sensor that is positive while charging and negative while discharging; that's fine
Battery discharge power	battery + power, or your battery brand	Watts that come out of the battery. Skip if the sensor above is signed
Electricity price (required, or a peak price)	price, tibber, nordpool, epex	Your current price per kWh
Grid power (recommended)	grid, p1, net, power_consumption	Your smart meter or energy monitor: watts from (+) or to (−) the grid
Feed-in price (recommended)	price	What you get per exported kWh. With a dynamic contract this is often the same price sensor
Solar production	solar, pv, inverter	Watts your panels produce right now
Battery level	battery + level, soc, state_of_charge	Battery %

Examples by brand. Entity names differ per integration and per firmware, so treat these as hints, not exact names:

Kind	Brand or integration	Sensor to look for
Battery	EcoFlow, Zendure, Anker SOLIX	separate input / output power sensors → fill both charge and discharge
Battery	Marstek, Victron, Huawei, SolarEdge, Sessy, Tesla Powerwall	one battery power sensor, positive one way and negative the other → fill charge only and set Positive power means
Grid	DSMR / Slimme meter, HomeWizard P1, P1 Monitor, Shelly EM, Tibber Pulse	power consumption minus power production, or one signed active power sensor
Solar	Enphase, SolarEdge, SMA, Growatt, Fronius, APsystems	current power or AC power of the inverter
Price	Nordpool, ENTSO-e, EnergyZero, Tibber, Frank Energie, Zonneplan, Octopus	current price

Your grid meter (or battery) only has two separate sensors, one per direction, and you want one signed sensor? Make one with a template helper (Settings → Devices & services → Helpers → Create helper → Template → Template sensor, state {{ states('sensor.power_consumption')|float(0) - states('sensor.power_production')|float(0) }}, unit W, device class Power).

Not sure which way a signed sensor goes? Open it (click the name) while the battery is charging. Positive number = "positive means charging".

Step 2 · Install Battery ROI with HACS

Click the button above and choose your Home Assistant, or do it by hand:

1. Open HACS in the sidebar.
2. Click ⋮ (top right) → Custom repositories.
3. Paste https://github.com/PeterSlijkhuis/Battery-ROI, pick type Integration, click Add.
4. Search HACS for Battery ROI, open it, click Download (bottom right).
5. HACS asks which version: keep the newest (for example v0.2.1) and click Download.

No HACS? Install by hand

Copy the folder custom_components/battery_roi from this repository into /config/custom_components/ on your Home Assistant (for example with the File editor or Samba add-on), so you end up with /config/custom_components/battery_roi/manifest.json.

Step 3 · Restart Home Assistant

1. Go to Settings → System.
2. Click the power icon (top right) → Restart Home Assistant → Restart.
3. Wait until Home Assistant is back (about a minute), then refresh your browser (Ctrl+F5). In the phone app: close the app completely and open it again. Without this the card won't show up in step 5.

Step 4 · Add the integration and pick your sensors

Click the button above, or:

1. Go to Settings → Devices & services.
2. Click + Add integration (bottom right).
3. Search for Battery ROI and click it.
4. Fill in the form with the sensors from step 1. Only the two fields marked required are needed; open the folded sections for more accuracy.
5. Click Submit.

All fields explained:

Section	Field	Required	What to enter
Battery	Charge power	✅	Power into the battery, or one signed battery power sensor
	Discharge power		Power out of the battery. Leave empty when the field above is signed
	Positive power means		Only for a signed sensor: does positive mean charging or discharging?
	State of charge		Battery %, shown on the card
Prices	Electricity price sensor (dynamic)	✅ or a peak price	EPEX, Nordpool, ENTSO-e, Tibber, Frank Energie, Zonneplan…
	Extra cost per kWh, excl. VAT		Only for raw market prices (EPEX, Nordpool): energy tax + supplier fee in EUR/kWh
	VAT %		Only for raw market prices: 21 in the Netherlands
	Peak price	✅ or a sensor	All-in price per kWh. On a single-rate contract enter your price here and leave off-peak empty. With a sensor too, it fills in whenever the sensor is unavailable
	Off-peak price		Peak/off-peak contracts only: the all-in off-peak price
	Off-peak from / until		When the off-peak price applies (default 23:00 to 07:00)
	Off-peak all weekend		On by default: Saturday and Sunday are off-peak all day, as on most peak/off-peak contracts. Switch off if yours isn't
	Feed-in price sensor		What you get per exported kWh, from a sensor
	Fixed feed-in price		Same, as a fixed amount (0 if you get nothing). Use one of the two
	Net metering until		The day net metering ends for you. Before it the feed-in price is ignored, after it it counts. Optional; leave empty if you have no net metering
Grid and solar	Grid power		Smart meter or energy monitor, + import / − export
	Solar production		Shown on the card
Battery costs	Standby power		Watts the battery uses itself that its power sensors miss
	Wear cost per kWh discharged		Purchase price ÷ (capacity in kWh × rated cycles)
	Purchase cost		What the battery cost you; adds a payback sensor and an expected payback date
	Battery installed on		Fills in the totals from Home Assistant's history from this day on, see Start from your install date

Tibber, Frank Energie, Zonneplan sensors already include tax and VAT: leave Extra cost and VAT empty.

Step 5 · Put the card on your dashboard

1. Open the dashboard where you want the card.
2. Click the pencil (top right) to edit. On the default Overview dashboard Home Assistant first asks you to Take control; confirm it.
3. Click + Add card (bottom right), type Battery ROI in the search box, and click the card.
4. The card already points at the right sensors, so there is nothing to fill in. Click Save, then Done (top right).

Prefer YAML? Add a Manual card with:

type: custom:battery-roi-card

The numbers start at €0 from the moment you finish step 4, unless you filled in Battery installed on. Read the next section before you judge them.

Your first day: why the numbers look odd

Battery ROI books money when it happens. Charging costs money right away; the payoff only arrives when the battery discharges later at a higher price. So a normal first day looks like this:

When	What you see	Why
Battery charging (night, cheap hours, or solar)	Profit slightly negative, red arrow, Spending €0.03/h	You paid for energy that is now sitting in the battery
Battery full, waiting	Profit stays put, Idle	Nothing flows, nothing is booked (except standby power, if you entered it)
Battery discharging (evening peak)	Profit climbs, turns positive, green arrow, Earning	Every kWh out replaces a kWh you would have bought at the high price
End of the day	Today is the day's real result; tomorrow it moves to Yesterday

Some numbers stay Unknown at first, on purpose:

Sensor	Shows up when	Why wait
Efficiency	1 kWh has been charged	Smaller amounts give meaningless percentages
Payback	You entered a purchase cost, 7 days have passed and profit is positive	One day says nothing about a year
Pace	From the 2nd of the month	A projection from a few hours is noise

Judge the battery on a full day, and better on a full week. A single charge without a discharge will always be red.

What to expect on your contract

Contract	Where the money comes from	What the card usually shows
Dynamic (hourly prices)	Charging in cheap hours, discharging in dear ones, plus stored solar	Clearly positive on most days
Peak/off-peak	The gap between the two prices, often only a few cents, plus stored solar	Small; can be negative when the gap is smaller than the charging losses
Single rate	Only stored solar that you would otherwise have exported for less	Only charging losses, unless you enter a feed-in price and grid power

A small or negative number on a fixed contract is not a bug: it is what the battery earns on price differences alone. The solar you keep is where the money is, so on a fixed contract a feed-in price and grid power are not optional.

Reading the card

Part of the card	Meaning
Today / This month tiles	Profit so far, with Yesterday / Last month underneath for comparison
Lifetime tile	Everything the battery has earned since you set up Battery ROI (or last pressed Reset totals), with the start date underneath
Arrow and color	Green arrow up = earned money, red arrow down = cost money, grey = (about) zero
Earning / Spending / Idle €…/h	What the battery earns or costs right now, per hour
Price, ☀ kW, 🔋 %	Current price per kWh, solar production and battery level (only if you set those sensors)
Pace	This month's profit projected to a full month
Paid back by	Month the battery has paid for itself at the rate so far, with the years left
Efficiency	kWh out ÷ kWh in; 80 to 90% is normal for home batteries

Tap a tile or the ticker to see its history graph.

After setup

I want to…	Where
Change which sensors are used	Settings → Devices & services → Battery ROI → Configure (your totals are kept)
Fill in history from the day you got the battery	Configure → Battery costs → Battery installed on, see below
Start the totals from zero	Settings → Devices & services → Battery ROI → device → Reset totals → Press
See all Battery ROI numbers	Settings → Devices & services → Battery ROI → device
See a number's history	Tap it on the card
Change what the card shows	Edit the dashboard → click the card → Edit
Update to a new version	Settings lists an update for Battery ROI at the top → click it → Install, then restart (step 3). The card then shows an orange Battery ROI was updated bar: tap it once to load the new card

Start from your install date

Had the battery before you installed Battery ROI? Fill in Battery installed on (in setup, or later via Configure → Battery costs). Battery ROI then replays Home Assistant's own history from that day and fills in Today, This month, Lifetime, energy and payback. A notification tells you when it's done and from which day it found data.

How far back it can go depends on what Home Assistant kept:

Period	What Battery ROI uses	Accuracy
Last ~10 days (the recorder's default)	Every recorded sensor change	Same as live tracking
Older	Hourly averages from long-term statistics	Close, but prices and power inside an hour are averaged
Before your sensors existed in Home Assistant	Nothing	Not counted

• Long-term statistics only exist for sensors with a state class. Most battery power sensors have one; some price sensors don't, and hours without a price are skipped.
• Hours when Home Assistant was off are skipped rather than guessed.
• The replay replaces the current totals. It runs once per date; change the date to run it again.

Numbers look wrong?

• Profit is negative on day one → normal while the battery is charging, see Your first day.
• Profit goes down while the battery is discharging → the sign is flipped. Change Positive power means (step 4 via Configure), or check your grid power sensor, then Reset totals.
• Profit is far too small or large → check the price sensor's unit (EUR/kWh, ct/kWh and EUR/MWh are handled) and that Extra cost is only filled in for raw market prices.
• Card says Battery ROI isn't set up → finish step 4, then refresh the browser.
• Card doesn't appear in the card list, or "Custom element doesn't exist: battery-roi-card" → the page was loaded before Battery ROI was installed, and Home Assistant never adds a new card to a page that is already open. In a browser press Ctrl+F5. In the phone app close the app completely (swipe it away) and open it again. Still missing? Settings → Companion app → Troubleshooting → Reset frontend cache, then close and reopen the app once more.
• "Configuration error" after Home Assistant restarted → fixed in 0.5.1. Battery ROI now also puts a copy of the card in /config/www/battery_roi and adds it as a dashboard resource, because that folder is available the moment Home Assistant starts, before integrations are loaded. If your www folder didn't exist yet, this starts working after one more restart. If you manage dashboard resources in YAML, add /local/battery_roi/battery-roi-card.js as a module resource yourself. Removing the integration removes the copy and the resource again.

Card options

The visual editor covers everything. For YAML, all keys are optional:

Option	Default
title	Battery ROI
daily	sensor.battery_roi_profit_today
monthly	sensor.battery_roi_profit_this_month
total	sensor.battery_roi_profit_total (the Lifetime tile)
rate	sensor.battery_roi_rate
payback	sensor.battery_roi_payback
efficiency	sensor.battery_roi_efficiency
price, soc	read from the rate sensor
currency	your Home Assistant currency

The pace line projects this month's profit to a full month, using the exact time elapsed; it stays hidden on the 1st.

Sensors

Sensor	Meaning
sensor.battery_roi_rate	€/h right now. Positive = earning. Attributes: price, feed-in price, grid kW, solar kW, state of charge
sensor.battery_roi_profit_today	Profit today, last_period = yesterday
sensor.battery_roi_profit_this_month	Profit this month, last_period = last month
sensor.battery_roi_profit_total	Profit since setup, tracking_since = start date
sensor.battery_roi_energy_charged	kWh into the battery
sensor.battery_roi_energy_discharged	kWh out of the battery
sensor.battery_roi_efficiency	Discharged ÷ charged, shown after 1 kWh
sensor.battery_roi_payback	Years until the battery has paid for itself at the average rate so far. Attribute paid_back_on holds the expected date. Only exists if you entered a purchase cost; shown after 7 days with positive profit
button.battery_roi_reset_totals	Start all totals from zero

Totals survive restarts. Gaps longer than 15 minutes (Home Assistant down, sensor offline) are skipped rather than guessed.

How profit is calculated

Profit is your grid bill without the battery minus your grid bill with it.

flowchart LR
    B[Battery power<br/>charge / discharge] --> S((every 30 s))
    P[Price now<br/>+ extra cost] --> S
    F[Feed-in price] -.-> S
    G[Grid power] -.-> S
    S --> R[€/h right now]
    R --> T[Today · Month · Total]

Loading

• Price sensor only. profit per hour = (discharge kW − charge kW) × price. The same price is used in both directions, which is right under net metering (salderingsregeling).
• Plus feed-in price and grid power. Battery ROI can tell solar charging from grid charging. Each kWh is valued at the price it actually displaced:

Battery is…	While the house is…	Valued at
discharging	importing from the grid	import price (avoided buying)
discharging	exporting	feed-in price (extra sold)
charging	exporting solar surplus	feed-in price (gave up selling)
charging	importing	import price (bought)

Is solar charging free? Only if you'd get nothing for exporting it. Storing a solar kWh means not selling it, so it costs whatever you'd have been paid:

• Net metering (saldering): an exported kWh cancels a bought one, so a stored solar kWh is worth the full price. Leave the feed-in fields empty, or fill them in now together with the Net metering until date so the switch happens by itself.
• No net metering: set a feed-in price (sensor or fixed) plus grid power. Solar charging then costs that feed-in price, often a few cents, and grid charging costs the full import price.
• You get nothing for export: set the fixed feed-in price to 0 and solar charging is free.

Included: round-trip losses, because you charge more kWh than you get back. Optional: the battery's own standby draw, and wear per kWh discharged (counted once, not on both charge and discharge).

Tip for the Netherlands: net metering ends on 1 January 2027. From then on a stored solar kWh is worth the feed-in price, not the import price, Enter your feed-in price, grid meter and Net metering until = 1 January 2027 once, and the numbers switch over on their own.

Tip for raw EPEX prices: they exclude energy tax, supplier fee and VAT. Fill in Extra cost per kWh and VAT: the import price becomes (market price + extra cost) × (1 + VAT).

FAQ

Why do I see "icon not available" instead of the Battery ROI icon?

The icon ships inside the integration, which Home Assistant supports from version 2026.3. On older versions the icon stays empty; everything else works.

Why not just use the battery's state of charge?

State of charge moves in whole percents and hides charging losses, so a 5 kWh battery can hide 50 Wh per step. Power sensors give the real flow.

The numbers start at zero. Can I import history?

Yes, see Start from your install date.

Can I use my own card?

Yes. All numbers are ordinary sensors, so Mushroom, Tile or any other card works.

Development

pip install -r requirements_test.txt
pytest

CI runs Home Assistant's hassfest validation and the test suite on every pull request. The screenshots above come from a real Home Assistant 2026.2 with demo sensors.

License

MIT

Contributing

Issues and pull requests are welcome at github.com/PeterSlijkhuis/Battery-ROI.