How it works
Power Insight needs no extra hardware and no energy meters. It watches the power sensors you already have, recalculates whenever one of them changes, and turns the result into sensors. This page explains the ideas behind those sensors without the formulas; the Advanced pages have the full details.
What goes in
For every device you add, Power Insight reads one power sensor (in W, kW
or MW) that tells it how much power flows right now. For anything to do with
money it also reads your electricity price (a sensor or an
input_number), plus a few numbers you type in once, such as what you are
paid for exports or what your solar system cost.
Because it only ever uses the current power and the current price, dynamic tariffs work out of the box: every second is priced at the price that held during that second.
Sign conventions
Every power sensor needs to say which way the power flows. Power Insight expects these signs:
| Device | Positive means | Negative means |
|---|---|---|
| Grid | buying from the grid | selling to the grid |
| PV system | producing | drawing power (inverter standby) |
| Battery | discharging | charging |
| Consumer | — | drawing power |
Most smart plugs report their draw as a positive number. If one of your sensors uses the opposite sign, turn on Invert power sign for that device. The unit doesn't matter: W, kW and MW are all converted.
Following the power
At any moment, power comes in from three kinds of source:
- the grid (what you buy),
- your PV systems (what they produce),
- your batteries (what they discharge).
It goes out to four places:
- home consumption: your appliances,
- batteries: charging,
- system standby: the idle draw of your energy equipment, such as an inverter at night,
- the grid: export.
What comes in always equals what goes out. Power Insight works out, for every source, how much of its power ends up in each destination. That is what the … to home consumption, … to grid and similar sensors show. The sensor reference explains how to read their names.
Example. The sun produces 3,000 W, the house uses 1,000 W and the battery charges at 1,500 W. The remaining 500 W go to the grid. The PV system's Production to home consumption reads 1,000 W, Production to batteries 1,500 W and Production to grid 500 W.
When a battery or consumer may only use specific sources, for example a battery that charges from solar only, Power Insight respects that when splitting the power. Where the power comes from explains the rules.
Putting a price on it
Once Power Insight knows where every watt comes from, it can price it. There are two ways to do that, and you choose which one you want in the options.
Standard uses your grid price. Power from the grid costs what you pay for it; power from your own solar and batteries counts as free. This answers the everyday question: how much is my solar saving me on my electricity bill?
Levelized also counts what your hardware cost. You enter what a device cost over its lifetime (purchase, installation, maintenance) and how much energy it will deliver over that lifetime. Dividing one by the other gives a price per kWh for your own power, the LCOE for solar or LCOS for a battery. This answers the investor's question: is my solar system actually paying off?
Example. Grid power costs 0.30 per kWh. Your solar system cost 12,000 and will produce 120,000 kWh over 25 years, so its LCOE is 0.10 per kWh. Every kWh of solar you use yourself saves 0.30 (Standard), or 0.20 once the hardware is paid for (Levelized).
Costs, savings and earnings
From those prices Power Insight builds a few kinds of money sensor:
| What it means | |
|---|---|
| Cost | What running something costs, such as your home, a consumer, or a battery's charging. |
| Avoided cost | What your own power kept off your grid bill. |
| Cost savings | Avoided cost minus what the device costs to run. |
| Export compensation | What you are paid for power you export. |
| Financial return | Cost savings plus export compensation: everything a device brings in. |
A battery's savings go negative while it charges from the grid: that energy costs money. They turn positive when it discharges and replaces grid power. Over a full cycle, the total is what counts.
Rates and totals
Money sensors come in pairs:
- A rate is money per hour, right now (
EUR/h), like a speedometer. - A total adds the rate up over time (
EUR), like an odometer. Totals survive restarts and work with Home Assistant's long-term statistics and utility meters.
If a power or price sensor becomes unavailable, the rates show unavailable rather than a wrong number, and the totals pause until it comes back. Power Insight never guesses.
Already have years of history in your inverter's app? You can carry it over so your totals start where your system really is.
Going deeper
- Costs, savings and the maths: the formulas behind the cost and savings sensors, LCOE and LCOS, and what happens when you change a device's lifetime values.
- Where the power comes from: the four flow channels, ratio vs. share, and how a battery's or consumer's source mix is decided.
- Carried-over history: bringing your existing totals into Power Insight.
- Glossary: every term on one page.
- Reference cases: worked example homes with flow diagrams.