Terms, explained simply
Quotations are full of words that look alike and mean different things. Below, each term appears first in one sentence and then in a little more detail.
EMS: energy management system
The layer that decides which device gets energy when.
An EMS measures what is happening, predicts what is coming and controls accordingly: battery, water heater, heat pump, charge point. It is not a device but a decision layer above the devices already installed.
ESS: Energy Storage System
Battery and inverter working together for self-consumption and grid interaction.
An ESS makes sure your battery charges on solar surplus and discharges when you consume. It does not control your other devices. Almost every offer contains an ESS; that is layer 4.
BMS: battery management system
The protection that looks after the cells.
The BMS watches the voltage, current and temperature of each cell and limits charging and discharging. It sits inside the battery and makes no decisions about your consumption.
kW and kWh
kW is how hard, kWh is how much.
A tap opened wide delivers many litres per minute, that is kW. How much ends up in the bucket is kWh. A battery has both: a power rating in kW saying how fast it can deliver, and a capacity in kWh saying for how long.
Capacity tariff
You pay for your heaviest quarter-hour, not only for your consumption.
The grid operator measures how much power you draw in each quarter of an hour. The highest value of the month is your monthly peak; the average of twelve monthly peaks sets part of your bill, with a minimum per month. Export does not count.
Peak shaving
The battery steps in at the moment your peak is forming.
Instead of drawing everything from the grid when several devices run at once, the battery supplies the difference. For that, something has to see the peak coming in time; that is the job of the EMS.
Quarter-hour data
Your consumption per quarter of an hour, measured by the digital meter.
You can download these figures from your grid operator's portal. They show your real profile: when you consume, how high your peaks are and how often they occur. We would rather size on that data than on an annual average.
Self-consumption
The share of your solar energy that you use yourself.
What you use yourself, you do not have to buy. What you export earns a rate far below the purchase price. Raising self-consumption is therefore usually the first gain.
Single-phase and three-phase
One or three live conductors into your building.
A three-phase connection spreads power across three phases. That affects the choice of inverter and battery, and whether a device on one phase can cause your peak. Both are possible; the approach differs.
Backup
Pre-selected circuits keep running during an outage.
Not your whole home, but what you choose in advance: lighting, fridge, internet, heating. Switching over takes a moment, unless true UPS operation has been designed in. Which circuits come along is a design choice with cost consequences.
Off-grid
Running entirely without the grid.
Technically possible, but it needs far more storage and production than people expect, plus a plan for dark winter weeks. We do this after a feasibility study, never as a package.
Dynamic tariff
An electricity price that differs by the hour.
On a dynamic contract you pay a different price each hour, which is sometimes even negative. Shifting consumption to cheap hours then earns money, but only if something does that automatically, within the comfort limits you set.
Cascade or surplus control
The order in which your surplus is used.
Household consumption first, then the battery, then hot water, then climate, then the car, and only then the grid. That order is a design choice and determines a large part of the return.
Thermographic check
A thermal image of the connections before handover.
A poorly tightened terminal gets warm before it fails. A thermal camera shows that while the installation runs under load. We do this check as standard at every handover.
Open protocols
Connections that do not depend on a single brand.
Modbus, MQTT and documented APIs let devices work together that do not know each other. That keeps you out of a single ecosystem and lets your installation grow later with brands that do not exist yet.
A term you do not find here?
Send it over. We will explain it in plain language and add it if others would benefit too.