Glossary
The terms that keep coming up, in plain words. Each one with the reason it matters.
43 terms
No matching term. If you're missing one, feel free to say so in the comments.
B
- Base load
What the house uses without the big controllable consumers such as the heat pump. It's the baseline every surplus is measured against.
- Battery management system BMS
The electronics inside each battery pack. It protects the cells and can forbid charging or discharging. When it says no, everyone listens.
- Battery monitor (shunt)
A measuring device in the battery cable that counts every amp going in and out. Counting beats estimating, which is why its state of charge is the one the system steers by.
- Battery price
The average price of one kilowatt hour in the battery: solar at zero, grid charges at what they cost, weighted by amount. Taking energy out doesn't change it.
- Bisection
A search method that halves the range again and again until the answer is precise enough. Like guessing a number between 1 and 100 with seven questions.
- Bivalent heating
Two heat sources in one house that take turns, such as a heat pump and a gas boiler. The interesting part is deciding who's on duty.
C
- Coefficient of performance COP
How many kilowatt hours of heat a heat pump makes from one kilowatt hour of electricity. A COP of 3 means: 1 kWh in, 3 kWh of heat out. It changes a lot with the weather and the flow temperature.
- Curtailment
The inverter turns the solar panels down because the battery is full and nobody needs the power. The sun keeps shining; the energy is simply lost.
D
- Day-ahead price
The wholesale price for each quarter hour of the next day, set in a daily auction. Tomorrow's prices arrive in the early afternoon, so a house never sees more than about a day and a half ahead.
- Dead man's switch
An automatic fallback that kicks in when a sender goes quiet. One important detail: it must not run on the same computer that has just failed.
- Dynamic tariff
An electricity tariff whose price follows the wholesale market and can change every 15 minutes. The opposite is a fixed tariff, where every kilowatt hour costs the same.
F
- Fail-closed / fail-open
What happens when something is unclear. Fail-closed: when in doubt, locked. Fail-open: when in doubt, allowed. For anything that switches real hardware, the answer should be fail-closed.
- Feed-in
Selling solar power into the grid. Where it is paid, the payment you give up by storing energy is a real price in the battery account. Without a feed-in payment, solar stays at zero in the account.
- Fixed tariff
An electricity tariff in which every kilowatt hour costs the same, day and night. Simple and predictable, and there is little to optimise on the grid side.
- Flexible load
A consumer that can run whenever it suits the system, not whenever someone presses a button. In my house, that's crypto miners, which turn surplus electricity into computing work.
- Flight recorder
A complete log of every decision and every command, including who sent it. When something strange happens, you can find out who did what, and when.
- Flow and return temperature
The flow is the warm water going out to the radiators or the underfloor heating; the return is the cooler water coming back. The flow temperature is the main lever of any heating system.
- Forecast duel
Two forecasts compete, and only the better one gets to steer. A correction has to prove every day that it actually improves things.
- Freshness (age of a value)
How long ago a value was measured. After a certain time it counts as unknown. Not as zero, and not as “probably still the same”.
- Full hour (cell balancing)
Once a day, the battery stays at 100 % for an hour so the cells can even out. In my system, this is the one rule everything else has to fit around.
G
- Gate
A condition that decides whether a measurement may count or an action may happen. Too wide, and rubbish gets through. Too narrow, and nothing does.
- Grid charging / arbitrage
Charging the battery from the grid while electricity is cheap, to use it later when it's expensive. A good idea in moderation. Filling up just because it's cheap is not a plan.
H
- Heat price
What one kilowatt hour of heat costs. For a heat pump it is the electricity price divided by the COP; for gas it is the gas price per kilowatt hour of heat.
- Heating curve
The rule that says which flow temperature goes with which outdoor temperature: the colder it is outside, the warmer the water. Mine is learned rather than set once and forgotten.
- Heating limit
The outdoor temperature above which the house doesn't need any heating at all.
- Hysteresis / dead band
A gap between the switch-on and the switch-off threshold. Without it, anything hovering near a limit flips on and off like a nervous light switch.
I
- IPO principle
Input → process → output. The basic pattern of every decision in the house: something is measured, something is calculated, something is done. The logic map is laid out along it, from left to right.
K
- Kilowatt hour kWh
The unit for energy. A 1,000-watt heater running for one hour uses one kilowatt hour. Prices, battery contents and heat are all counted in it.
L
- Learner
A building block that estimates a relationship from measurements and keeps adjusting it. For example: how warm does the flow need to be at minus five degrees?
- Legionella protection
Heating the hot water to at least 60 °C at regular intervals, so that bacteria don't stand a chance.
- Linear optimisation LP
A mathematical method that finds the cheapest plan within fixed limits. Powerful, but only as good as the numbers you feed it.
M
- Median
The middle value of a sorted list. Unlike the average, a single wild outlier barely moves it.
- Minimum state of charge Min SOC
The charge level the battery should never drop below. It's the reserve for surprises: a cloudy week, a cold night, a forecast that was too optimistic.
- Modbus
An old, simple industrial protocol that lets software read values from devices and send them commands. Simple, but not unlimited: ask too much, too often, and some devices simply give up.
P
- Performance map
A table that returns the right value for a combination of conditions. The COP map, for example, knows the COP for each pair of outdoor and flow temperature.
- Planned discharge (drain)
Emptying the battery on purpose overnight to make room for tomorrow's sun. How far it may go is a calculation, not a gut feeling.
S
- SG Ready
A simple signal input on many heat pumps. Through it, an energy manager can say “power is cheap right now” or “please hold back for a while”.
- Shadow mode
A new building block calculates and logs everything, but doesn't switch anything yet. First it proves itself, then it gets responsibility.
- Short cycling
The compressor of a heat pump switching on and off too often. It costs efficiency and shortens the machine's life.
- State of charge SOC
How full the battery is, in percent. Sounds trivial. Getting a number you can actually rely on is surprisingly hard.
T
- Temperature spread ΔT
The difference between flow and return temperature. A heat pump needs a certain minimum spread. If it gets too small, the machine starts making decisions of its own.
- Thermal inertia
A heated concrete floor stores warmth for hours, so the heating reacts slowly. That's why adjusting it every few minutes achieves nothing, apart from confusing it.
- Tipping point
The electricity price at which the heat pump stops being cheaper than gas: gas heat price times COP. Below it the heat pump wins, above it gas does.
Your experience counts
Which system runs in your house, and where does it get stuck? I'd like to hear about your experiences, your doubts and your ideas, in the comments under the videos. Good ideas get picked up and built in public: as a video of their own or as an addition to an existing one.
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