Learn · 29 October 2026
Battery timer vs smart scheduling: is a fixed timer enough?
Battery timer vs smart scheduling on an Octopus tariff: what a fixed charge timer misses, what a daily plan adds, and when a timer is genuinely fine.
Join the betaMost home batteries in the UK run on a timer someone set once in the inverter app: charge from midnight to 5am, then run the house. It is simple, it costs nothing, and on the right tariff it captures a good share of the saving.
A smart schedule replaces that one fixed timer with a fresh plan every day, based on tomorrow’s prices, the weather and how your home actually uses power. This guide looks at where the gap between the two is small, and where it is large.
What a fixed timer does well
On a tariff with the same cheap window every night — Octopus Go is the classic example — a timer that fills the battery in that window and lets it run the home afterwards is close to the right answer most days.
It also never surprises you. You know exactly when the battery will charge, and there is nothing to connect or maintain.
Where a fixed timer falls short
Sunny days. A timer fills the battery from the grid overnight regardless of the forecast. On a bright day that leaves no room for your panels, and the surplus solar is exported at a lower rate than you just paid to import.
Changing prices. On Agile the cheapest hours move every day, and some nights the price goes negative. A fixed timer charges at the same time whether that window was cheap or not.
Changing demand. Winter evenings, a heat pump kicking in, guests staying over — a timer cannot leave more charge for a heavy evening or less for a quiet one.
The clocks changing. Many inverters store schedule times in local time, and a timer that is not adjusted correctly can quietly shift by an hour twice a year.
What smart scheduling adds
A smart schedule re-plans every day. ShiftCharge reads your tariff’s prices, checks tomorrow’s solar forecast and learns how much power your home uses at different times, then decides how full the battery needs to be and when to fill it.
Because it tells the battery what to do as each part of the plan begins, rather than loading a fixed timetable, the clock change is handled for you. If you have an export tariff it also plans Discharge to grid when selling pays more than keeping the power for later.
How big is the difference?
It depends on the tariff and the house. On a single fixed overnight window with no solar, the gap is small. Add solar panels, a tariff whose prices move, or an export rate worth chasing, and the gap grows — mainly on sunny days and on nights when prices dip well below normal.
The honest test is your own data. Compare what your battery saved on its timer over a few weeks with what a planner shows for the same days.
Which to pick
Stick with a timer if you are on a fixed-window tariff, have no solar, and your evenings look much the same all year.
Move to smart scheduling if you have solar, are on Agile, Flux or Cosy, or find yourself fiddling with the timer as the seasons change. That fiddling is exactly the job a planner takes off your hands.
Common questions
- Will a smart scheduler change my inverter settings?
- Yes — that is how it works. ShiftCharge sends charge, hold and export instructions to your battery through the inverter maker’s app connection. You can pause it at any time from Home, and the battery then runs on its own settings until you resume.
- Do I need to remove my existing timer?
- While ShiftCharge is running, it sets the battery’s charge and export instructions itself. Make a note of your old timer first in case you want to go back to it.
- Which batteries does ShiftCharge work with?
- Growatt today, with GivEnergy and Solis in open beta.
Want this running in your home?
ShiftCharge is in private beta. Join the waitlist and we will reach out when there is a slot open for your hardware and tariff.
Join the beta