Solar & battery
Solar and a home battery — why bills can still feel high
You invested in panels and storage to bring bills down. Sometimes it works brilliantly. Sometimes the numbers on the bill don't match what you expected — even when the installer said you'd be "mostly self-powered."
We've lived with solar and a home battery (on a time-of-use tariff) and talked to plenty of households in the same boat. The kit is usually fine. The gap is almost always timing — when power is made, stored, used and exported — not whether the panels are broken.
What the bill doesn't tell you on its own
Many people on older Feed-in Tariff setups only look at the quarterly statement and whether export payments arrived. That's understandable — the apps are often awful. But on modern SEG + battery systems, the bill is a blunt instrument:
- Import — what you bought from the grid (and when, on ToU tariffs)
- Export — what you sent out (and what you were paid for it)
- Self-consumption — solar you used at home (often invisible on the bill)
A bill can look "high" while solar is doing a lot of heavy lifting, because winter import, standing charges and a spike of evening use swamp the good months.
Four common reasons savings feel disappointing
- Battery timing vs your tariff. Discharging at 6pm when import is expensive helps. Discharging at 2pm when solar is already covering load doesn't. Many battery apps use generic "self-consumption" modes that don't know your Octopus window.
- Export when you'd rather store. On a good solar day the battery fills and excess goes to the grid. If your SEG rate is low, that can feel like wasted sunshine compared with saving it for evening.
- Winter reality. Panels produce less; heating and lights run more. Batteries help but don't magic away December. Comparing July and January on the same bill is a common source of "it's not working" panic.
- Only checking the supplier app. Tesla, Sigenergy, GivEnergy, SolarEdge — each shows a slice of the picture. The supplier app shows import/export at the meter, not what the battery decided to do internally.
One useful exercise: On a sunny day, note whether the battery fills before sunset and whether you're importing after dark. You don't need spreadsheets — just "did we coast through evening on stored solar?" If not, timing is the lever, not more panels.
You don't need to become an energy nerd
Plenty of solar+battery owners set a discharge window once (e.g. 5:30–10pm) and otherwise ignore it. That works until you add an EV, switch to IOG, or the installer leaves you with three apps. The goal isn't another dashboard — it's bills that make sense without daily babysitting.
Common questions
Why isn't my solar battery saving me money?
Often the battery charges or discharges at the wrong times for your tariff, or you're only looking at the total bill rather than import vs export.
Should I export solar or store it in my battery?
Compare your SEG export rate with what you pay to import — and when you actually use power. On time-of-use tariffs, timing beats totals.
Do I need to watch my solar app every day?
No. Daily checking is usually a sign the automation doesn't match your routine, not that you're failing to "manage" it properly.
Want a second pair of eyes?
Tell us your tariff, battery brand and what the bill feels like compared to what you expected. We'll suggest what to check first — free, no obligation.