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About this tool
Compare home battery charge and discharge scenarios against your tariffs and load profile.
A time-of-use battery simulator estimates how much a home battery saves by charging when electricity is cheap and discharging when it is expensive. Paste your tariff intervals as time | load kWh | price per kWh, set usable capacity, per-interval charge power and round-trip efficiency, and this tool charges the battery in the cheapest interval, discharges it into the highest-priced intervals first, and reports the difference against your unshifted baseline bill. It is a price-arbitrage illustration for comparing scenarios, not a control system or a quote.
Open Home Battery TOU Simulator on AltFTool — it loads instantly in your browser.
Paste your tariff into Load and price intervals, one row per interval in the form Time | load kWh | price per kWh — it opens with 00:00 | 1.0 | 5 through 22:00 | 1.2 | 6.
Set Usable battery capacity (kWh), Charge/discharge per interval (kWh) and Round-trip efficiency (%), which default to 8, 3 and 90, or load the Four tariff intervals preset.
The headline reads N estimated savings with a Baseline … · simulated … caption and rows for Charge interval, Grid energy charged and Energy discharged, plus a Discharge time / Price / Battery kWh / Avoided cost table; Download saves home-battery-tou-simulator.txt.
Every interval takes its own price and load, so a three-band or four-band TOU schedule is entered as it actually reads on your bill.
Grid energy drawn to charge is grossed up by the round-trip efficiency, so the kWh you pay for is larger than the kWh you get back.
A table lists which interval the stored energy was spent in, at what price, and the cost each block avoided.
It charges once, in the lowest-priced interval you entered, then discharges into the remaining intervals in descending price order. Each interval takes the smallest of three limits — energy still stored, the per-interval charge/discharge figure, and that interval's own load — so the battery never exports more than the house is using.
It sets how much grid energy you must buy to store one usable kWh. At the 90% default, storing 2.7 kWh takes 3.0 kWh off the meter, so the 10% loss is billed at the cheap charging price and never comes back out at the peak price.
No. The model deliberately omits solar generation, export or feed-in tariffs, reserve state-of-charge, degradation, demand charges and any utility control scheme, and it treats each interval as one charge or discharge block rather than modelling its duration. Treat the output as a comparison between scenarios, not a payback calculation.
Per cycle of the intervals you entered. If your rows cover one 24-hour day, multiply by roughly 365 for an annual figure — but only if that day is typical, since summer and winter load profiles usually differ enough to change the answer materially.
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