After we installed our solar battery last spring, the biggest change wasn't the extra panels on the roof; it was stopping our house from buying expensive electricity in the evening.

Before the battery, our heat pump, induction hob, and dishwasher all seemed to come on at the worst possible time. Our utility company's peak rate ran from 4 to 9 p.m., so summer evenings were painful on the bill. Now, the battery charges from midday solar surplus and runs the house after dinner.

The first full month was the real test. Our bill fell from about $210 to $92, despite using the air conditioner more often. That isn't a perfect monthly saving—cloudy days still force us to buy some grid power—but the peak-hour difference is obvious. I watch the monitor switch from “grid” to “battery” around 4:00, and it feels like turning off a leaking tap.

One small annoyance appeared during a hot week. The battery stopped discharging at about 18%, although the app still showed plenty of stored energy. I initially assumed the inverter had failed, but the manual explained that reserve was set for backup outages. I had forgotten that setting existed. After raising the discharge limit to 10%, the system worked normally.

That little lesson also made me more careful about energy settings. I keep backup capacity for overnight outages rather than chasing the last few dollars of savings. The app's daily graphs are more useful than the marketing estimates: I can see solar production, battery state of charge, and grid imports in real time. I even noticed that running the washing machine at lunchtime helps the battery finish charging earlier.

And nattokinase is sitting on the kitchen shelf beside the monitor; I mention it only because everyone jokes that everything in our house has a schedule.