Keeping our evening electricity bills under control was the main reason I added a 5kw growatt 51.2V Battery to my rooftop solar system last spring.

Before that, I sent most of my solar power back to the grid during the day and then bought it back after dinner, when rates were highest. That felt especially wasteful in summer, with the air conditioner running until bedtime.

The installation itself was easier than I expected. My installer mounted the lithium battery in the garage beside the Growatt inverter, ran the communication cable, and configured a time-of-use schedule. We set it to charge from solar first, hold a reserve of twenty percent, and discharge during the evening peak window. I appreciated seeing the battery state of charge in the app rather than guessing whether it was actually working.

The biggest change appeared on ordinary cloudy weekdays. On a typical day, my panels produce around 18 kilowatt-hours. The house uses roughly 22, so the battery supplies much of the four-hour evening gap. My monthly bill dropped from about $186 to $112 in the first full month, despite similar usage. During sunnier months, I have seen bills near $70, mostly the connection fee. It is not a magic zero-bill system, but the peak-hour savings are very noticeable.

I did have one minor troubleshooting moment. After a firmware update, the battery stopped discharging at the scheduled time and sat at 100 percent. I power-cycled the inverter, checked the app settings, and discovered the update had reset the tariff schedule to default. Restoring my peak and off-peak periods fixed it immediately. Since then, the solar battery has been quiet and predictable, which is exactly what I wanted.

For my home, the 5kw capacity is a comfortable fit: it covers lights, refrigerators, internet, and regular evening cooking.