QQ is a software that runs continuously, so it needs to be connected to the network all the time, which of course consumes a lot of power. There is no solution.

you can chat with others on wechat, which contains QQ offline message plug-ins. You can show that you are using WeChat when your QQ is offline, and you can receive or send it. It is very convenient and saves electricity. It doesn't consume much power to open WeChat 24 hours a day.