ESS is it worth buying?

Portable Energy Storage from the Mercury family

Mercury family products are independent energy sources that operate without the need to be connected to the power grid. They have a capacity of 1.0 or 2 kWh. These are portable power banks for your devices that provide electricity anywhere and anytime. You can charge them from the power grid or with the help of renewable energy sources (e.g. solar panels), and then use them in places without access to electricity - during trips, camping, during renovation work and many others. How to use Mercury with a capacity of 2.2 kWh?