system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why can't we store renewable energy in batteries?

Everyone says the biggest problem with renewable energy is there's no way to store it, but the battery has been invented already?
gpt
We can but batteries are 1) expensive to produce but have good efficiency 2) cheap to produce but have poor efficiency 3) take up a lot of space that you need to store and maintain. 4) wear out over time and require replacing 

Ideally you only want to ever produce as much energy as you use. A coal factory can turn on and off at any given moment, changing its supply to meet the demand. In this respect, there are _no losses_. Compare that to solar energy. You generate energy during the day, but no one's using it. It has to get stored, then you use it at night. That's less efficient than making it as you need it. 

A good solution is hydroelectric. When power isn't being used, it can store energy by pumping water back up into the dam. But hydro is an expensive investment and not suitable everywhere. 

Alternatively, using renewable energies to supply the grid and then minimally using non-renewable energy when you don't have renewable energies going on. This seems to be adopted by a lot of places. You sell your energy to the grid from your solar panel if you're not using it, and then you buy it back at night, which offsets your cost or even earns you a profit.