The product that you buy for $2 has only level 3, that is, one stage. 

Don't misunderstand that there are three levels like me.

Anyway, based on my enjoyable experience... Level 3 Strategy:

For main power

1. Choose wind power: Look at the graph carefully. 

When power decreases, you should not increase building connections. Wind power can be installed up to 15 plants.

2. Choose solar + hydrogen battery: In this case, the battery is charged during the day and used at night. 

You need to watch whether the battery is sufficiently supplying the insufficient electricity supply. You can purchase up to 15 solar panels and 3 batteries.

About auxiliary power

- For coal power plants, keep all three power sources on throughout the game.

- For biomass power plants, if you only turn on one power button, you can continue to use them without worrying about running out of fuel. You can take advantage of this early in the game to get 6 free power.

- For hydro power plants, the combination of [5+5-3-3] does not run out of water. The combination of [5+5+5-3-3-3] will decrease the water level very little by little.

And...

I wish there was a speed multiplier shortcut or an automatic coal purchase button.

It was a long time ago since the last update, but it's too bad of a game system to disappear like this.