Zero Net Energy - Energy Storage

The time when you need most energy is not when you can best generate it.

Energy storage is a big problem. The time when you are most able to generate energy (eg midday using PV panels) is when you have the least energy requirement. You want to generate power during the day and use it in the evening. That means you need energy storage.

Electricity company energy storage

You may in your area have an electricity company that is willing to buy the excess energy you produce. When you generate more than you need at any particular time of the day then your electricity meter runs backwards. At night when the sun isn't shining then your electricity meter will turn the normal way. Zero Net Energy equates to the meter on average being stationary. The electricity company is acting as an energy storage system for you.

Battery storage

Using RV style lead-acid batteries is a possible solution. Batteries are however fairly expensive and have a limited life.

Pumping water

If you live on a large sloped plot then you could use your generated electricity during the day to pump water from a pond at the bottom to a pond at the top and then run a micro-hydro generator in the evening to generate electricity. Unfortunately it is hard to make the various inefficiencies work out.