What does energy payback time mean?

You need energy to make a solar panel. Put it on your roof and see how long it takes to generate that same amount of energy. That's the energy payback time.

Energy payback time means the length of time that a solar panel (or other device) will take to produce that same amount of energy that was used to make it.

This is used with renewable and non- renewable energy solutions to describe how long it takes for the device to generate the amount of energy that it took to make it in the first place. It can also be used to measure the amount of energy your save by using an energy efficient device.

payback time = total costs/ total saving or money made or energy produced per year. You can thing of payback time in both economic and energy terms - how long it takes to pay back in money terms the costs, or thinking about the costs being the energy needed to produce the device.

A wind turbine's energy payback time is about four months. The estimated life of a wind turbine is about 25 years.

Devices like:

• solar panels
• wind turbines
• water turbines
• geothermal power plants
• biofuel plants
• biomass power plants
• wave and tide power plants