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Q8: I was told (quite a few years ago now) that the energy used to create solar power battery cells outweighed the benefits accrued over its lifetime. Is this correct?
Submitted by Julienne Leathart

A: The energy payback time for solar energy – the time needed to recover the energy invested in manufacturing the solar system – is now about four years. Within a decade it will be less than two years. This compares with a system lifetime of 30 years or more.

Gram for gram, an advanced solar cell has the same energy output over its lifetime as a nuclear fuel rod. Also the amount of energy put into mining for the components of solar cells is 100 times less than that put into uranium, taking all aspects of production into account.

– Professor Andrew Blakers, Director, Centre for Sustainable Energy Systems, Australian National University

A: It’s true that a significant amount of energy is used in manufacturing solar photovoltaic modules. But a lot of energy is also used in building hydro-electric dams, wind turbines, nuclear power stations and coal-fired power stations.

Solar photovoltaic panels have lives of 25 years or more and if installed optimally in a suitable climate, the energy payback period should be much less than the lifetime of the solar system. And the energy payback period is constantly reducing as the efficiencies of photovoltaic panels are increased and the amount of solar grade silicon used is decreased.

– David Harries, Director, Research Institute for Sustainable Energy

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