Reporters need accuracy in units

First published: 10th September 2009

The main message of the article "Dirty reality behind solar power" (9th Sept), that alternative energy projects have environmental costs is good, but the message is spoiled by mis-use of units: a kilowatt (KW) is a unit of power, a kilowatt-hour (KWh) is a unit of energy. Comparing the energy required to produce a solar panel (enough to run a fridge for two decades) to the power output (a kilowatt, "enough to run a fridge for a day") is incorrect. The panel would (in good sunlight) produce a kilowatt-hour every hour, so, given eight hours of sunlight a day, over its 20 year lifespan, it would produce enough electricity to run the fridge for 160 years. Not such a bad deal... but that doesn't count the pollution produced during production.

Solar panel efficiency has improved considerably recently, this clearly indicates the need for more education funding, so that the scientists and engineers can continue to improve them, and so that the reporters understand the difference between power and energy and can facilitate informed public debate.