That's why we're pleased to note that a company called ReNu has just announced a solar panel that can be used to charge your iPhone or iPod, power the device's sound dock, or even keep your desk light shining sans mains power.

ENGADGET: ReNu solar panels announced for iPhone charger, sound dock, LED desk lamp

It would not have been the original detectors that were hard-wired into the system because they run on mains power.

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The process of switching to mains power may reveal some further damage, but staff will be on hand to repair any outstanding issues.

BBC: Arran power: 'Every property has electricity restored'

When designed to be portable, it must be able to function without mains power and have a built-in display of at least 7 inches in diagonal.

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Many power and telephone lines are knocked out, while burst water mains have deluged whole districts.

BBC: New Zealand earthquake: Rescuers work through night

But it is a particularly good idea for an electric car because mains electricity can be used if the car is still plugged in, thus conserving battery power.

ECONOMIST: Vehicle telemetry