What is it? A portable, solar-powered device you can use to charge your gadgets.

How does it work? The sun charges the battery inside, which, in turn, can be used to power up your mobile phone, digital camera, games player, iPod or GPS unit. It comes with a selection of connectors, compatible with most brands, including Samsung, Nokia and Motorola. An additional connector is required for iPods. It takes about 10 hours to fully charge the device, but a few minutes are enough to get your phone working. You can recharge it from your laptop when you’re out of the sun, and the rechargeable battery inside stores energy for up to a year.

How green is it? It will save some electricity — but make sure you recycle your old chargers if you want to help the environment.

How much could it save me? Not very much, to be honest — it’s more about convenience.

How much does it cost? £49.95 from the Big Green Shop. It comes in black, white, pink and silver.

Is it worth it? It’s useful for camping and for taking on holiday, as it saves you packing several different chargers as well as an adaptor — a definite plus while we wait for the phone manufacturers to make good on last week’s pledge to come up with a universal charger.

Where can I get one? The Big Green Shop (0800 999 2134, biggreenshop.co.uk) or Solio (020 7424 7999, solio.com).

- Referring to your column on the loo water saver (June 28) — why pay for a Hippo, when you can just put one or two bricks in the cistern instead? How simple is that?

Dr Ken Webb, by e-mail

Could papier-mâché be a green alternative to plastic for making milk bottles? Do you have any green tips?

Or have you used a product featured in this column? Tell us at greenhouse@sunday-times.co.uk

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