Scargill – the Continuing Solar Lamp Experiment and the B&Q specials

garden lightsI’ve spent quite a bit of time now collecting information on solar lamps – it’s become something of a hobby – and I’ve come to a conclusion – most of them are not worth a light – as it were!

The lights you see in the image are part of a testbed I ran last winter – and now the sun’s out their getting a good test. Why buy in the winter? To see how they stand up to the weather of course – and some don’t stand up AT ALL.

The far distant lamps you see are fairly typical of the £25-a-pack-of-10 types from B&Q and elsewhere (these came from a shop in Southern France, others from B&Q) and I’ve tried many other types – the reason you don’t see them all here is they’re in the bin. Almost to the last man the cheaper ones with plastic tops degrade very quickly and become frosty – all but stopping the light getting through. Given that in winter we don’t really have enough light to charge these lamps anyway that’s really not acceptable. I’ve just been outside now with a brillo pad cleaning up some which had gone completely white.

The lamps at the rear in fact have resin covers and up to now a year after buying them – they looked as good as new – but 6 months later – the white powdery look was getting them as well.

Now, take a look at the lamps at the front. You’ll notice they are hinged (and the solar cells have a thin piece of what appears to be glass in front of them – and none so far have shown any sign of ageing) and so you can direct the light anywhere you want – and they are a floodlamp which means the light is focussed in one direction, while pointing the solar cell to be exactly pointing to where the sun will be at mid-day.

Typically, solar lamps find themselves along the edge of driveways supposedly lighting up the driveway – well in practice they end up lighting up the grass, the sky -just about anywhere except where you ideally want the light and all from one, white pathetically underpowered LED, there simply isn’t enough light to go around – oh sure, they LOOK bright when you look at them – but that’s not what you want- you don’t WANT them firing light at you – you want them firing light at the driveway or whatever – and that’s just what these newer spotlamps do – from 3 leds, one one. Looking at my gravel path there, 4 or 5 of those lights adequately light up the gravel – on the other hand NO number of the more traditional designs would do this. In Spain, with superior sunlight, there is really no need to use anything other than lamps like these.

So with positionable solar cells, even on a modestly sunny day in winter (as long as there is SOME sun) these floodlights work well – in summer they work amazingly well.. and despite trying two different types – firstly a pair from B&Q and secondly a set from PoundStretcher (around half the cost of the B&Q types but only available when it suits them) these work absolutely marvelously – and the solar cells used look like some kind of modern thin-film jobs – they look nothing like the little strands of silver and blue you normally get with these lamps – the latter ALSO tend to change colour and start to look ill with time.

The units operate incidentally on 2 AA rechargeable and it’s good to see that many manufacturers are now using NIHI batteries as against the totally useless NICADS often found in the very cheapest units. The voltage to drive the white leds comes from a little circuit called a Colpitts oscillator – basically a couple of transistors and a coil to bump the voltage up a little – as white leds need nearer 5 volts than the 2.4v given out by the 2 batteries in series. Such circuits are also used to save on batteries with some manufacturers reducing the circuit down to one battery – that’s to their benefit – not yours.

So, if you’re planning on garden solar lighting – I hope this is useful to you. I’ve taken a boatload over to Spain with me to light up the top of our little mountain – more on our next trip in a week.

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