cheap solar backup power

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cheap solar backup power

Postby floydster » Wed Jul 30, 2008 10:39 pm

Currently on offer from Maplin: ... 5&DOY=30m7

Looks pretty good for a panel, controller, battery and a couple of LED lights.

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Postby dargles » Thu Aug 07, 2008 7:43 am

Wow - only just discovered the home energy bit of this forum!

I've started to convert my car lighting to LEDs, and they're fine, no problems. I've also persuaded my wife to let me try and see if we could light a single room at home with LEDs - now I have to make it work! Reading around, it seems the key issues are that it's hard to get a natural-looking light from LEDs, and that you would need a huge number of LEDs to get a decent amount of light. Also there's the directionality bit as well, but if one needs a huge number of LEDs, I can't see that's a problem.

Has anyone tried home lighting with LEDs? What are the key issues? I'm tempted to get the Maplin set-up and have a play, but suspect I'd need rather a lot of them to light even one room sensibly?

Regards, David

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Postby qdos » Thu Aug 07, 2008 8:22 am

Interestingly enough there was a Grand Design prog on the other day where they had used lots of lights and half of them were LEDs which seems to be a way of getting best of both worlds.

Re LEDs on cars. Very few LED bulbs are legal I would be very interested to know if you have found some legal E Marked ones as I would like to use some too

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Postby microman » Thu Aug 07, 2008 11:23 am


I've been experimenting with LED lighting for some time and am rather disappointed to date. The directionality means they are best suited to spots and I have both multi- and single-LED GU10 types in a stairway which for safety reasons is lit almost continuously.

The multiple LED versions tend to have rather low light levels and lose the odd LED or two over time. The single LED (3, 4 or 5W) are quite impressive when they work. But the QC tends to be abysmal - they are of course Chinese. Mostly its the 230V to low voltage converter that blows up - sometimes spectacularly. The latest batch of 5 I have from UltraLEDs have had one failure after a few hours, the rest are OK. Failure often occurs at initial switch-on, so you might find them even less reliable in a more usual application.

Colour rendering is a matter of taste as with CFLs. If you like the yellow light from incandescents you won't like the more efficient 'cool white' ones. (Actually its hot white being more blue but then I can be a pedant). The warm white are less effcient but most people prefer them.

I would suggest going to a specialist LED supplier rather than Maplin.

Summary: good for energy saving - bad for overall economics.


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Postby NickJ » Thu Aug 07, 2008 2:43 pm

I have been very impressed with the osram range of LED lamps for architectural lighting ( ... W3854.html) . I have used these for several projects and they are reliable and easy to use. You must use the special driver unit, bu that is as easy to use as any halogen transformer. I do agree there are some terrible LED lamps out there which are not worth the money. IF you want to use LED you have to pay the money at present, a bit like using Li batteries in an EV!

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Postby dargles » Thu Aug 07, 2008 4:03 pm

Hi, guys, thanks for the replies.

Uh, in order...
1) LEDs in cars - my son bought me the first two, stop & tails, and he's normally fairly careful about such things when he does his research. I'll check. However, I can say that they are as bright, if not brighter than the incandescents, and seem to have a good angle of viewing. I gather they weren't cheap though (bought as a birthday present for me). One other thought - I'm using them in my Gentry, my son fitted them to his MX5; they haven't got to be too good to be better than the originals... :wink:

2) 230V-low voltage converter - I would not be averse to installing an alternative low voltage (e.g. 12V) wiring circuit in the home. Doubtless some EU bureaucrat would tell me I can't do this :evil: . On the other hand, it might just give me the opportunity to bypass 20 other inconvenient EU regs... :twisted:

3) Colour - my feeling here is that the important bit is to get something working on a small scale, and then see if I can find a way to make improvements and then go wider scale.

4) Economics - I could be persuaded to go LEDs just to save energy, except the thought of spending £20K on solar panels for example to save 20p a month for the next 40 trillion years does seem a little senseless... (OK, I'm exaggerating, but you know what I mean - there's a limit, and spending vast sums in this case on LEDs doesn't appeal) Er, let's try and rephrase that. What I mean is that I'm sure I won't get a "payback" on LEDs in the car for example, but it's cheap enough (just about...) for me to feel good about going that route.

5) I'll have a look at the Osram range - thanks.

OK, need to get to the post office before it closes - thanks guys, I'll see where this gets me to.
Regards, David

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Postby dargles » Thu Aug 07, 2008 6:42 pm

Hi, Qdos.
Haven't got a reply from my son yet, but did have a look on a legal forum re LEDs on cars. The more I look, the more confused the picture seems. The key points seemed to be:
1) The law is way behind where we're at (so what's new...)
2) The law specifies watts, not lumens, so a LED bulb will fail on that basis by definition. Unless someone comes up with a "watts equivalent rating" or something stupid.
3) Someone reckoned that the police are unlikely to care so long as "it's bright enough". That certainly goes with my experience of years ago, but isn't reassuring because:-
4) ...the crunch is likely to come in an accident when the delightful insurance companies will have a ball if they think they can get out of paying because you've used LEDs (no, really, I love insurance companies... not... :evil: )
5) There's a whole load of folk-lore out there about what is and isn't legal, most of it incorrect.
6) Fancy a test case... :) ?
7) Older cars didn't meet the legal requirements for wattage, so there's a get-out clause that says something like, "so long as there's enough light produced"... But this applies to any car apparently. It's just that no-one's sufficiently confident on how this one applies in practice, so it's back to 6...

None of that answers the E-rating issue. My feeling is that, so long as the car looks legal (i.e. doesn't dazzle in one direction, is bright enough, has a decent angle of spread) then I'm not going to worry until a policeman pulls me over to ask hard questions - which I don't think is going to happen.

In any case, it seems to me crazy to look too hard at car lights when bike lights are in practice totally unregulated. Some are fine, but far too many are too bright in one direction, are directed upwards to eye level, and flash (which I don't believe was ever made legal) in a way that totally confuses pedestrians and drivers as to how far away they are (a bit of maritime experience would help here...)

Regards, David

PS: Now been in touch with my son. The coloured lights aren't a problem in practice, but the whites are. He failed his MoT because the front whites were "the wrong colour". Now that's interesting, because the blue tint that he had was exactly the same as on the standard Audi kit. There's also some discussion about "warm whites" an the fact that this can sometimes mean purple. It's the whites I need to do next - my inclination is to try it and see - there's every chance that it won't really notice behind my old, discoloured lenses... -David

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Postby ChrisB » Mon Sep 22, 2008 8:07 pm

This weekend I made a superb purchase 8)

How about 120watt Sharp PV panel for a just £235 8)

Wow its not until you buy a decent sized panel you start to realise how much power there is out there to be had, had it out in the sun over the weekend and checked the open circuit voltage and found about 21V so loaded it with a 12v 60watt bulb thinking that will make it grunt and expected the load would pull the open circuit voltage down to a more reasonable 15 or so volts.............................pop went the bulb :roll: :lol:

Right so it wipes out 12v 60watt headlamp bulbs with ease then :oops: well I should have realised :oops: just wasnt thinking I suppose.

Next test was to wire up both sections of a head light bulb giving me 115w load, hooked it up and it shone like a good'en 8) with a loaded voltage of around 12.3 volts.

Defo need some sort of reg on this beasty panel, any suggestions , really dont like the idea of forking out for a 60+ quid reg that shops flog, there cant be much inside these little boxes apart from a few components ?

I reject reality and substitute my own !!!!!!

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Postby retepsnikrep » Tue Sep 23, 2008 2:55 am

ChrisB wrote:This weekend I made a superb purchase 8)

How about 120watt Sharp PV panel for a just £235 8) ChrisB

Where? Any more?

Back to the solar controller, I'm a big fan of Picaxe chips now for obvious reasons, and there is a thread running about such a solar controller project, so why not build one yourself :wink:
Regards Peter

Two MK1 Honda Insight's. One running 20ah A123 Lithium pack. One 8ah BetterBattery Nimh pack.
One HCH1 Civic Hybrid running 60ah A123 Lithium pack.

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Postby JonSpence » Tue Sep 23, 2008 8:04 am

ChrisB wrote:Defo need some sort of reg on this beasty panel, any suggestions , really dont like the idea of forking out for a 60+ quid reg that shops flog, there cant be much inside these little boxes apart from a few components ?


There is now. What use to be done was that a dump load was applied to regulate the voltage and that voltage either used directly or inverted.

What's now done, in the inverter or charge controler, is something called maximum power point tracking. ... nt_tracker

Here is a DIY design from 98 to get you started. ... cleID=6262

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