Solar-powered lights - recommendations please ??

[meow2222]

In terms of energy efficiency it makes no attempt to be efficient - but thats not the issue. Its the classic mistake of alt energy types to concentrate on energy efficiency when the real deal is actually financial efficiency.

The treegen has zero visibility, unlike all other wind collectors. It uses almost zero materials, needs no support structure, there are masses of natural collectors already in place, and it costs a few pence. How can you beat that?

Oh, one last plus point. Due to the weight on string mechanism its possible to connect a whole handful of trees up to one generator, which incidenitally will then run more or less continuously.

NT

[Adam Aglionby]

Naturally growing windmill , like it a lot.

Adam

[Adam Aglionby]

For the naysayers who say solar power is only good on the Equator , dont get much more north in the UK than northern tip of the Shetland Isles or more mission critical than a lighthouse , Northern Lighthouse Board have 121 solar powered lighthouses:

ones LED, bigger ones use 35W metal halide lamp not unrelated to car headlight lamp. Very big solar arrays and batteries though.

Type of solar panel make a difference as well, poly crystalline cheapest but only really works well under direct Sun, mono crystalline and amorphous will charge in cloudy conditions but cost more.

1W LED is fine if you want to illuminate the gates not just the house number, 1W LED run at less than 1W, 350mA, gets very efficient.

If it dosent need to be white, green LED is the most efficient colour , have an old Maplin LED solar light that dosent receive direct sun for 8 months of the year, fitted with 3 off 5mm LEDs was lit for couple of hours over Christmas day evening.

Adam

[dennis]

Which ius a killer as far as being green goes. It is a low maintenance reliable energy source they put in, not a green solution as doing the maths will demonstrate.

If the OP is going to use batteries and LEDs then as they run for ages from a couple of nicads I would do away with the charging bit and just charge them in the house from a mains charger.. you know it makes sense.

[Adam Aglionby]

Very true, embodied energy is probably quite lot higher than a 3 cylinder Lister, but a demonstration of the ability of PV arrays if you have the budget.

Run a 24V line in reasonably heavy 2 core, speaker cable is good, then tap off for path lights and gatepost lights as required. LED with appropriate drivers or resistors at each point, 24V usually means that V drop at currents involved is negligible up to few `00metres. Add dusk and PIR sensors to taste.

Adam

[meow2222]

I wondered about that, burying it just 4" deep using only a blade to push it under the grass, no other protection. But how long would it last? FWIW only one core needs to stay serviceable, the ground can be used as a return if necessary.

NT

[Jules]

I'd wondered before about running 12VDC everywhere - I've got all sorts of stuff I can usefully run off 12V (both lighting and equipment), and in theory it lends itself to easy battery supplementation using a bank of car batteries, rather than relying on the 'green' source being available 24x7.

24V might actually be better and still have handy "off the shelf" charging properties.

but,

a) I'm not sure how car batteries would fare for a moderate, constant load (given that car use is generally a short, high-current draw and then a charge cycle),

b) The transmission losses involved might just be too great for a low-voltage DC system to really be viable.

(obviously car/truck batteries would need to be outdoors, but we've got a spare shed tht's got some useful ventilation, so that'd do I think)

cheers

Jules

[meow2222]

I think all the points you raise are dealt ith fairly well on the uk.d-i-y wiki. This would be a good place to look:

voltage wiring lead acid battery cables backup power

I'd also suggest one other possibility. If you'll run the 12v system off mains normally, then an iron carbon battery might be a good option for you.

Btw theres no need to put lead acids outside.

NT

[Jules]

Not sure what I'll do as power input yet; solar's obviously a bit unlikely (it doesn't make much sense to go solar -> electricity -> motor

-> alternator -> batteries -> electricity ;)

There's some scope for a wind turbine* here, and I'm on the look-out for a diesel genny too (our water's from a private drilled well, so of course the pump doesn't work if the power goes out!)

• I don't really like the things, and certainly wouldn't buy a commercial one, but I think I can homebrew one and can get about 50' of height if I put it on the barn roof, so that might be just enough to do something vaguely useful.

Can't move for trees around here either, but I'm not sure if using them to raise steam and generate power that way is particularly sensible (although the wood's rather good for house heat!)

Hmm, I thought car batteries were prone to venting (potentially) nasty stuff - sealed lead-acids are another matter, of course.

cheers

Jules

[Adam Aglionby]

Probably less than ideal, deep cycle batteries are always a better bet and not ludicrously more expensive. Traction batteries on other hand....

24V is popular for that very reason, half the copper of 12V for a given load or double the load. Vehicle makers were very keen on changing everything over at one point.

For LED lighting makes wiring very simple with adequate headroom for voltage drop.

PVC insulated cable tends to survive the outdoors fine, especially buried out of the Sun , no UV, containment not really neccessary apart from perhaps mechanical protection in some areas.

Wouldn`t neccessarily need to be outdoors, lot of public buildings have cabinets full of the things somewhere for emergency lighting.

cheers

[Jules]

Yeah, I've not looked into cost yet. A quick google seems to indicate somewhere in the $90-$140 range for car batteries, which is probably about

60-100 quid or so. That's probably about what I remember them being in England, too.

I think I remember when my dad's old Beetle had 6V electrics... But yeah, I'd be as happy dealing with 24V as 12V I think.

Well out here in my area of USVille there's no building code (no building regs or planning permission) but there is an electrical code, and I know that specifies conduit for outdoor wiring. Of course they assume that's at domestic AC rates, not LV-DC, but I don't think they make the distinction. I'll have the check though, as it's possible that the rules only apply for things directly connected to the house fusebox - maybe if it's downstream of a transformer or off-grid altogether (e.g. solar) then I can do what I like.

change to see a battery-noly emergency setup (we had a diesel genset at one site, but of course that just needed a single truck battery for starting purposes, rather than a big bank).

That site still seems to say (I've only had a quick flick through so far) that ventilation's vital when charging car batteries due to the gases given off. Of course "how much is enough" is the vital question... maybe it's only an issue if you have the battery in a tiny box and go stick your head right in there :-)

cheers

Jules

[meow2222]

30Ah used car batts are a tenner here, though not very good for offgrid use. For deep cycle types you can always make your own.

Dont overlook the 3 wire system. May do a wiki article on it some time

Its only vital if enough hydrogen is given off to potentially reach explosive levels, and thats rarely the case.

NT

[Adam Aglionby]

Shopping around on batteries always pays off, like lamps can see quite some cost spread even on same brand, try looking for "leisure batteries"

6V electrics earned Joe Lucas , maker of 6V British bike electrics, the well desrved title as The Prince of Darkness.

Convoluted and variable are US Electrical codes , but would guess they mostly use a definition of Safety Extra Low Voltage, in Euroland below

50V, that should mean you can do pretty much what you like at 24V.

Think Malibu lights and IDC connectors;

remember that though voltage is low , available current can be quite high and put fuses in all the sensible places.

Its hydrogen build up thats the risk , but batteries that need to breathe have vent pipes that can be led to fresh air and regularly inspected.

Need a bit of care charging and maintaining multiple batteries, available current is , er, quite a lot, dead short will have several `000 amps run through it.

It isn`t rocket science but it is worth respecting having several litres of sulphuric acid sloshing about and enough current to vaporise copper tube...

Cheers

Adam

[Jules]

Will do...

Same Lucus of the car world? I've owned numerous Triumphs over the years with Lucas bits and they certainly weren't premium quality :-)

Yeah, I wasn't sure if a commercial system goes through extra testing which somehow certifies it whereas a DIY approach wouldn't - but I suppose that makes life messy, so it'd be far easier to declare anything under a given voltage as free from inspection.

Absolutely :-) I've seen the results of dead-shorts and overcharging in car batteries and it ain't pretty...

cheers

J.

[Andy Champ]

IIRC hydrogen will explode in air if it gets to 2% concentration. It shouldn't need an awful lot of ventilation to get rid of it though, it isn't going to do the butane trick of collecting in a pool in the corner.

Of course, if it is bubbling away and making gas you'll need to keep an eye on the fluid level and top up with distilled water as necessary.

Andy

[unopened]

Some people have used old Nickel-Iron (NiFe) batteries. They may not be commercially available now, but they seem to have a reputation of surviving abuse quite well. I have not used them myself, but filed their existence away as something to investigate when time allows.

Cheers,

Sid