Solar panel with mains plug

[the.fee.fairy]

I'm still looking for these fairy lights!

I could compromise...a solar panel that has a mains plug on it - so that i can get some garden lights and plug them into the panel. hope that makes sense!
There are a few places to get low-energy garden lights. I've been reading a bit on solar panels, and i reckon a small one would run a set of these lights. But i need a mains plugpoint.

Got to able to be waterproofed somehow, even if its a wre coming from the solar panel that i can put in a waterproof box with the lights plugged into it.

Oh..and not overly expensive either!! I'm not rich!

Suggestions please! Ta

[contadino]

You would need a battery (car or van battery would do but better using a leisure battery from a caravan shop), otherwise the lights would only work when it was sunny. I think you should start looking for some 12 volt lights. Connect the solar panel to the battery (probably best putting a charge controller between the two - approx £9). Then connect the lights to the battery.

[Muddypause]

I may have missed reading your plans, Fee - are you planning mains voltage fairylights in your garden? If so, officialdom would now have it that you must employ a fully certified government agent to install them. Ordinary people can no longer deal with mains voltages in the garden, bathroom or kitchen beyond changing a lightbulb. It's for our own good, y'know, and we really ought to be very grateful for those H&S bods for spotting this before something nasty happened.

On the other hand, you can, like many people, use a bit of common sense, ask around when there is stuff you don't understand, and ignore those meddling people in suits who wouldn't know a blue wire from a brown one.

Of course, I haven't actually told you that, you understand?

So, my first question is, do you mean a solar panel with a mains socket on it, rather than a mains plug? Do you simply want to plug the lights straight in to the panel, or am I misunderstanding? I suspect, in any case, that mains voltage PV panels are not usual - low voltage rules, so to get mains voltage, you'd need an inverter. And a battery. But all this may make your plans impractical and expensive. Low voltage fairylights would be the way forward.

You'd need to keep the battery and all the connections sheltered (in the shed? In a box under the PV panel?) and simply have a long wire (not too long) leading to the lights. If you want to bury the wire, run it through some conduit first (a bit of old hoespipe would be good enough for low voltage stuff).

[the.fee.fairy]

The second option muddy. i just couldn't think of what a socket was called when i wrote the message...

I want to have fairy lights that are powered by solar. I don't want to have mains wires anywhere near the garden.

I saw these lights on Ebay - solar powered fairy lights for the garden, and they'll be perfect!! i want t bury the wire in the edge of the beds and thread the lights up into the bottles, so that when it gets dark, there are little lights shining in the bottle edging! So...i don't want to use mains power, because that seems like a bad plan. Solar is the way to go.

So...back to the lights on Ebay: They're bloody expensive!! So i was thinking about the solar power option and getting a panel with a socket in it so that i could plug in some fairy lights. Low power ones are quite easy to get hold of, but i'm not sure whether they have converters in them - they're meant to be plugged into the mains.

However...in Focus today, i picked up a catalogue and they had....solar fairy lights! £14.99 a set. They've not got any in that store, and they're not online, but the lady said i could order some.

now...back to the solar panel thing. If i got one, would it be possible to attach it to more than one socket? So i could get a few strings going?

Hope thats a bit more clear!

[Martin]

you have an intrinsic problem..........a solar panel only works when the sun's shining, and you want to have your fairy lights at night...........so somewhere along the line you have to have a means of storing the power (a battery - for which you'll need a charge controller)
The little individual garden solar lights have it all in one case - typically a small solar panel, feeding a couple of nicad batteries - and a sensor that detects nightfall, and turns them on in the evening. They are ridiculously good value for money, and are probably the cheapest way to go - just get loads of them!

[the.fee.fairy]

i looked at them and the problem is that they won't fit into the neck of a wine bottle.

If i put loads of the standing lights in the garden, then the dog with 'dig' them up and bring them to me. And, i think it'll look prettier with the lights in the bottles in the edging, it'll look a bit magical because you won't be able to see them during the day, only when it gets dark.

That's why i specifically want fairy lights - the little white LED ones preferably.

[Martin]

you could plant the base unit in the flowerbed, and extend the cable to the led (carefully remove the led, and extend the cable), and mount that in a bottle!

[the.fee.fairy]

from a stakey one?

how many LEDS are in them?
i thought the fairy strings would be easier - they're already strung together and they've got some space between the lights.

[Muddypause]

Are you up for a bit of DIY? If so, get a solar panel + battery + charge regulator - maybe get a ready made solar charger + battery. This will be your power supply unit. From here you can attach whatever you like (obviously limited to battery and PV capacity).

Then get as many LEDs as you like in whatever colours you like from somewhere like Maplins. Easiest to get some rated for voltages suitable for your PSU, and then link them all together with wire (whatever lengths suit) using a soldering iron, or terminal blocks, or whatever. This way, you'll be getting what you want, rather than trying to make someone else's idea fit into your scheme. However, be aware that white LEDs are fairly new things, and still seem to be comparatively expensive (eg. red, green or yellow = 50p, white = £3.00)

If you need more instructions, I'm sure between us we'll be able to guide you.

[the.fee.fairy]

Thanks Muddy!

So...many many questions to follow:

I'm not an electrician by any stretch of the imagination, so please bear with me!!

1. Is there a limit to how many LEDs you can get running from one solar panel? If so, how do i calculate this?

2. how do i waterproof it all?

I'm thinking i'll probably need the brightest ones possible because of the green glass in the bottles, and the fact that the bottles are likely to get grimy.

3. Any idea how to stop the bottles getting dirty inside? I don't particularly want to have to take the bottles up every few months or so to clean them.

4. Do LEDs heat up a lot? From my understanding, they don't get as hot as normal lightbulbs, which is why they seem like a better idea for going inside bottles so that the glass doesn't break.

5. following on from that - are the bottles likely to break? if so, what's the best way to prevent it?

There are many reasons why i love these forums! And this is one of them - there are people out there that have great brains that i can pick without seeming like an idiot...and people who know how to make dreams reality!!

[revdode]

You'll probably find you can't build something DIY for anywhere near the price that you can buy it.

The limit on the number of LEDs depends on the type you use and the power of your supply. This isn't as easy as it seems at first as different types of LEDs have very different power requirements. If you decide to carry on down the DIY route I'll try to help.

Waterproofing depends on the construction but pushing your LED into a bottle then forming a plug with silicon around the supplty cable at the neck of the bottle should do the job. You may need some silica gel to dry it out though. You really shouldn't see any problems with dirt inside the bottles.

Instrument LEDs (low power coloured) don't really get hot but the newer really bright high power LEDs (Philips lumileds, cray Xlamp etc.) have thermal problems you really don't want to deal with. They also need a driver which delivers constant current to work effectively. The down side is light output from low power LEDs is poor, you won't be causing much light pollution.

I wouldn't bury bottles in my garden as I have young kids. But as long as you don't drop stones on them I'd guess they wouldn't be likely to break.

All in I'd probably go for an off the shelf solution (low cost chinese white chirstmas lights) unless you enjoy tinkering.

[the.fee.fairy]

Thanks for the advice.

I wanted solar lights because the only mains point is the other side of the garden.

I'm having great difficulty getting solar fairy lights here in the UK!! I got a catalogue from Focus and they have some, but they're out of stock, and they don't know when they'll be getting some in

The only other places i've seen are either charging £60+ for them, or they're coming from Australia.

I shall have to keep looking and search around for solar panels and stuff to make my own.

I haven't got children, so the bottle edging will be free from football danger! I was more worried about either the effect of the ground freezing or the heat of the LEDs making the bottles crack.

Thankyou

[Muddypause]

1. Is there a limit to how many LEDs you can get running from one solar panel? If so, how do i calculate this?

This is dependent upon how big the panel is, and also, the capacity of the battery pack it's charging. I'd start from the other end - figure out how many LEDs you want, and how long you want them lit for. Then work out the battery size needed for this, and then see about a PV panel to charge the battery.

However you go about it, you will need a solar panel/battery pack, so lets look at how practical a DIY approach might be for assembling the LED part of the project. Here's an example I've been figuring out, with the aid of this jolly useful LED circuit wizard.

Example: Using these green LEDs (red won't show up well in green bottles, and it's easiest to keep all the LEDs identical within a circuit), and assuming we have a 12 volt power supply, we get this result from the wizard:
You can see that there are 4 LEDs daisy-chained together, along with a small 82 ohm resistor (it helps control the current). One end of the chain is connected to the +ve of the battery pack, the other end is connected to the -ve. You can add as many chains of four like this as you like (other numbers are possible, but let's keep things easy), each connected to the +ve and -ve of the battery. So if you needed 20 LEDs, you can make up 5 chains like these. I can't find an 82 ohm resistor on the Maplin site, but there is a 68 ohm version of this which would prolly do the job.

As long as you use decent wire, you can vary the distance between each LED to pretty much what you like, within reason, but try and keep the overall length of each chain about the same.

You can also see that each chain of 4 uses 25 milliamps, so 5 chains of 4 would use 125mA. Looking at a Ni-MH rechargeable battery, I see that an AA size is reckonned to be good for 1300 milliamp-hours at 1.2 volts, so 10 of these in series would add up to 12 volts and, in theory, provide about 10 hours of illumination. In practice, probably significantly less than this, as the voltage will drop as the batteries discharge. Maybe (guess) 5 hours of illumination. Bigger batteries than the AA size would last longer, or there may be better battery options, but solar chargers are readily available for AA batteries and the like.

Total cost of the LED chains for 20 LEDs:

20 green LEDs at 17p each = £3.40
5 resistors at 18p each = £0.90
Wire @ £3.69 for 25 meters
Plus a bit of solder, or maybe connector blocks if you are not so handy with a soldering iron = £2.79
1 roll of insulating tape to keep everything neat = £0.69
Total cost = about £12 plus the time to do it.

This, of course, is in addition to the power supply, which you will need whatever you do.

2. how do i waterproof it all?

You could put the battery(s) in a box or container, if it is to be outside. Drill holes for wires to go in and out, and seal these with silicone sealant. Could use this to seal the necks of the bottles after the LEDs are in them. At low voltages, PVC covered wires will prolly do without any further protection (the insulation may harden in sunlight), but if you bury them, make sure they are where you won't dig through them. Try and arrange things so that all your connections are enclosed inside the bottles.

3. Any idea how to stop the bottles getting dirty inside? I don't particularly want to have to take the bottles up every few months or so to clean them.

Reckon this may be covered by the above.

4. Do LEDs heat up a lot?

Most, hardly at all. Generally they use very little power, so there is very little heat output.

5. following on from that - are the bottles likely to break? if so, what's the best way to prevent it?

They are not likely to break as a result of putting an LED in them, but I can't comment about the effects of any other plans you may have for them.

Finally, if you play around with LEDs, remember that they only work one way round - if you connect the terminals the wrong way round, they won't light up, and may possibly be damaged (a diode is a bit like a one way valve for electricity - it only lets the current pass one way. A light emitting diode is one that happens to light up as it does it).

[the.fee.fairy]

Brilliant!!

Thankyou. That all looks pretty clear.

i think i shall take my dad to maplins at the weekend. Just got to do some research on the solar panel now.

So, to clarify: Solar panel gets connected to batteries (or i can get a solar battery charger), then LED strings get connected to batteries. I saw a switch thingy so that it knows when it gets dark, so i'd need to put one of those on.

And, using the above pieces, i'd get approximately 5 hours of light a night (which will be plenty!!).

Marvellous

Thankyou

[Muddypause]

So, to clarify: Solar panel gets connected to batteries (or i can get a solar battery charger), then LED strings get connected to batteries. I saw a switch thingy so that it knows when it gets dark, so i'd need to put one of those on.

And, using the above pieces, i'd get approximately 5 hours of light a night (which will be plenty!!).

Sounds plausible, dunnit?

I haven't looked into the solar panel bit, though - the above is just about the LED part. This may be the downfall of the plan. I dunno much about PV panel outputs, or rechargeable battery inputs, but looking at this example, it says it will charge two AA batteries in 4 - 6 hours, so to deal with 10 AA batteries on not very sunny days, you may need five of these.

Also another thing to think around - if you go the 10 x AA battery route, they will need to be connected in series to run the LEDs, but I suspect a solar battery charger will charge them in parallel (I don't know for certain). A solar charger that can output 12 volts would be ideal, cos then you can charge the batteries in the same configuration that you use them in. A solar charger should have a means to stop 'back charging' when the sun goes down, so it should be OK to leave everything permanently connected up in this format. A light sensitive switch would complete the setup.