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External Home Lighting

That’s a name I concocted as I could not think of anything better as a title for this article. I did not want to say “solar lighting” as that limits the conversation So what do I mean by this? – and what is the point of this article?

Totally solar-poweredThis is about externally lighting your property for fun/amusement or even security. I’m writing this because invariably the subject comes up in pub conversations and I often promise people to follow up the conversation later – I then usually forget or we simply run out of time.

Why should you listen to me? Because I’ve designed and built home automation systems for several homes now, i run a very successful blog on the subject of home control and that means means I get constant feedback…  I have a very good grasp of the subject thanks to knowledge, feedback, trial and error….

Lighting up your house/cave/cottage externally is not THAT easy – not if you want to do a good job – but I appreciate that some will want a quick solution so I’ll cover the easy options and explain why they may or may not be a good idea.

I’ll also promise to avoid where possible any technical terms with the ONE exception of a trivial formula you may need to calculate your needs, so this article is NOT for techies who will invariably know better anyway and I don’t want to start a raft of discussions at that level.

There is so much to talk about – so I’ll try to break this down so you can go right to where you need to be. Solar versus mains power versus battery. Stand-alone versus “systems” etc. Let’s start here:

How to power your lighting

To some extent the answer to this depends where you live. If you’re in Spain you have lots of solar power available. If you’re “down south” in the UK, to a lesser extent that is also true. If you are “up north” in the UK you may need to look up the word “solar” on Google – trust me – I was born in the North and have two houses there.


filamentI’ll kill this one off before we start… if you’re still using lights with a little hot wire in them – it is time to move on. At this time there is one real solution – LED (light emitting diode). At least in theory these are pretty, low power, efficient, long lasting (but read on). Ok, there are other solutions “around the corner” but for for availability, flexibility and increasingly cost, LED is the answer.

What is a LED?

LEDIn simple terms, a piece of material that converts low-voltage electricity directly into light – it does not heat a wire, it has no gasses, direct conversion – it’s only issue is that currently we cannot achieve anything remotely like 100% efficiency – so the losses come out as heat but not as much as heating up a wire to produce light. LEDs produce very pure, clean colours – witness Christmas lights over the last few years for example and modern TVs.


coloursAt this point I’ll assume we’re talking exclusively LED. White LEDs – at least the cheap ones, do not seem to last as long as coloured ones and that is because the technology is different. Given a choice I would marginally prefer colour for reliability – even if I use the colour to make white (red+green+blue=white .. yes, honestly). If that interests you – we’ll look at this later on and have a play with colours. For now, consider your TV – generates most colours – yet there is NO WHITE in your TV, only red, green and blue (take a CLOSE look). Of interest “white” LEDs are actually blue with phosphor producing yellow. Yellow and blue make white.

Solar versus mains versus low-voltage

Yes you can get mains-powered LED external lights – without a transformer. I don’t recommend them – for reasons which will become apparent later – in a word, corrosion.

Mains-powered via a transformer – means there’s a little black box that plugs into the mains, producing safe low voltage and feeding a bunch of lights – this is how most Christmas lights work. Relatively cheap to run, hassle-free. If you are not in an area with plenty of direct sunlight – this might be a solution for you.

Solar powered

Before we start, a myth to kill:

“Modern solar panels work without the sun”. Bollocks. In order of preference/practicalities:

  • Best – orient the panel to be directly facing the sun at all times, moving regularly.
  • Next best – point the panel south (UK/Spain) at 45 degrees so mid-day it is getting hit by sunlight hard. Getting the most in the summer is not the point – getting most in the winter is the point – when the sun is lower in the sky.
  • Normal – point up – make sure there is nothing casting a shadow on the panel – look for the most direct sunlight for as long as possible.

So of course – you do get output from solar panels on a cloudy day but it is SO low, it is often hardly worth it unless you get paid for producing electricity however poorly – but that’s another conversation and yes, I’ve physically tested this. Clearly most of us are not going to have solar panels rotating all day – so the next best thing is to have them fixed-angled toward the mid-day sun – even that is not always practical.

Solar powered lighting can be generally split into three areas of interest:

Individual lights

Solar lightsWe’ve all seen them – B&Q, Brico-Depot, Maplin, B&M – £1 each – stick them in the ground and that’s it. Generally fun at first then a disappointment.

The problem here is that it never rains in China. That is, these lights are made to a price and generally speaking that does not include water-proofing or UV-light-proofing. I guarantee that within a short period of time one or more of the following will happen in this scenario with lots of cheap, individual lights.

  • The plastic will crack or just fall to bits after a year or so.
  • The solar panel will go foggy and collect less light and eventually die.
  • Rust will finish off the LED which will first look brownish then snap or simply stop working.

Is there a way around this? Possibly by throwing money at it – I HAVE had a solar light model from Maplin at something like £6 a lamp, made from decent stainless and glass that has lasted several years. Maplins don’t do that any more and most of their stuff is obscenely expensive. If you insist – when you are in the store looking at these lights – imagine dipping one in the sea for a day or two – would you expect it to work after that? If not – it is probably going to disappoint. In the UK, DAMP will get it, in Spain the sun will systematically destroy it along with overnight condensation.

At the very least try to avoid solar panels with plastic/resin covers – glass is much better – but the water WILL get into the solar panel eventually and rust everything. Lacquer it all? Maybe but will that go off in the sun over time? Certainly don’t lacquer over the glass as that defeats the object. Will it cost more than it is worth?

What about positioning? Another issue with these lights.. positioning. Can you guarantee a few hours of direct sunlight will hit the lamp every day? Is the best place for sunlight the best place for the lamp? usually not. Most of them have flat tops – depending on where you live the sun is generally NOT sitting directly above you – ever!

However, the above is the SIMPLEST solution and often the cheapest. You have little control over this setup – if you’re happy with that, fine. If you want the best bargains in cheap rubbish – check out B&M stores (in the UK, if you have one). No really – at the bottom end of the market they are very good.

Solar light kit

Kit of lights with a separate solar panel – a kit you buy with some lights on a wire with a separate solar panel at the end. Fairly rewarding experience depending on your choice of kit. Quality and material considerations as above – but there is one big advantage of a separate solar panel – you can put the lights where they are best served and the solar panel where it will get the best light. Avoid VERY long strings of LEDS – you’ll likely be disappointed by the output.  The more lights, the more there is to corrode. Oh and nail varnish does not work – it simply goes brittle – trust me I’ve tried it.  Most sealing solutions you could try will go frosty in time and/or look awful. Can you shield these lights from rain/damp? Most are the same old crap with different plastic shapes. Few are meant to last. I’ve used them INSIDE a pergola – with the solar panel up on the roof in a corner, facing the mid-day sun. Works a treat but the corrosion arguments apply as for single lights.


lightsI should mention solar security floods which light on on demand… some are rubbish – some last for years. If all you need is a little light to help avoid falling over in the dark – these might be just the job – expect to pay £10 or more each. Make sure they come on only with movement – and the bigger the panel generally the better. Ensure they get as much direct sun as possible. Many will cover you for several days of no sun however because they only come on when they detect movement. We have a holiday rental home and at the back door and parking area these are a life-saver.

A full solar installation

Several lights in various combinations – with a solar panel installation consisting of battery, regulator and solar panel with a timer or other controller and your choice of lighting.  Can be fairly easy to set up – or very hard depending on your requirements. Most rewarding experience, most time consuming. You are in full control of what kind of lighting, a proper solar panel will last for many years, camping battery should be good for 3 years or maybe much longer, etc.. but this is a more expensive and more complex solution for true enthusiasts. Having explained the simple solutions with their benefits and issues,  I’ll now concentrate on this option.

The Big Installation

So many options here but generally you will need:

  • Some low-voltage lights
  • A solar panel
  • A battery
  • A controller

Solar panels are cheaper than ever before. Controllers are cheap. Batteries are not cheap.

The only place in this blog entry that you will see any maths is here – it is unavoidable but simple.

You want to light things up from the sun – so you need to generate power from the sun. You need to store that power and there must be enough of it to power the lights for as long as you have in mind.

We could talk about watts, volts and amps. An easy one to discuss is amps – think of it as water flowing into a bottle. You can store amps – and you can let lots of them out over a short period or you can stretch it out – less amps over a longer period.

Consider a car battery – it might say on the side – 50AH. That means that full charged it will let out 50 amps for 1 hour. Or, say, 25 amps for 2 hours – or…. 1 amp for 50 hours – etc., – you get the general idea.

It really is more complicated but let’s pretend it isn’t.  ASSUMING a 12v battery, assuming a compatible solar panel and assuming 12v lights – it can look simple – the lights might take, say, 25 amps in total – so your 50AH battery IF fully charged will run them for 2 hours.

And this is where the simple version ends. Fully use a car battery until it is flat and you’ll likely damage it. So you have to stop that happening. OR you can select a LEISURE or CAMPING battery so beloved of caravan owners – these look like car batteries but are better able to handle being left full or left flat, drained etc. For the example battery expect to pay well under £100 online.

But then in this world we’re assuming everything is perfect, 100%  efficient. It is not.  Assume the solar panel claims are based on a perfect sunny day in Spain – that the controller will not lose any power and that the battery will give out exactly what you put in – do that and you’ll be sadly disappointed.

So – we have a solar panel that puts amps into a battery via a “controller” – this is a black box that stops over-charging, over-discharging and generally has 3 sets of “terminals” – ie 2 wires each. Wire the box to the solar panel, the battery and your lights and you’re done – well, apart from turning them on and off of course.

In the UK expect half of what the panel claims. On top of that, whatever you think you need in terms of amps – add 25% to include battery and controller losses.

Here is the one calculation you need to do all of this on your calculator – W=A*V. Watts equals amps times volts.  If you have 2 of these you can calculate the third.  For example – you have a 12v, 12w light – how many amps does it need?  12=?? * 12. Fill in the blank. That’s 1 amp.  You have a lamp that uses 2 amps at 12v – how much power does it need? 2&12=24 watts. THAT much really is that easy – so now we can figure out what power we need – that tells us what battery we need – which in turn points us to the size of solar panel. Just remember that simple calculation and you can work it all out.

Clearly, variations of the one formula are:

  • w=a*v
  • a=w/v
  • v=w/a

So – let’s say that we want a lot of lights – all 12v and in total they take 10 amps.  That is 120w. How many hours would we like them to stay on – 2 hours? That is then 120 watts for 2 hours – that is 240w/Hours. That’s a lot.

If you can’t do that formula – here’s a table – amps across the top, volts down the left, watts in the middle.

tableOur 12v, 50A battery can deliver 12*50= 600W/Hours – EASILY enough – but can we charge it? We need a solar panel that can deliver 600W for an hour plus a margin for inefficiency – let’s say we need 800W for an hour… OR 400w for 2 hours OR 100w for 8 hours etc. How many hours of direct sunlight do we expect in a day? What reserve would be like for 3 cloudy days in a row?

I can’t help you there because your situation is unique. Let me tell you what I have and why.

regulatorI have a 50A/H 12v battery because it was reasonably priced.  I have solar panels totalling 80w because they came cheap (free actually from a friend).  So they give out maybe 6 amps for most of the day – let’s say in Spain, 10 hours.  My controller handles 10 amps because the cheap Chinese ones come as 10 amps or 20 amp versions. So the controller is WELL able to handle the anticipated power from the solar panel/s.  With 6 amps out from the solar panel – I can fully charge the battery in just over a day assuming good weather. In an ideal world for my battery I should have stronger solar panels – they usually describe their output in watts so 120w would have been nice. Such a panel should cost under £100.

So I can use most, but not all of the power in that battery – every day in summer and maybe 70% or more in the winter. In England I’d want to ramp up that solar panel  to get the same – especially in the Northeast. 200w would be nice there – but beware if that means best case over 10 amps coming out of the panel, a more powerful controller would be needed. 20 amp controllers are cheap as are 10 amp controllers. Expect to pay £20 or less from China.

The battery should be protected from extreme sunlight and extreme cold. A nice breezeblock box would be good – with some insulation. Batteries don’t like freezing.

So now – we come to lighting – what a big subject. I will assume LED throughout. Let’s assume  I have that 50A/H 12v battery – let’s say I use half of it’s capacity in a day to be safe. 25*12=say 300W for one hour… but I want my lights on from dusk till midnight-  say 3hours? So I can run up to 100w of lighting for 3 hours in the summer- but let’s think overall – all year around. Note that all of these calculations come from that simple formula above – really not complicated.

LED SpotlightWith a total of say 60w available – I can do lots. 10W LED floods are cheap – maybe £20.  I use 3w green floods – several of them to light the place up.  Cheap, waterproof, sun-proof, last for years – £10 – £20 each, maybe more, maybe less from China.  I also like to use 12v LED STRIP. This is becoming very popular – the Chinese stores in Spain sell variable length strips of them for 6 euros a metre in most colours (remember what I said about white – LED lights do not light to run hot – and white less than the other colours). The insulated stuff is fine – but how hot they get is out of your control. I arrange non-waterproof strip in downward-facing aluminium channel – so any heat is dissipated by the strip. My lights are lasting for years – with exceptions (some white). LED Strip takes lots of power. Mostly available to run on 12v (isn’t that handy). Beware of snake oil – prices vary, so does what you get.

LED Strip

blue stripWaterproof/non-waterproof, colour, LEDs-per-Metre, with controller or without controller… so many choices.  Firstly – how many LEDs per metre – cheaper stuff has less – look for 300 or 600 LEDs per metre – some go as low as 150 LEDs per metre so that bargain may not be as good as it looks – on the other hand – the less LEDS-per-metre the less led strippower is needed. If you are not a technical whizz – get a controller – inexpensive infra-red hand-held – or more expensive over-your-phone controllers – the choice is VAST.  If you want one colour it is easy – if you want all colours – that’s RGB strip – avoid the old crappy type with a red, then a green, then a blue light. Ignore those – old stock. Modern RGB LEDs have all 3 in one LED – and can truly produce just about any colour you want. Typical 12v LED strip can be cut at intervals of every 3 LEDs – so easy to make as long or short as you want. Typically the stuff comes in 5 metre rolls.

For power, full RGB LED strip can take well over 1 amp per metre – that’s 12-20w per metre. Doesn’t take long to eat up all that battery capacity. Maybe better to use less LEDS-per-metre in this case?

There are two distinct types of RGB colour LED strip – the one I mention above generally runs at 12v and has 4 wires… a common +12v, then grounds for red, green and blue. You can ground them and get up to 8 colour combinations – or you can what is called PWM them, that is pulse them too fast to see and by varying the pulse width – you vary the output and perhaps the colour. Another option is serial LED strip in which each LED not only contains red, green and blue components but also a tiny processor. Controlling these is complex but you don’t need to worry about it because the controllers are dirt cheap. Essentially a serial signal is sent to the first LED to tell it what colour and brilliance it should be. From that point on, the LED simply passes th message on. Hence massive colour displays can be made with no more than 3 wires (ground, 5v and signal).

Cold or Warm?

warm and cold lightCOLD white light is the horrible, stark white colour you get from Cheap Chinese fluorescent lights – the ones usually marked “6500K”. WARM light has some yellow in it. With controllable RGB lighting you can have ANY TYPE OF WHITE YOU WANT. Experts tell us that white shifted toward blue in the morning is good – shifted to warm orangy at night is good.  Buy fixed colours and you’ve had all that – buy more expensive RGB and you are in control. But that might be way over the top for you.


If mixing RGB colours, Here is some examples of how to make warm and cool light as well as various colours using that gadget I linked to earlier.. Note the positions of the RGB sliders… try it for yourself..

Take a look at this link on your PC… play with the sliders to make just about any colour you want. You can do that with LED RGB (red-green-blue) lighting – by adjusting the red, green and blue you can get warm white, cold white, purple, cyan, majenta, pink… anything you like.

Using that slider demo above- try red full on, green at half way, blue around 3/4 up – you get pink.


Full red, back the green and blue off a little – and you get warm white.


This is the most difficult part of a big installation – a black box that turns stuff on at dusk AND off at, say midnight is not a B&Q off the shelf – light sensors pick up dusk and dawn but not time – so you may need a combination – or you may chose to do this by hand or by remote – can’t really advise here as everyone’s needs are different.

The best solution would be one that knows when “dusk” is – and that changes all the time – and also the time – for example in the summer, dusk until midnight – in the winter, dusk until 10:30pm to save power – better yet, a REALLY complicated setup like mine detects battery voltage and assumes lights out at midnight unless the battery voltage drops to 11v in which case lights off now – but that is not simple – as soon as you turn the lights off – the battery voltage will come back up – so you need rules – when the voltage gets low, turn the lights off (or some lights off) and KEEP them off until the next day. Simple B&Q timers don’t do this – microprocessors (computers) do.


No one, simple solution for this one – it’s up to what you want/need.

I hope the above is helpful, it is based on years of getting it wrong and filling the bin with dead bulbs/kit. Now I have it right – I might want bigger solar panels but generally I have a good working setup – I’ve gone the whole hog – everything is automatic but I can over-ride controls via my phone or PC from anywhere. You may or may not consider a simple timer is enough. At the very top-end, LED strip that runs on 5v and is controlled by computer can control each individual LED to be any colour or brilliance you like. That’s how modern airport advertising displays work for example. That is available on Ebay per metre. The sky is the limit.


This whole article is intended for non-techies – but invariable there will be some techies looking in – if I may suggest – this is of course just the beginning – there is plant watering, internal lighting and heating, climate control and much much more ….  http://tech.scargill.net/home-control-2016/

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