Solar panel help wanted, please.

amfisted · 21 Jun 2015

Not sure where this ought to go, but I am sure it'll be shifted if its in the wrong place.

I've recently bought a solar powered PIR...errr... floodlight.

The 5m cable attached to the small solar panel supplied with the light is too short to allow me to fix the panel in the preferred location for maximum exposure to sunshine, which is on the chimney stack.

On the packaging, the solar panel is stated as being 10w 80MA, and the battery in the light as 3.7v 1500MAH Li-ion. What I need is either a 5m extension lead for the existing panel or a complete panel with a 10m cable or longer.

Could someone point me in the direction of a suitable retailer of such items, please? I've tried Ebay but the plethora of different panels available on there has served only to confuse this simple soul.

Thank you.

Taylortwocities · 21 Jun 2015

Is there a connector on the existing cable at either end? If not, can you access the wiring at one end, or the other?
How many conductors are in the cable, and what size are they.?
There are LOTs of people that sell cable, of all types.

ban-all-sheds · 21 Jun 2015

Is the solar panel relevant?

You need a cable, to carry a certain current over a certain distance with a certain maximum volt drop.

That's it, surely?

amfisted · 22 Jun 2015

Being solar panel cable, I assumed that it might not be available from the usual outlets.

I'll ask at my local electrical factors store tomorrow.

ban-all-sheds · 22 Jun 2015

It's cable.

It's cable.

It's cable.

It's cable.

amfisted · 22 Jun 2015

Last time I looked, this was a forum where you asked questions in order to find things out.

Even questions that might be considered daft ones, by those already in the know.

Taylortwocities · 22 Jun 2015

amfisted said:
Last time I looked, this was a forum where you asked questions in order to find things out.

Even questions that might be considered daft ones, by those already in the know.

But we no NOTHING about the thing you have bought. We haven't seen it, you have. We haven't examined it, you have. We do not even know what sort, style type of cable it has or how it is connected.

It MIGHT help if you were to provide a link to the product you have bought, or perhaps the make and model number! or perhaps a picture or two. Or have a look at this mystery cable and see if there is any writing on it.

Give us some clues, nobody on here is clairvoyant.

amfisted · 22 Jun 2015

There was no need for the sarcasm; none whatsoever. Its a solar powered floodlight, and they're widely available, as I'm sure someone here would have loftily explained if, rather than buying it myself, I'd come on here and asked where I could get one.

As for the "it's cable" comment; well, I can imagine the sort of response I might have received had I asked about using telephone cable to wire in my cooker.

You've told me yourself that LOTS of people sell cable, so rather than waste any further time talking on here with people who seem to think that answering questions from DIYers should be seen firstly as an opportunity to demonstrate a talent for scorn and condescension, and secondly as a chance to help, I'll head for the electrical factors store later.

I'm pretty sure that they'll be helpful first, and sarcastic a long way second.

Taylortwocities · 22 Jun 2015

I am willing to be very helpful, but cannot answer your Q without more information.
You have basically asked "what tyres do i put on this car that I have bought". Of course, everybody knows what a car is, so what's the problem.

A simple ebay search for "solar panel cable" coses up with about a thousand different types. One of those might match the cable that only YOU can SEE.

MORE INFORMATION, pictures. Is the cable 2,3,4 core, what. Is there a connector on the end. etc etc.

ericmark · 22 Jun 2015

No flexible cable designed for power in the UK will be less than 0.75mm² and that is ample for a solar panel of the size you have and it is very likely to just have two cores so likely some 2 core 0.75mm² cable will do the job.

However as already said that is assuming it is using what would seem to make sense but since we have no information I am just guessing. Since outside the cable may be sealed in a way which prevents re-entry and could be of a type which does not lend itself to being joined. I have in the past made mistakes and remember buying some simple speaker cable only to find it could not be soldered clearly not copper.

So the previous posts are correct in asking for more information. If it were me I have a length of old lawn mower cable going spare so I would open up the device if possible and see if I could use that. I have in the past bought cable and considered if I can't use it then it will do for something else.

To charge a battery voltage of the battery is important. Somewhere there is likely some controller. We would hope next to the battery but it does not have to be there so it may use 4 core cable two cores used to monitor battery. It is likely it uses the solar cells to work out when to switch on again this may mean an extra core. It could use for example 5 black cores so you would need to strip the cable very carefully to label the cores.

Again picking up a lamp in a QVC outlet store for buttons you may take a chance, but pay £50 and you want to be sure.

paulc2 · 22 Jun 2015

Voltage drop on what is a low voltage circuit is critical here. Its fairly simple though, if the circuit was 5m in length (and 5m neg, making 10m run) and you want to extend it to 10m (20m run total) then it would need to be at least twice the thickness if the same cable type. Then you have the connections to think about - how are you going to connect it, in a weatherproof way? Are these connections perfect or will they also have a voltage drop across them? etc

I'd be tempted to find a way of installing it as-is, without disrupting the cables on it. Another 5m won't make any difference given that the sun is something like 100 million miles away. The angle of the solar panel will though - so maybe spend the money on decent brackets or a frame for this too. A 10W panel won't be too onerous to mount at the correct angle.

amfisted · 23 Jun 2015

Thanks for your replies, Paul and Eric, and apologies, Taylor, for my rather tetchy reply to your penultimate post.

I took my solar panel/ light setup to the local electrical factors, and the chap there also warned of the likelihood of voltage drop if the cable was extended. After some searching of suppliers online he did find a cable that appeared suitable, but could not guarantee that it would be the right one without opening up my cable and identifying the number of conductors (which I think is what you suggested earlier in the thread). It would have cost about 11 quid including carriage for something which might have been the wrong part; so in the end I concluded (again as suggested above) that it might be best to take the existing cable and do the best I could with it.

I secured the panel via masonry screws to the mortar between two ridge tiles on the roof, stepped back to admire my handiwork and cracked a tile. Being Stonewold Mark 2, (so I'm told) it took me some time to track down a replacement, and most of yesterday was consumed by that task. However, I found and fitted the tile and I'm happy with the positioning of the solar panel.

Thanks again for your help.

amfisted · 24 Jun 2015

One final question before I put this to bed.

Is it possible for a 10w solar panel to overcharge a 3.7v battery? At present, the light connected to the panel is usually only triggered when I take the dog out last thing at night, and we've had some good, long sunny days just recently; so at least until the days become considerably shorter, very little of the stored energy is likely to be used. I've had a look online, but most of the information about the potential for overcharging of batteries seems to refer to much more powerful installations than my little QVC light.

Of course I'm not complaining about the sun, but I'd hate the battery to burst into flames.

Taylortwocities · 24 Jun 2015

Do not worry, it will be fine. Just like your car battery does not explode if you go on a long journey with the lights off!

It should also include circuitry to stop charging when it is full. Something almost like this.

amfisted · 25 Jun 2015

Thanks for the reassurance. I've now discovered that although the lamp's "time on" is meant to be adjustable between a few seconds and two minutes, in reality it only appears to provide settings at either end of that range. So I've left it on the two minute setting, which will ensure that it uses the maximum amount of stored energy under circumstances where, at this time of year, it'll hardly ever be activated.

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Solar panel help wanted, please.

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