Solar lights a challenge

Someone-Else · Post by **Someone-Else** » Wed Jan 02, 2019 10:48 pm

The LED lights are 10watts each (as written in the picture title)

BUT what I do not understand is:

The lights are claimed to be 10w (No problem)
But count the individual LED's (save time, there are 12)
My guess is that each LED is NOT 0.833 watts, maybe 0.5 w? which would make the whole light only 5 watts, odd thing is, when i looked at the 20w light it has 24 LEDs, and the 30w light has 63(ish)
We shall see.

Oh and I am not fussed at what they really are, but I am interested in how long they will run for / how the solar panel does.

kellys_eye · Post by **kellys_eye** » Wed Jan 02, 2019 11:05 pm

Simple to test for efficiency. Power them up, multiply the current draw by the voltage. LEDs of such 'value' rarely meet the stated specifications and will inevitably have imbalanced LED die's which will result in premature failure but that's what you get when you pay peanuts.

That said, I've been running seven AC mains powered versions that cost under a tenner each and they've been on 12 hours a day, 7 days a week for the last year (and more) with zero failures!

BTW you really SHOULD do the volts/amps test to get an idea of the efficiency of your system (when it's complete) else the work you're doing isn't worth jack shirt (for information).

big-all · Post by **big-all** » Wed Jan 02, 2019 11:42 pm

someone-else wrote:The LED lights are 10watts each (as written in the picture title)

BUT what I do not understand is:

The lights are claimed to be 10w (No problem)
But count the individual LED's (save time, there are 12)
My guess is that each LED is NOT 0.833 watts, maybe 0.5 w? which would make the whole light only 5 watts, odd thing is, when i looked at the 20w light it has 24 LEDs, and the 30w light has 63(ish)
We shall see.

Oh and I am not fussed at what they really are, but I am interested in how long they will run for / how the solar panel does.

12w is 1 amp at 12v so a 7.2ah battery will run a 10w light for 6.5 to 7hours allowing for losses
your panel on a bad day may only give you 20w total or perhaps 60w on a good winter day but only time and practice will tell so would expect one or both lamp powered for say 6-20hrs a week may be possible without taking the battery home to be top up charged but no one knows until you try the system out
as the input power consumption and tramission losses can be so extreme and unpredictable

kellys_eye · Post by **kellys_eye** » Thu Jan 03, 2019 12:46 am

Too many real-world variables to take pot shots at the possible results.

best wait to see what s-e finds out with the stuff he's using. It could represent the worst case or (unlikely) the best case such a setup can achieve. I suspect it will have sufficient power to allow the use of the light(s) when they're actually needed - say a few hours or so in the evening but nothing substantial. I actually hope I'm wrong!

Someone-Else · Post by **Someone-Else** » Thu Jan 03, 2019 5:42 am

Thanks guys, but do bear in mind this is only a "Test" project, I don't care how long anything lasts, the shed is at the bottom of the garden, so the battery (When it arrives) will always be "home" and I was going to check the lamps wattage when the battery arrives. (I want to be as "fair" as possible, so only want to use parts that I have ordered)
I only pointed out my "concerns" for the actual lamp wattage as a starting point, I am curious to see what the charging voltage is, as it should be around 13.8 for the battery I am getting, but that is another thing to be tested.

[Voice over person speaks]Stay tuned, same Bat time, same Bat channel. [voice over person finishes speaking]

Ok, so I only found same bat station.

kellys_eye · Post by **kellys_eye** » Thu Jan 03, 2019 8:37 am

.....same bat crazy....

Someone-Else · Post by **Someone-Else** » Sat Jan 05, 2019 8:50 pm

: sp-1.jpg (344.83 KiB) Viewed 3635 times

I have been out all day, when I got home I found the above had arrived.

kellys_eye · Post by **kellys_eye** » Sat Jan 05, 2019 11:13 pm

Someone threw some cables in front of your doormat?

Someone-Else · Post by **Someone-Else** » Sun Jan 06, 2019 10:05 pm

Its all up and................working

: I have made a start; sp4.jpg (265.21 KiB) Viewed 3620 times

: It's powered up; sp9.jpg (260.51 KiB) Viewed 3620 times

: In its final position; sp8.jpg (362.51 KiB) Viewed 3620 times

: How i chose to secure the panel; sp5.jpg (310.09 KiB) Viewed 3620 times

: From underneath; sp6.jpg (211.29 KiB) Viewed 3620 times

: sp10.jpg (276.84 KiB) Viewed 3620 times

Of course, the question is how long will it last for, this is only day 1. I had problems setting up the charge controller, the blurb says long press on a button to enter programming it took several attempts to get it right, then I have the on duration option, I couldn't get that to the dusk till dawn option, so I settled for 4 hours, so I am hoping the lights will switch off 4 hours after they came on. (There is one light in the shed and another as you can see outside the shed) I guess it will be a case of wait and see.

The solar panel is flexible (not bendable) so it has no frame or glass, so it needed to be mounted on something, easiest for me was timber, its on a short pole, because there is (I hope) no need for it to be too tall, and the taller the pole is the more it can sway, which means the more fixings it will need.

I am sure the battery will only last 3-4 years if I am lucky, so that's say £5 every year for "free light"
I am glad that I have tried it, it has been painfully slow to build (I did say my wood working skills are crap) I have no idea how long the lights will last.

If you have any questions, please ask. (I still have to check the actual wattage of the lights, will try soon to do that)

Costs?
All the timber was just odds and ends I already had, as was the pole (I got it for another project but decided against it)
The Solar panel and charge controller were £39
The lights were £8 (For two)
The battery was £20

Everything came from ebay

Someone-Else · Post by **Someone-Else** » Sun Jan 06, 2019 11:04 pm

Well, 4 hours later, the lights have switched off. (Or the battery has gone flat, but the lights are off, not dim)

kellys_eye · Post by **kellys_eye** » Sun Jan 06, 2019 11:14 pm

Call it £70 all-in.

Assume you bought the lights in the 240V version at around £5 each (total £10) that leaves £60 for 'energy'.

2 x 10W LED's = 20W. Assume energy is 15p/kWhr therefore the £60 would pay for 400kWhr or 20,000 hours running a 20W LED setup. 4 hours/night = 5,000 nights = nearly 14 YEARS of use (assuming the LED's last that long!)

Of course you'd have to run in a power cable and purchase those parts but you get the idea - solar is good for areas where power access is limited but otherwise only works if it's subsidised.

Now, let's see if the system can charge the batteries sufficiently to allow for that 4 hour usage...... it should, but I'd like to see the real power figures to see how good (or not) such system really are. I suppose if you paid for 1st class products you'd get better efficiency but it still wouldn't make the system viable in cost terms but cheap'n'cheerful fits my demographic quite nicely

Thanks for taking the time to describe the process. Let's see the final details when you get them.

Someone-Else · Post by **Someone-Else** » Mon Jan 07, 2019 9:49 pm

Oh there is a surprise (not)

: sp11.jpg (257.81 KiB) Viewed 3605 times

The battery has gone flat.

Each LED lamp draws 700ma (which makes them around 8w)

I am going to charge the battery (not today) and change the on time to 2 hours and see what happens.

But it looks like that unless you have a huge solar panel and some sunshine then its a waste of money.
Today has been "over cast" but then I figured this is what would happen, but I will give it a few more days and see what happens. (I have to charge the battery, change the on time etc)

Oh and if anyone is wondering about the angle of the solar panel.......... it depends what time of year it is as to what the angle should be, so I chose the angle you see. (It was halfway, which is better than to keep adjusting it every few weeks)

kellys_eye · Post by **kellys_eye** » Mon Jan 07, 2019 11:29 pm

Unless the panel actually tracks the sun then the angle will make little difference (other than when it's in the approximate 'correct' position i.e. not pointed at the ground!)

Starting with a fully charged battery would have been a good idea

but your example still illustrates the kind of thing other would do too so quite relevant. The 8W real-world figure for the LED is also typical (see BigClive for similar examples) so again, no surprises.

What we really need are the figures for the solar panel - this is the 'killer' part of the system and determines whether or not the overall setup will ever work satisfactorily.

Any way to monitor the output voltage/current over a typical overcast and/or sunny day?

Argyll · Post by **Argyll** » Tue Jan 08, 2019 9:27 am

This is interesting.

Could this set up be used to trickle charge a 12v battery?

kellys_eye · Post by **kellys_eye** » Tue Jan 08, 2019 10:30 am

Argyll wrote:This is interesting.

Could this set up be used to trickle charge a 12v battery?

This type of setup is typically used for such a purpose. Unless you spent 'gazillions' on a subsidised multi-kW system you'll never get a system to work efficiently in the UK.

There is a good reason why no solar/wind manufacturing factory is powered by its own product............

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