Solar lights a challenge

Someone-Else · Post by **Someone-Else** » Fri Dec 28, 2018 4:46 pm

I really don't think much to solar lights / solar power, it's not the idea that I don't like, its the cost to do it properly and durability.
I can't afford to buy a "solar power kit" (That is big solar panel, battery, inverter and charge controller) But what I can afford is some stuff to run some 12v lights for my shed.
I am going to make a "project" out of this with pictures along the way.

As I said, I can not afford to spend too much so I am going with the following, all from ebay.

Solar panel and controller

Couple of lights

Any suggestions / comments welcome.
I will be using a 12v rechargeable lead-acid battery.

It's purely a test project.

I have NOT got anything yet.

big-all · Post by **big-all** » Fri Dec 28, 2018 5:42 pm

so a 20w panel on the average winter day may give you 20-30w over the whole day so would run a perhaps 1amp[12w] 12v bulb for 1.5-2 hours allowing for losses :dunno:

how much use are you hopeing for ?

kellys_eye · Post by **kellys_eye** » Fri Dec 28, 2018 7:10 pm

Your figures are wrong b-a.

A 20W panel will give (in theory) 20W continuously and over a whole day would therefore put out 20x8(hrs) = 160 watt-hours meaning a 3W LED could run for 50+ hours assuming full efficiency.

If you use a MPPT converter (standard on solar arrays) you maximise the power available from the panels (this is the 'controller' s-e links to) but manufacturers always over estimate their efficiency so only real-world tests will reveal how much you can get from them.

Being the UK the daily sunlit hours can vary A LOT so a figure of 50% efficiency for the solar side would be about right. Conversion is usually very efficient (90%) and batteries are pretty good too these days so perhaps figure for another 80% efficiency there.

Overall the efficiency is 1 x 0.5 x 0.9 x 0.8 = 36% so a stated 20W panel might best be used at levels of 7W. Still, over 8 hours this is 56 watt-hours and for a 3W LED means 18 hours operation from a DAILY charge.

Someone-Else · Post by **Someone-Else** » Fri Dec 28, 2018 7:16 pm

big-all, as i said its purely a test. I have no expectations at all, other than for it to work for a short time.

It came about because of This post

Someone-Else · Post by **Someone-Else** » Fri Dec 28, 2018 8:10 pm

UPDATE. I have ordered it, but I have got smaller Lights (less £)

big-all · Post by **big-all** » Fri Dec 28, 2018 8:23 pm

winter cloudy days 8hrs off day light 3-3.5w per hour ?? :dunno:

the point i am making is when you need it most you get the least output

yes it may be more but its unlikly to average very much but iff you only expect 3 or 4 and get 5 or six you will be happy need 5 or6 and get 3 or4 you will be dissapointed

Someone-Else · Post by **Someone-Else** » Fri Dec 28, 2018 9:02 pm

I am not worried, I have mains lighting in my shed, this is just to prove or not if solar powered lighting is any good in the UK (I think not)

kellys_eye · Post by **kellys_eye** » Fri Dec 28, 2018 9:06 pm

Solar is 'good' in any place - except for the capital outlay. There are very few situations where you'd break even or come out on top using a solar installation you pay for entirely from your own pocket.

Of course the 'subsidy suckers' that leech off the poorest would probably argue the point.

omegac · Post by **omegac** » Sat Dec 29, 2018 10:37 am

Subscribed...

Someone-Else · Post by **Someone-Else** » Sat Dec 29, 2018 2:38 pm

I am doing this test just to see if / how (well) it works, I do not need the lighting in the shed.
I have ordered two 10W LED lights (For vehicle use) so one can be inside and one outside.
The solar panel is 20W But I have no intention of running the lights during the day. (So the panel can charge the battery)
The solar panel is "Slightly flexible" (it has no glass or frame) so I am going to mount it on some timber, and fix the timber to a "pole"
I am not expecting any of the parts to arrive until next year.
I am hoping to take lots of pictures.
I know I have chosen cheap bits, but then I don't have a lot of money for this.
I will list costs on the pictures.
I am crap at woodwork.

If you have any questions, please ask.

wine~o · Post by **wine~o** » Sat Dec 29, 2018 5:47 pm

I've got "solar lighting" in my greenhouse...

kellys_eye · Post by **kellys_eye** » Sat Dec 29, 2018 6:41 pm

I've got a solar panel on my head - as my son likes to keep pointing out.

Other than the simplification of not using a mains connection I'd not bother with solar/battery for LED lights as the mains supply is so cheap (comparatively) but fitting them in sheds with no other mains supply is a very useful and practical solution to an issue that many face.

We've been through the figures and know that you'll never save money but the final cost and details of how easy (or not) and efficient (or not) your system ends up being will be interesting to discover.

Someone-Else · Post by **Someone-Else** » Sun Dec 30, 2018 5:45 pm

I have made a start.

More pictures to follow as and when the kit arrives. Please also note (As I said earlier) I am crap at woodwork. Total cost so far is £0.00 as I have used odds and ends I had laying around. (Which is why the timber has drill holes in it)

: Where the battery and charge controller will go. (He said hopefully); sp1.jpg (170.15 KiB) Viewed 4256 times

Someone-Else · Post by **Someone-Else** » Wed Jan 02, 2019 7:26 pm

The LED lights have arrived

: 12v 10Watt; sp3.jpg (287.29 KiB) Viewed 4203 times

I have two of these. £3.80 each.

The bad news is the solar panel has only been posted today

I was expecting it to arrive tomorrow

big-all · Post by **big-all** » Wed Jan 02, 2019 10:06 pm

how many watts are those lamps ??
:dunno:

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