Solar lights a challenge

Argyll · Post by **Argyll** » Wed Jan 16, 2019 10:39 am

Sorry I've been incredibly busy.

A bigger battery? or two in parallel?

I've already tried this before. It means I have to buy twice the amount of batteries and of course lug twice as many batteries around. I think solar is the cheaper option.

The only useful position (face) for any solar panel would be the top. If you think a panel would survive vandalism then you next need to consider if you can get the wires into the case without cause a leak.

I've answered this in a previous post

But one thing I forgot to ask: just how long do you need it to work for? If the recording device has to be accessed (emptied) at some time, when is this? Annually? Fortnightly? This would determine whether just adding battery power would be the better route.

Ideally a couple of months. I normally go on holiday for a month at a time so have to play catch up when I return.

You could also consider using different battery technologies - lithium perhaps - and get an awful lot more Ahr's in the same sized package, quicker charging too.

I suppose it all depends on cost. Can you recommend any batteries and I'll have a look.

kellys_eye · Post by **kellys_eye** » Wed Jan 16, 2019 7:30 pm

What's the input voltage specification for the recoding device i.e. is there a min/max voltage it can accept without damage?

You say it can work down to 6V (but that knackers the battery) and the battery is 12V so presumably it has an input of 6-12V DC or is this larger?

Argyll · Post by **Argyll** » Wed Jan 16, 2019 10:02 pm

I think it can take up to 24v but I'll check tomorrow.

Someone-Else · Post by **Someone-Else** » Thu Jan 17, 2019 5:10 pm

(Quite) A few posts ago Kellys_eye asked how much current the solar panel was giving out, well............

: sunny day.jpg (379.64 KiB) Viewed 3736 times

: current.jpg (245.9 KiB) Viewed 3736 times

: voltage.jpg (195.39 KiB) Viewed 3736 times

So, as you can see, on a bright sunny day (Just before midday today) the solar panel is giving out 460mA and the no load voltage is 22.3.

But as I said, this is only a "will it work?" project and as we speak the light is on, but it only lasts for around 2 hours, but the other factor is how much sunshine is there where ever you are? (Not to mention how big is the solar panel / s you have.)

If you do try it, let us know. (I am also going to try different solar charge controller)

kellys_eye · Post by **kellys_eye** » Thu Jan 17, 2019 6:06 pm

Works out at just over 10 watts which is pretty darned good for a cheapo (10W I believe you said it was?) panel that is usually over-specced!

Should be plenty of energy to charge a battery. Even 6 hours would give a 12V battery enough charge to run the lamp for 4 hours.

Someone-Else · Post by **Someone-Else** » Thu Jan 17, 2019 6:15 pm

20 Watt panel (it was 10w lamp maybe it was that you were thinking of?)

Bear in mind that was in bright sunshine today, and that it is only running 1 lamp as it could not run 2 for very long. So I am going to say on a bright day maybe, but most of the time it has been overcast, and the 460mA was Peak, not constant.

kellys_eye · Post by **kellys_eye** » Thu Jan 17, 2019 11:00 pm

Well, the sun is low (in its defense!) but even so, I'd have expected a little more on a full sunlit day. Best check mid summer at noon in clear skies to get the best possible results from that panel but, in a way, I'm 'glad' you're not getting what you expect as that would be contrary to expectations given the 'cheapness' of the units.

Argyll · Post by **Argyll** » Fri Jan 18, 2019 9:19 am

I contacted the Ebay seller who suggested the solar panel I intend to install on the roadside cabinets should be facing south and at a tilt. It's not an option to install it on a tilt as this would leave a gap between the cabinet and the panel on one side which would allow moisture in. Plus the fact when's installed flat it's barely noticeable but if at a tilt it would be and i'd imagine some eejit ripping it off.

I'm calling him later to discuss.

Argyll · Post by **Argyll** » Fri Jan 18, 2019 9:55 am

SE apologies for hijacking your post. Sorry it was unintentional. I hope you don't mind?

Looking at these two products what are the differences? I can only see the second having a longer cable and battery clips. Are there any more differences I can't see?

https://www.ebay.co.uk/itm/302264050425

https://www.ebay.co.uk/itm/302262706953

kellys_eye · Post by **kellys_eye** » Fri Jan 18, 2019 10:43 am

One of those panel looks to be 'framed' as opposed to 'unframed' (to me). You'd want the unframed versions. Slap a load of Gorilla (or similar) double-sided sticky tape on the cell and it'll stick the the cabinet and it'll stick like sh*t to a bedsheet.

The output (of either system) is more than required to both run the electronics and offer additional extra charge for the battery - even at an acute angle to the sun. ISTR that the power output drop follows a sine curve of the angle of incidence i.e. at 45 degrees from perpendicular (to the sun) the output will be 0.707 of maximum (etc) - this doesn't account for low angles of incidence during winter months of course and, depending on location, you need to test to see if it works AT ALL in overcast/non-direct sun locations else you're wasting your time/money.

Depending on the time of year (and weather) the system may be 'crap' as a solution of 'great' but at leasty it would leave you free of time during a good part of the year.

It's certainly worth getting a purchase order for ONE system to do some static tests in the workshop/grounds of your office. The potential for time saving (and eventual cost savings) os very high. Your boss would be impressed.

Argyll · Post by **Argyll** » Fri Jan 18, 2019 10:51 am

KE good spot. I didn't see that.

Someone-Else · Post by **Someone-Else** » Fri Jan 18, 2019 7:18 pm

The first solar panel looks like mine.........flexible.

kellys_eye wrote:It's certainly worth getting a purchase order for ONE system to do some static tests in the workshop/grounds of your office. The potential for time saving (and eventual cost savings) os very high. Your boss would be impressed.

I did suggest that some time ago

someone-else wrote: The other thing is you must have a broken cabinet sitting around, or make a new one from timber, (identical size) buy a solar panel, battery, charge controller and one of your counters and stick it out side near your place and see how it does

Someone-Else · Post by **Someone-Else** » Fri Jan 18, 2019 7:24 pm

Argyll wrote:SE apologies for hijacking your post. Sorry it was unintentional. I hope you don't mind?

Its not me I am thinking of.

I understand your questions, and yes you have hi-jacked my post, but I feel that for future reference it would be better if this whole subject was split into your bits, and mine, so that (as wine~O has done) pointing anyone who asks about solar lighting can see just the lighting bits (and kellys_eye comments) but see nothing of powering a specific device. perhaps if you asked a mod?

Someone-Else · Post by **Someone-Else** » Sun Jul 05, 2020 5:26 am

It's well over 18 months since I started this project, I thought it is time to finish it.

: sp1.jpg (106.63 KiB) Viewed 2938 times

The solar panel is still there, the shed has a new door, I am still crap at woodwork, yes that is a (solar) lighthouse at the front of the shed, no it doesn't work. (It did for about a week)

: sp2.jpg (63.39 KiB) Viewed 2938 times

Here is the same solar controller and battery. I never changed any of the settings on the solar controller, so it's supposed to turn the light on when it's dark, and run the light for 2 hours and turn it off (Saves battery life and power) As then, I don't sit and watch the light, but I would say on a good day it runs for about 10 minutes (That includes the recent sunshine we had)

In very bright sunshine the solar panel produces around 13.8v (OK, it's dropped to that by the controller, as that is part of its job) but it is only there for only a short time, which is not enough to even partially charge the battery. As you see now (Its bright, so the panel should be producing power) I am only getting less than 11v. Its like this most of the day. So unless I have an "Umbrella*" of solar panels that's just how it is.

So the only conclusion I can draw, is as I always suspected* solar electricity is not feasible, even for the lighting a shed, unless you have deep pockets. (Despite what was predicted earlier in this thread)

* 4 Panels at the same angle, one facing in each direction.

* I have been running tests on a couple of solar water fountains, even when its really bright, nothing until the sun is in the right place, and even then a slight dwindle and the jet height goes down.

Someone-Else · Post by **Someone-Else** » Thu Jul 09, 2020 4:49 pm

Below you should see a video of the end of the solar panel debate. If you can't see it, refresh your browser.