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Central SELV solar lighting?

Posted: Tue Jun 16, 2020 10:43 am
by FrontSideBus
Been thinking, garden solar lights that each have their own PV cell and battery. Some might be in the shade ect and not get a full charge, or the batteries may wear out or the switch go rusty.

I wonder how hard it would be to set up a proper nice big PV cell on the conservatory which charges a nice big heavy duty battery in a central point and then just modify all the solar lights to run off that?
Being SELV, you could just use normal arctic cable buried in the ground too.
Thoughts?

Re: Central SELV solar lighting?

Posted: Tue Jun 16, 2020 10:53 am
by Oliver
Solar charge controller, 12v battery, photocell and solar panel. Output of the solar change controller connected to a photocell and DC to DC boost converter that is set to a lower voltage for the LEDs.

Re: Central SELV solar lighting?

Posted: Tue Jun 16, 2020 11:11 am
by FrontSideBus
That's exactly what I'm thinking but I'm just wondering if it would be worth it...

Re: Central SELV solar lighting?

Posted: Tue Jun 16, 2020 12:34 pm
by Oliver
If you are just wanting the lights for decoration go for it but if you are wanting useful light, just use some mains lights like those fluorescent spike lights.

You can actually get 12v lights that looks like solar lights.

Re: Central SELV solar lighting?

Posted: Tue Jun 16, 2020 5:32 pm
by Slyspark
I guess it really comes down to if you can be arsed to dig the trenches for cables if you don't want them to get damaged, or, if you're happy to have them just under the surface (might them get damaged) or on the surface where you can see them, but then obviously looks crap? I mean, no reason at all why you can't do this, probably be far more reliable, etc.

The other thing would be the expense. If you have the panel / battery / controller, etc already, then nothing lost in doing so, but given how cheap stand-alone solar lights are, is it worth a large expenditure (for something decent) to do this?

At the end of the day, entirely up to you and it's a nice idea....

Re: Central SELV solar lighting?

Posted: Tue Jun 16, 2020 6:34 pm
by FrontSideBus
Mainly one of things I fancy doing "just because I can" :D

Re: Central SELV solar lighting?

Posted: Tue Jun 16, 2020 7:29 pm
by Slyspark
Then you should probably do it :)

Re: Central SELV solar lighting?

Posted: Mon Jun 22, 2020 9:55 pm
by Ash
More than 10 years ago i made something similar, but not quite

The energy source was a wind turbine, not solar. The turbine was based on a large PC fan (iirc it was 120mm or so). I removed the stepper driver chip inside and put bridge rectifiers off the winding leads

The fan was connected into a funnel that concentrates wind from a square of 4x4ft into the fan

It would spin for a little whenever there is a small gust of wind, but not move (stand on a magnetic "position") from very slight air movement. So maybe larger fan is requierd to catch weaker air movements

The energy storage was several 10000's uF worth of Electrolitic capacitors, charging at the fan output voltage (single volts)

The garden lights were homemade, out of the cones from the top of plastic water bottles, sealed with section from the side of the bottle and a foil reflector. Inside were just 5mm LEDs. They were wired with inner wires from CAT5e, shallow buried in the mud

On nights with gusts of wind the lights would brighten up as the wind blows, and drop and dim down as it ends. (The Blue LEDs would go out first as the capacitor voltage goes below 3V, and Red LEDs stayed the longest)

Thinking of it now, the most performance was lacking in the turbine. Bigger fan that spins more easily (without the magnetic "stops at positions" that some fans have more pronounced than others) would work better. A more efficient rectifier, made of Schottky diodes and using doubler configuration (to minimize diode drops) would allow more efficient operation. Current regulated PWM controllers (the circuit that's in ordinary solar lights...) could use the capacitor charge more uniformly, so provide longer lighting periods after each gust of wind