Simple solar circuit

laurel7172

Hi there. I don't know if this belongs on the techie thread, but it seems to me that the expertise is on here.

I work in Year 6 of a primary school, and I'd like to have a small backlit corridor display (basically a few strips of movie film in a lightbox). Not wanting to burn through batteries, I'd like it to be powered by solar cells...without spending a fortune.

If I were to buy a couple of these:

http://www.ebay.co.uk/itm/OPL15A25101-90x50x3mm-1-5V-0-37W-Solar-Cell-Renewable-Energy-Module-550010-/120984733792?pt=UK_Gadgets&hash=item1c2b408860#shId

is it just a question of connecting them up like batteries to a bulb holder...and what would you say the maximum length of the wire between panels and bulb should be? It's a dark corridor. I can mount the panels on the far side of an internal window quite easily, which would put them on the darkest side of a room with large windows, but direct sunlight would require wiring of perhaps 20 feet. Is this likely to work?

Thank you.

Dave_Fowler

laurel7172 wrote: »

Hi there. I don't know if this belongs on the techie thread, but it seems to me that the expertise is on here.

I work in Year 6 of a primary school, and I'd like to have a small backlit corridor display (basically a few strips of movie film in a lightbox). Not wanting to burn through batteries, I'd like it to be powered by solar cells...without spending a fortune.

If I were to buy a couple of these:

http://www.ebay.co.uk/itm/OPL15A25101-90x50x3mm-1-5V-0-37W-Solar-Cell-Renewable-Energy-Module-550010-/120984733792?pt=UK_Gadgets&hash=item1c2b408860#shId

is it just a question of connecting them up like batteries to a bulb holder...and what would you say the maximum length of the wire between panels and bulb should be? It's a dark corridor. I can mount the panels on the far side of an internal window quite easily, which would put them on the darkest side of a room with large windows, but direct sunlight would require wiring of perhaps 20 feet. Is this likely to work?

Thank you.

I'm sure you realise that the power from the solar panels would only be present during sunlight hours. So unless you use them to charge some rechargeable batteries, the power to the display would only be present when the panels were lit by the sun.

From the ebay description, the power rating of each panel is 0.37W. This I assume is when the panels are in full sunlight. In a simple circuit two panels in series would provide sufficient voltage to drive LEDs in parallel. The maximum current from the panels would be a little over 200mA. This is enough for 10 standard 20mA LEDs.

During summer months you could use the solar panels to charge batteries so that more LEDs could be lit for, say, 6 hours a day. The batteries would charge when the LEDs are not lit and they would discharge and help the lowish current from the solar cells during the rest of the day. In Winter, not really enough power from these small panels to hope to light more than 1 LED - if you're lucky.

Dave F