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I have a plan ... Answered

I have acquired, as a strict one-off, a quantity of solar cells.

Apparently seconds that "work fine", the one I have unpacked is about 5 inches electrode-to-electrode, glass, and produces about 4-5V with no load in full sunlight. I assume the others are similar.

A plan springs to mind. A plan to save money and be "greener". I want to use them to charge batteries during the day, then light my home with LED sources.

A grand scheme, one that still requires the approval of She Who Must Be Obeyed, so I intent to take it is stages.

Stage One: The Shed.

I plan to install an LED light source, running off a battery charged by cells stuck to translucent panels already in my wall.

Questions:
  • what number and combination of (ordinary, cheap) LEDs would give a reasonable match for the brightness and colour of the currently-fitted 3-foot fluorescent tube?
  • Is this a suitable circuit to charge the battery?
  • Should I connect PV cells in series or parallel?
  • Is there anything I should have thought of?

Comments

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SacTownSue
SacTownSue

13 years ago

I LOVE this idea! I've often thought of doing something similar but I'm not sure about the math. If I'm not online then I'm reading or similar work that requires really good lighting. I guess "SHE" is wanting something esthetically pleasing. Under cab lights you don't have to worry to much how the look but I need them fairly bright. Please do an instructable when you have it figured out. I like that link lemonie. Those would be about what I need.

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Kiteman
Kiteman

Reply 13 years ago

Thanks - see the prices, though!

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lemonie
lemonie

Reply 13 years ago

You should be able to do this cheaper eh? L

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Kiteman
Kiteman

Reply 13 years ago

Cheaper than 9 LEDs in a strip for $48? I should coco! I would like to use cheap (pennies-each) RGB LEDs, powered from a 12V lead-acid battery, charged by the solar cells. I have an idea that 6 PVs (paired in parallel, three lots of two) should be enough to charge the battery (which I haven't got yet), then I can run 12 LEDs (in parallel pairs again) from the battery. Assuming that all three colours of LED are similar brightness, four of each will average-out as white-ish.

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lemonie
lemonie

Reply 13 years ago

I was thinking of this: found some LED Christmas lights today. You'll need 12+ volts to recharge a lead-acid battery, So I'd go with 2 banks of 3. But how much current do you get out of them? According to the link, 138 LEDs give an output equivalent to 50W, @ 8W, that's ~0.67 A at 12V. If you assume that you'll get a many hours of sunshine as hours use of the light, you'd need to be getting over 0.5A out of the cells(?)

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Kiteman
Kiteman

Reply 13 years ago

Looks like I'll have to connect them to a load and measure the current as well.