Smaller-scale solar

JetMech

Now that I've learned that solar is a better way to start out, I had an idea. Thanks to a neighbor's tree, I'll be building a new shed this spring. It gave me an idea to try out some of the solar shingles that are/will be available. I'm assuming it would be possible but thought I'd check here first. If I run X amount of those shingles, could I use them to light a bunch of those 12v yard lightsthat you stick in the ground? I would have to store the power in a few batteries during the day and perhaps use a dusk/dawn sensor to turn them on and off. Does this sound feasible?

lamplight

Re: Smaller-scale solar

Hi Jet

yes thats totally feasible, the specifics of how much pv wattage and battery amperage you need is not my strong point but youd want to start by finding out how much power (and how long you need em to run) you need so looking at the exact lights you ant to get is step one.

in case you dont know, the shingle integrated PV is alot more costly than getting pv panels, but depending on how many lights you need you might not need much (either way).
-Matt

JetMech

Re: Smaller-scale solar

Probably a max of about 30 lights. I have to see what my choices are, hopefully there are LED ones available. I've tried the solar individual lights, but the sun isn't available in some of the places I want to put them. I'd rather stick with the wired ones and power them from a common solar unit. Thanks, I'll start researching lights.

icarus

Re: Smaller-scale solar

Pretty simple to do, but "do the math"

Figure out how many lights, how much they draw, how long they will be on etc.

Then calc. how many day(s) reserve you need, that will give you battery size and PV capacity needs. A lot of the low voltage lights are NOT very efficient, that is they have halogen bulbs. You might look to use some LED type lights.

Icarus

lamplight

Re: Smaller-scale solar

yep,
then you can use one of these to control the lights AND charge the batts (i have this same one on a tiny 10watt solar panel for night lights in our kitchen , basicallt the same system you want to design outside)
http://store.solar-electric.com/c12.html
(they sell them here at northern az wind and sun online store too, that was just my first search result)

JetMech

Re: Smaller-scale solar

Well so far all I can find are spotlight LEDs in 12vdc. The Malibu-type lights are all 12vac. I did find LED replacement bulbs for the Malibu lights though. But still, I need 12vdc lights to run off my planned solar setup. Any ideas?

n3qik

Re: Smaller-scale solar

Give us a link or something on the light(s) you are looking at. Then we can see what type of bulb they use.

JetMech

Re: Smaller-scale solar

Here they are. The CL191 model. That doesn't give much info, but the 11W replacement bulb number is ML11W4C.

n3qik

Re: Smaller-scale solar

They look like 194 automotive wedge bulbs, if so, try eBay. Do a search for "194 white led"

Quick find:
http://cgi.ebay.com/ebaymotors/194-168-158-5-LED-Lights-White-2-Bulbs-Tail-Plate-Trunk_W0QQitemZ360019061945QQcmdZViewItem?hash=item360019061945

JetMech

Re: Smaller-scale solar

Cool. So I could get a set of those lights, swap in those (or similar) 12vdc LED bulbs, and then I could supply the string with 12vdc instead of 12vac. Thanks!

Solar Guppy

Re: Smaller-scale solar

While the LED are better power wise, there is no difference from a incandesant bulb ( in your example Malibu ) in using AC or DC. The typical garden lights are AC as it cheaper from manufacturing the power pack ( no electronics are needed, just a transformer ) but the bulbs work exactly the same off either AC or DC.

JetMech

Re: Smaller-scale solar

Interesting, I didn't realize that. It makes sense though. But like you said, the LEDs would consume less power.

n3qik

Re: Smaller-scale solar

By using 12 AC with a LED lamp you may see a slight flicker and it may be not as bright.

mike95490

Re: Smaller-scale solar

Remember, LED's are a current operated device, and require a limiting resistor somewhere to prevent them from burning out instantly. "12V" automotove drop-in bulbs have this resistor, but it's upper operating limit is 13.8V or so, standard vehicle voltage. If you replace a bunch of lamps, and still use the transformer, remember the transformer will be unloaded, and you will see peak voltage, close to 18V, which may exceed the Peak Reverse Voltage of the LED's . Check the unloaded transformer with a decent meter before adding LED bulbs.
12-13.8VDC should be fine.

n3qik

Re: Smaller-scale solar

Good point Mike, I was going by he was running of battery. If you do get the lights first, then get a 12vdc 200w regulated power supply. This will supply you with 30 lights at 6w each. If you got with the 11w reg lights then you will need a 350w power supply.

System2

Re: Smaller-scale solar

Huh...I wondered why my LED nav lights cut out when the battery got really low. Now I know why.