Posted: 3/10/2013 6:46:10 PM EDT
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I bought a couple sets of the harbor freight 45watt solar panel kits before I knew they really weren't a great deal. Now I want to put one of them to good use. I have an out building I would like to put quality motion detecting lights on it. I want to see what is available in a LED spot light and how many units I can run off 45 watts of panels and how many amp hours of battery I will need.
Hopefully I can run three separate lights on the same system. My biggest concern is figuring out a way to avoid over discharging the battery if the sun doesn't come out for a few weeks. |
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I've considered 12 volt PIR lights several times, and always ended up at the conclusion that using a small inverter to power conventional 120 VAC PIR floodlights was a better way to go, for several reasons:
1. Compared to a good pair of 120 VAC LED floodlights, the light output from most 12 volt security lights is pretty wimpy. 2. One inverter and 12V battery can power several fixtures - and adding more fixtures is cheap and easy. 3. There is a wide variety of LED and CF bulbs available nowadays, in various PAR bulb formats - Makes it easy to pick the right bulb for the job. 4. Most inverters already incorporate a low battery voltage shutdown feature - no additional circuitry required. 5. Using 120 VAC greatly reduces voltage drop over long wire runs. In some cases, it more than compensates for the inverter's electrical inefficiency. 6. Some 120 VAC PIR fixtures draw a surprisingly small amount of power when they're idle - Typically, just a small fraction of a watt. |