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A friend of mine did something similar. He put in a small solar array with only 3 panels, an inverter/charger, and 400 Ah of 12-volt batteries. This DC then fee
by 205guy 7y ago
A friend of mine did something similar. He put in a small solar array with only 3 panels, an inverter/charger, and 400 Ah of 12-volt batteries. This DC then feeds into a breaker panel and goes to lights in all the rooms. He uses LED spotlights, the little bulbs that plug into wires stretched across the ceiling. He said he just ran 10-gauge Romex wires through the attic, down to DC-rated switches and then to the ends of the cables.
He still has all the original 110 wiring and fixtures in the house, but this battery-backed solar system runs all his lights. It can easily go 2 days without sun before he needs to use the regular lights. Another benefit is that DC LED bulbs are by definition flicker-free, and also low consumption (4-6 watts each) but bright. He calculated he can light each room better than before with 6-8 bulbs, so 40-50 watts, thus only 4-5 Amps (@ 12 VDC) to each room.
All the big appliances in the house still run off of of AC, but he does have a 110 inverter so that he could run a critical appliance such as a fridge during an extended outage.
So this little system replaces 1-2 kWh of incandescent lighting per day (CFC or LEDs on 110 would be less, but not flicker-free), while providing lights during outages. He says it's not cost-effective (the usage displaced by solar and battery usage doesn't cover the cost of the system), but the backup powers is worth it to him.
- holoduke 7y agoI am actually thinking of something similar. Instead of 12v DC I probably would go for 48v or maybe even higher. With 12v your cables soon start to become too thick to be practical if you want to run serious things like garage doors / window shades etc.
- 205guy 7y agoMy friend said he picked 12V because that's what the easily-available LED bulbs are rated at, and he just wanted a simple lights-only system. I guess you could pick whatever voltage you want for your loads and cable runs, but you need to have the appliances you want available (or easily DIY) in that voltage. It would probably be possible to convert down the voltage once, but any more than that and you're introducing loss again.
- Maakuth 7y agoOn the other hand, you could connect 12V lights in series to get them the desired voltage.
- Scoundreller 7y agoThat’s not always a good idea. It is putting more current through each light. And particularly problematic if each bulb has parallel LEDs and they start burning out: then more and more current is put through the remaining LEDs.
- Scoundreller 7y ago120VAC LED lamps will just rectify that 120V to DC and then use a power supply to drop it to around 30V. In other words, a 120VAC LED should work just fine on 48VDC with the same output. It’s also explains why they don’t dim. (Obviously avoid the dimmable ones in this application!)
- sebazzz 7y ago> Another benefit is that DC LED bulbs are by definition flicker-free, and also low consumption (4-6 watts each) but bright. You still need PWM to control brightness, no? I'd you're using resistors efficiency goes down a lot.
- manicpolymath 7y agoSure, but if starting with DC you can pulse on the order of hundreds if not thousands of Hz instead of 50/60Hz, which shouldn’t be noticeable.
- mrb 7y agoYou can find 120V LED lighting that is flicker-free, eg. anything sold under the Philips brand (in my experience).
- hadlock 7y agoOur Philips brand 120v AC LED lighting runs about 10watts per, is flicker-free. It's not 6W but I think that is largely due to the higher light output at max brightness (~800 lumen). Also has the advantage of using existing wiring. Integration with the voice assistant software and color modes has been a nice added benefit (ignoring privacy stuff). 12 volt wiring in homes isn't terribly efficient as once you get past 6-10 feet you need really expensive (heavy, thick) wires to not have much voltage drop. Most new boats use 24 or 48v for long haul and then local step down to 12v where needed (kitchen, living, sleeping areas etc).