![]() 12V is not considered a shock hazard, but FIRE is your enemy with low voltage power systems because of the high currents involved. A grid-connected solar PV system does not give you resilience against power cuts, because the anti-islanding systems in the grid tie inverter shut the system down if the main power fails, so that a PV system does not send power back into the grid when it may harm power workers trying to repair faults.ġ2V systems have different safety issues from 240VAC mains circuits. ![]() That sort of thing is on a different scale from this project, and capital costs are usually in the order of several thousand pounds, but the energy savings are much, much greater. For that it is best to get a grid-connected solar power installation which will allow you to save energy and get renewable feed-in tariff payments. If you want to primarily save energy or reduce your carbon footprint using solar power, this is not the solution. That is because in the summer you get far more solar energy and you’ll probably use the lighting less. In the summer you can also run a laptop computer power supply independently of the main for a couple of hours (these run typically 40W). The system as described lets you run one or two 12V 1.8W LED lights through the year – my system was able to run mine through the winter and the shortest day where the light would be on from about 6pm to 11pm. Although I have used lighting as an application, such a system can run an electric fence for much of the year if suitable solar panels and battery are used. It can be used at home to keep lighting during power cuts, but the same principle can be used to provide power to sheds on allotments, outbuildings or island sites without mains power. This project lets you run lighting off of solar power, effectively storing sunlight for later use. This was originally published on TI’s website, which is no more. It had to be targeted at a competent DIYer, and is for small scale lighting. The idea for the project came from the Transition Ipswich Energy group in 2011. Total costs should be in the order of £100, but there are ways to reduce that by getting some items from Ebay. In summary, I’m running < 1/8 the rated AC voltage as DC through the switch and I’m well under the max Amp rating of the switch.This project is about resilience more than energy saving, though it can also be used to save energy. High voltage DC will arc a lot compared to the same voltage as AC, which, over time can damage the switch possibly leading to component failure of the switch. By keeping the voltage low there is little chance of arcing during the disconnect of the circuit under a load (the LED bulb). The low voltage (I’ve heard that the rule of thumb is to run no more than 25% of the AC rated voltage through a DC wired switch) in addition to each LED using < 0.5 Amps means that there is little chance of overwhelming the circuit. I used a three switch AC standard light switch – which, while not rated for DC current is perfectly capable. ![]() UPDATE (8-26-2011): I’ve had some comments about what kind of switches were used for the 12V DC lighting and some one noted that I have toggle switches in the schematic, however that is not what I used. Each bulb puts out 330 lumens at the cost of 4.6 Watts. The total draw of two lights and an active motion sensor is only about 15 Watts. With solar keeping our battery bank at full, the LED lights are left on pretty much all the time. The 4th light shines on the cabin and baths it in a pure white light visible from the edge of our land. The 2nd and 3rd light team up with the motion sensor off the front (12 min duration, 100% sensitivity, enabled for dusk and nighttime). The 1st light illuminates the workbench and window. With all of the wiring completed, there were only two boxes to be installed. The Sonicrafter was the perfect tool for cutting through the thick siding while leaving the OSB underneath intact. Tomorrow I’ll cut and install the motion light double fixture and the single fixture over the service door.Īfter breakfast we assembled the rest of the LED system. By night’s end everything was wired including the fuse holder. I ended up cutting the opening for the triple light switch as well as a single 12v light fixture over the work bench, and then installing and wiring them both. I set out with the intention of installing a piece of wood that cover the 1” opening of the 12v LED lighting line that runs up the wall from the bus bars to the a triple light switch near the service door. After a pasty I headed out to the garage to tinker.
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