I've spent my entire life living on or near the Gulf Coast. And even though we've had a couple of seasons with no major hurricanes, I can't help thinking about them this time of year. Of course, the big storms are very dangerous and most people should evacuate to safer ground. But those who stay and those who return afterward, are often faced with a loss of electrical power. Even some relatively minor storms can cause power outages.
Power outages suck! Sure we have candles, lanterns, and flashlights, but you have to either station these items in each room or carry them around with you. I was trying to think of some way to have lights in every room of the house in the event of a power outage and, naturally, solar came to mind.
I would love to outfit my house with a complete solar system that produces 5 or 10 kW of power, but I'm not quite ready to make that investment. So I needed a quick, easy way to have lights all over the house, plus the ability to run other small devices such as fans and a couple of phone chargers.
I was walking around my house from room to room thinking about this and it hit me; phone jacks! Even though I haven't had a landline phone in years, there are phone lines run throughout the house and a handy little wall jack in each room. Why couldn't I use this wiring to provide low voltage solar lighting in the event of a power outage?
Well, the first reason is I didn't know if I could legally disconnect the wires inside my house from the phone company's junction box outside. So I called my local phone company office and asked. Turns out there's a customer disconnect right there on the side of the house. They said I can disconnect my house from their line and everything on my side is my property. Awesome!
The second reason is the wire size. Typical phone cables are between 22 and 26 gauge, which means the current capacity is very limited. But I did some research and found that there are all shapes and sizes (and wattages) of 12 volt light bulbs out there and the LED bulbs come is sizes as low as 2 or 3 watts.
Based on the information I found at http://www.engineeringtoolbox.com/wire-gauges-d_419.html I should be able to safely run 3.5 amps through a 24 gauge wire. At 12 volts, that comes to 42 watts. However, since I don't know the length of the wire in the walls, I decided to play it safe and keep it to a maximum of 2-3 amps, which still gives me 24-36 watts to work with.
So I decided to configure a low-end solar system using mostly items I had on hand or could buy locally. What follows is a detailed description of this project. I hope you like it!
UPDATE: I added an inline fuse between the charge controller LOAD (+) lead and the phone line just in case somebody plugs in too heavy a load.
UPDATE: Due to lots of helpful suggestions (and a few outright warnings) regarding my choice of a 110 volt plug for the power outlet, I decided to add some optional 12 volt outlets to the project. Please see Steps 1 & 3 for details.