With all the hype surrounding global warming, it seems renewable energy installations may start to become more prevalent in the near future. As someone who is interested in playing with all things technical, I thought I'd have a bash at making my own renewable energy source to see if I could run a few things from the power of the sun.
The idea is that the solar panel will convert sunlight into electricity which will charge a battery. Various loads can then be run from the battery (day or night). So long as the sun pops up in the morning to recharge the energy that was taken out, the cycle should be able to continue.
I'll start this article with my conclusion - don't assume something like this is going to save the planet or your wallet any time soon. I approached this project as a piece of fun as messing around with electrical oddjinks is my hobby, but if it's not yours, it may not worth the effort. Here are some hard facts:
A single solar panel is enough to run a few small items but it doesn't take too many overcast days in a row to limit its effectiveness and lets face it, the UK isn't known for it's long hot sunny days. With my installation, an evening of running one or two lights can easily sap more than a days worth of charge from the battery if the day has been particulally dark and overcast. With several dark days in a row I can watch my battery charge indicator start to drop quite quickly.
There are limitations to what you can run off such a battery. Don't expect to have your washing machine and dryer powered off it. The battery also puts out a different type of power than most devices use - 12V DC instead of 240V AC. Standard household equipment won't work without conversion or an inverter (which changes the 12V DC into 240V AC for low power mains devices). Those overcast UK days and long winter nights may also be a challenge for an overworked and undercharged battery.
My installation is just a small and relatively cheap one because I wanted to play with the technology and see what I could do with it. If you have enough money you can go for a 'proper' installation, covering your whole roof in panels and generating enough power to enable you to live off the grid. I don't know that such an investment in the grey-UK would be justified, however there are plenty of American websites detailing such installations under sunnier skies. Even then, because of the cost you're probably looking at ten years or so before you've made your money back and can truly enjoy the benefits of free electricity.
Another important thing to note is the effort that goes into the manufacture and installation of the component parts. It's all very well claiming to have a renewable energy source pumping out free electricity, but you have to maximise the effectiveness of your installation to try and offset the negative impact of the manufacture, packaging and transportation that all went into making the panel, battery, cables, bulbs, etc. Also, the batteries don't last forever. My battery is rated at 200 cycles at 60% DoD which means I'll eventually have to replace it.
So, bearing in mind that this project has been undertaken out of interest rather than out of any real practical measure to reduce the 'leccy bill or save resources, it is time to begin.
Because of the size and complexity of this project, I have split it into several chapters...
Chapter 1: Introduction (this page)
Chapter 2: Parts
Chapter 3: Installation
Chapter 4: Conversion of existing equipment
Chapter 5: 240v Inverter
Chapter 6: Timer Control
Chapter 7: Practical ways to save energy
Chapter 8: Updates
Update: Radio Clock
Update: One Year On...
A renewable energy project such as this can be as easy or as complicated as you like. I'm never one for making life easy so I have some ambitious plans for my renewable energy installation which includes such delights as converting existing equipment to run from low voltage, wiring special sockets around the house, using an inverter to ramp the energy up to 240V for some low power mains applications, installing a control panel to monitor the status of my installation and using a bodged thermostat timer to control external lighting. This need not be the case for all installations and it is possible to buy off-the-shelf solar kits for smaller needs such as remote shed/garage lighting which are comparitively simple to install.