Solar panels that produce electricity, known as PV panels, are becoming a consideration to more people as a way to supplement their electrical needs, or in some cases produce all the electrical power they need for their home. After a little research it becomes evident that deciding how many panels will be needed is one of the first in a list of items you will need to figure the cost and other requirements for a project such as this.
First of all you must find how many watts per day your home uses, or the portion of your home that you want to supplement with electrical needs. If it's your complete home and if you are now living there, you simply need to look at your electric bill and see what you use on average every month. Notice that your usage is probably in KWH (kilowatt hours), which is using 1000 watts for one hour. If you just want to provide power for part of your home you can figure the wattage and how many hours you expect it to run per day and base your system needs on that figure. You can even find the wattage used by individual appliances by using a meter which merely plugs in between the wall and the appliance.
Once you have a rough figure in mind for your needs you will need to design a system that can produce that much power on a sunny day. Bear in mind that power from solar panels varies by the available sun in a day, so your needs will have to be somewhat flexible, also. Panels are listed as to their output wattage, so you will want to put enough of them in array to achieve the desired power level. The other components of the system will also need to be sized accordingly so that all the parts work together to supply your needs both day and night.
Other components of the system are wiring, an inverter which will change the DC voltage coming from the panels to AC voltage that your home can use, a controller to police the system automatically, batteries to store the required power and possibly a switch to tie your system into the power companies lines if necessary.
There are many companies who will engineer the entire solar power system for you and recommend the proper components, and by the same token there are many resources online that will help you learn what is needed. Even if you find a firm to engineer your system there may not be anyone close to you qualified to install it, so it's good to understand what it will take to make the whole package come together. It is also possible to purchase the parts where ever you like and build the entire system yourself, including building the solar panels yourself.
