Don Vandervort, Head Homeboy, has written more than 30 DIY home improvement books, been a segment host on HGTV, served as MSN.com's home improvement expert and written countless magazine articles.
When you go shopping for the photovoltaic (PV) cell system that is right for your home, there are several things to keep in mind:
Output How much juice does your home need? If your power bill breaks down the amount of electricity you use on a 24-hour basis, you can easily determine how many watts your PV array will have to generate in order to satisfy you home's needs. If not, during peak hours of the day when the sun is highest in the sky and the PV cells can operate the most efficiently, output can range from 40-watt models all the way up to 200 watts. The difference generally is in the technology, size, and price.
Dollars per watt Another way to gauge the cost of purchasing PV cells is to look at the dollars-per-watt cost ratio. A rough estimate would be to shop for modules that are priced in the $4 to $5 per watt range. This means that if the module has a maximum output of 100 watts it would cost $400 to $500. Using this method of calculation, you can roughly determine how much you would need to spend to power your home.
Insolation Insolation is the term used to measure the amount of direct sunshine that falls on a square meter per day. It is rated in kilowatts and will help you determine how much energy you can expect your PV array to produce in your region.
Mounting In North America, is it critical that your array have direct southern exposure and the proper tilt to ensure maximum efficiency. There are several kinds of solar array mounting systems for the home, and picking the right one is critical to getting the most out of your investment. Directly installing the PV modules flat on your roof may be the most aesthetically pleasing approach, but it will reduce the amount of power generated during low-light and cloudy days (yes, PV cells even work in the rain, they just generate less electricity.)
Mounting on a stand may be more practical, especially if your home has a flat or unusual roof. Some module mounting stands come with sensors and motors to automatically turn and tilt the PV cells to follow the sun across the sky and capture the most energy possible.
