# How Much Solar Power? Determining How Many Watts Your House Needs

If you’ve decided to add a system of photovoltaic solar panels to your home or business or established that it is time to expand an existing system, the next question is: How much wattage I need

[19459002?] For this to find out, you should know how much power you consume (or how you plan to consume, for new construction or additions that will require a lot of power – as a woodworking shop or a hot tub), and how much sunlight you receive throughout the year.

Another way to increase the number of hours of direct sunlight you receive is estimated to assume a value or use a rule-of-thumb. Often five hours of direct sunlight on average expected for the year. Although this is a fairly generally accepted, you might end up disappointed if your solar system generates less power than you expect because you have fewer average hours of sunlight than this.

A third method is to look at an average regional value. The Florida Solar Energy Center presented a study in August 2004 on the ACEEE 2004 Summer Study on Energy Efficiency in buildings called “geographic variation in the potential of Rooftop Residential Photovoltaic Electric Power production in the United States.” This study simulated the generation of a 2 kilowatt (kW) system for photovoltaic roof 236 sites in the United States. Depending on location, they found that these 2 kW system on the roof between 5 and 8.5 kw-hr would generate on average per day during the year.

Using the general rule-of-a 2-kw system receiving direct sunlight for five hours a day would be expected to generate 10 kw-hours on average each day throughout the year. The study of Florida, the same system would be expected to generate only five -. 8.5 kw-hours a day throughout the year

How you proceed depends on your goals. If your goals are to offset your electricity costs, it is one of the approaches will provide an estimate of the number of hours of direct sunlight you receive. However, if your goal is to become energy independent, then the use of the results of the simulation Florida, a more conservative value that would provide more chance of a system sized for your needs. Take the results of the simulation and a few of your own observations (if you have a lot of tall evergreen trees on the south side of your house that a majority of the winter sun, etc. Block) and you should be able to estimate number hours of direct sunlight you receive.

For example, if you decided to average current consumption value used and you 600 kw-hours use per month and your billing company does not report the number of days in the billing cycle (assume 30 days per month) than you consume 20 kw-hour electricity (600 kw-h divided by 30 days a month). About 3.5 hours of direct sunlight per day using the Florida simulation data and assuming you live in western Kentucky, you will receive (from the graphical estimating a value of 7.0 kw-h divided by 2 kw – study is based on a 2 kW system). Then your system should be sized to approximately 5700 watts.

Source: http://ezinearticles.com/?How-Much-Solar-Power?-Determining-How-Many-Watts-Your-House-Needs&id=1744092 by Daniel Peplinski

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