If you are thinking about installing a residential solar energy system in your home, you will need to know your current energy consumption. Usually, you can get this information from your local utility company. Using this as a basis, you will be able to design your solar energy system to fit the needs of your house. The climate in your region will have an impact on energy use, as will the direction your windows face, the number and location of trees on your site, and the types of appliances you own. Even the kind of light bulbs you use can make a difference.
The yearly temperature extremes in the geographical region you live in will be a big factor. If you live in an area with temperature extremes in winter or in summer, you will use more energy to heat or cool your home than if you lived in a moderate climate.
South facing windows in a cold climate can help lower your heating bills. North facing windows in a hot climate can lower cooling bills.
Mature trees can provide shade and help lower cooling bills during the summer, while the bare tree limbs allow sunlight in during the winter months. All of these factors contribute to your overall energy use. And installing energy efficient insulation in walls, roofs and floors help reduce utility bills in all climates.
If possible, convert all of your appliances to energy efficient models. Newer appliance models often use as much as 50% less energy than older models, especially if they need repairs and are not working at top efficiency. Changing to compact fluorescent light bulbs also makes a substantial impact on reducing electricity consumption.
After evaluating your house for these factors, you can plan to build a solar photovoltaic system by multiplying your average daily kilowatt hour usage by about .25. This should give you a rough estimate of the daily kilowatts your solar panels will need to generate in order to supply your current electrical needs.