Installing a Solar Energy System for Your Home

This article covers the installation of a solar energy system for your home. I'll take you through a process that includes 1) doing an energy audit of your home to see how much electricity you consume, 2) ways to reduce your energy consumption, and 3) installing a system.

Installing a solar energy system for your home is not cheap and the payback can be anywhere from 7-15 years. It's important to understand what your electricity consumption is, how much electricity you could produce with a solar energy system, and how large an investment will it take to install a system.

Perform and Energy Audit of Your Home

It is important to determine how much electricity your home consumes over time and also to see what items in your house are consuming the most electricity.

To do an audit of your electricity consumption, determine how much electricity you consumed, per month, over the last 12 months. Then, determine the consumption of individual items in the house. One easy way to test individual appliances is to use a portable meter, such as the P3 Kill A Watt (see image), where you plug your appliance directly into it and it will tell you how many kWh it is using.

Another method, albeit a more difficult one, is to use your household utility meter. If you have an older-style model with a rotating disk, you can calculate the the change in consumption, by the change in rotation speed when you turn on the appliance you are measuring. Take a few different readings at different times to account for other appliances turning-off-or-on, such as your water hear, in the house.

Accoring to the U.S. Department of Energy, the typical household consumes 11,000 kWh per year, or 917 kWh per month.

Reduce the Electrical Load (consumption) of Your Home

Now that you know how much electricity your are consuming, set about to reduce your consumption, or electrical load. This is important, not just for the direct and immediate savings since you reduced consumption, but more importantly, it may reduce the cost of your solar energy installation, because of less electrical demand. A drop in consumption will save you ~$100 a month, but a cut in your installation cost, will save you thousands!

Lights are a big consumer of electricity, particular halogen lights. Look at each light and consider replacing it with a flourescent light. A flourescent light generally consumes 80% less than a halogen light. Of course a halogen is very bright, so the replacement might not be a perfect substitute, but you will have achieved your goal of  a reduction in your electricity consumption.

Electric water heaters are nice, because they give you stand by hot water all the time. Consider putting the heaters on a timer that shuts them off a set times each day, say during the night. You'll still have hot water in the tank, but it'll reduce the number of times the heater turns on to heat the water. You'll have to test this, because your usage patterns will dictate how much of a savings you can achieve.

Other items that are big consumer of power that should be assessed for reduced usage are: spas-pump and heater (this is a huge consumer), air conditioners, ovens, pool pumps (they don't have to be run 24 hours a day!), washer and dryers, floor heaters (maybe wear a sweater more often?), and incandescent lights. More Department of Energy information on appliance electricity usage.

Once you have completed your consumption reduction exercise, calculate what your new average electrical load is. Compare this load to your original electrical load, determine the difference and then apply this difference to the monthly consumption your incurred over the last twelve months. You should be able to see what your peak and average demand.

Determine the Size of the Solar Panels

Typically, you'll put solar panels on your roof. It's area that you don't need and it's also more out-of-sight than putting them in your front yard. Also, the slope of your roof will also be utilized as the more perpendicular the angle from the sun, the more efficient your system.

Let's assume that we have 1,000 square feet of root to use for our solar panels. A typical panel will produce 14 watts per square foot, so our 1,000 square feet could produce 14 kilowatts (kW). Converting the D.C. electricity with an inverter from your solar panel to A.C. results in about 10-15% of loss. So at 15% loss, we can now produce about 11.9 kW. We then need to determine the number of peak sun hours we can expect in a day. It'll average between 3.5 (Northwest USA) to 6 hours (Arizona-Nevada) per day, depending on where you live. In this example, we'll assume that we'll get 4 hours of total peak sunlight, which would be 47.6 kilowatt hours of electricity (kWh) per day.

Installation of the Solar Energy System

Now it is time to install the solar panels on your roof. An installer will usually come out and make an assessment of where best to install the solar panels. One very useful tool they may use, is the Solar Finder, which can determine the location and angle of the sun at different times of the day, and at different times of the year. It is very helpful in determining whether there will be a tree in the way of the sun!

Shade is very important to consider in the design of your solar energy system. One tree covering just 10% of your panels, could reduce electricity production by 40%! Cloud cover is also important, but no where as important as shade. Clouds can reduce production by 10-20%. So in effect, on a sunny day, you could be producing less power than a cloudy day, if you simply have one tree covering a portion of your panels. So make sure your panels are placed away from shade!

Request from the installer an estimate of electricity production based on its ultimate configuration. This will give you something to compare with once you do have it installed and have actual production. Installation is usually no more than 2-3 days.