When installing PhotoVoltaic (PV) panels on the roof of a house or on a pole mounted array, a variety of factors need to be considered. One of the most vital is shading. Since PV panels consist of various cells connected together in series, if even one cell is shaded it can not only shutdown an entire series of cells around it (even though the others are receiving full sun), but can really turn out to be a current drain on the entire system!

The amount of luminosity the PV panels are exposed to is also a major factor. It’s obvious that latitude and prevailing cloudiness are the most significant factors. Two solar power arrays installed at exactly the same latitude, say Seattle and Spokane WA will provide vastly different amounts of electrical energy. Spokane’s semi-desert sun will trump perennially cloudy Seattle.

Tilt angle is very vital as well, as many residential roofs lack the proper angle to fully capture the sun’s rays from season to season. The angle should be approximately the same as the latitude of the site and must face no more than 15 degrees off from due south (in the Northern Hemisphere). If you wish to maximize summer performance angle the PV panels 15 degrees less than your latitude and for maximum winter generation tilt the panels 15 degrees more than your latitude.

Of course the best system is the one that tracks the sun throughout its journeys, and the pole mounted arrays do just that. These PV panels go via computer-controlled motors while different kinds of trackers go via the imbalance of fluid flowing through copper tubing heated by the sun. This motion of the panels acts to keep the surface exactly perpendicular to the sun at all times to maximize the sun’s energy that falls on them. Various forms of trackers can increase the production of energy by 25% or more over static systems.

What comes as a complete surprise to many residential solar energy neophytes is that the magnetic declination must also be taken into consideration. The difference between the magnetic poles of south and the right solar south has to be added or subtracted from your proper angle. While Minneapolis has a close to zero declination adjustment, Seattle’s is close to 19 degrees. Check one of the declination maps to find out how to adjust your array in your location.

The relative performance of PV panels varies widely, so it is best to read all of the manufacturer’s specification sheets as well as seek out independent reviews and evaluations. Although a truly effective residential solar power system can cost so much it may never be fully amortized in net electricity savings, home solar energy generation is certainly here to stay.

1. A Grid-Attached Home: This most common of residential solar systems allows for the solar energy to supplement your conventional electrical supply. Your home runs off a mixture of solar and grid energy at any given time. Should your solar system produce more electricity than is being used at the time, your electric meter will literally spin backwards as you are now feeding energy into the grid instead of drawing from it.

2. An Off-Grid Home: This residential solar system is set up to provide all of the home’s electric requirements as there are no conventional electric connections. The two major variants of this configuration are Autonomous & Hybrid. An Autonomous system derives all of the energy utilized by the home from the sun. A Hybrid system supplements the solar with a variety of sources such as wind or fuel fired generators. In many cases an off-grid home needs a fuel fired generator as a backup.

Both types of solar systems require a complex system to be installed on the residential building. PhotoVoltaic (PV) Solar panels are attached to the roof, then cables are run down to a series of batteries, inverters, and the electrical panel.

There are a wide variety of considerations concerning a home solar power system which must be addressed in the plotting stage. The solar panels must have an unshaded and unblocked southern exposure (in the Northern Hemisphere). If you are in a marginal location, high latitude (over 40 degrees), or a predominantly cloudy area you may want to take advantage of pole mounted arrays which can track the sun’s position to optimize power generation.

The expected electrical draw of the home must also be considered. Add up the electric needs of all the appliances and tools you wish to operate and the number of hours they will be used each day. Now you must estimate the PV array size by dividing the daily total electric load by the average number of hours of sunshine on your location. The relative efficiency of the solar power array will have a significant effect on these calculations, as will the number, size, capacity, and rating of the battery bank.

You will have to do your homework, as solar power systems vary widely from manufacturer to manufacturer, and even from model to model. The specification fact sheets will provide hard data on the relative efficiencies, and most solar power neophytes are astonished when they crunch the numbers of the equipment and the installation fees and realize that the final cost is well into five figures.

If you cannot afford the residential solar power system of your dreams, there are alternatives. Besides the obvious one of just saving energy conventionally, you can design a solar power system that is expandable and allows you to add battery capacity and PV panel square footage as you can afford them. Various locations also offer financial incentives for solar power installations. Some of these can be quite significant and can help make the choice for the solar power installation simpler.

Residential solar power is still in its infancy and the current barriers to entry are considerable, but prices are falling and efficiency is rising all the time, and you may relish the opportunity of being a solar pioneer in your neighborhood.