Now is a good time to invest in a solar power (PV) system. The cost of solar panels, the component you see on roofs and the single most expensive component, is down from 2008. Utility and tax incentives reduce the net cost of a PV system to an amount that is manageable for many people. Cost recovery can take as little as six to eight years. After that, all the power from your system is effectively cost free.
The following are the most important aspects that you should consider when designing your PV system.
- Array orientation The solar panel array should face as close to due south (180 degrees) as possible. An array that is off azimuth (facing other than south) provides less power. One traditional PV system panel needs about 16 square feet of roof area for every 200 watts of power. For example, a 4,000 watt PV system needs about 320 square feet of south-facing roof area.
- Array tilt angle An ideal array will have the sun at a 180 degree angle to the array for as much of the day as possible. The ideal roof pitch where the array will be mounted depends on your local latitude. A higher latitude means a higher pitch roof is required to create the ideal tilt angle. Few PV systems have an ideal tilt angle. An array with a more oblique tilt angle provides less power, but it may not be worth spending too much additional money just to create the ideal tilt angle.
- Shade Trees, buildings, chimneys, and other things that cast a shadow on the array at any time during the day reduce PV system power output. Locate the solar panel array to avoid shade.
- Roof covering condition PV system panels may last twenty-five years or more. This is longer than the design life of most roof covering materials. Ideally, you should install the panels over a roof covering that will last as long as the panels. Otherwise you may have to remove the panels when installing a new roof covering.
- Component location Electric utilities usually require ready access to the AC disconnect switch so that its personnel can assure themselves that the PV system is disconnected while they work on their equipment. This often means locating the AC disconnect switch near the meter or at some other point that is not behind doors or gates that may be locked. The inverter and the DC disconnect switch can, in theory, be located in any accessible location. If located outdoors, the inverter should be in the shade and protected from the elements to the extent possible.
- Electrical panel condition Solar systems usually require two circuit breaker slots in the electrical panel to connect the PV system power to home’s electrical system. If your electrical panel has no more circuit breaker slots or if it is an old panel containing fuses, changes at the panel or a full panel upgrade may be required.
Solar energy systems can work in almost any environment, when properly designed and installed. Doing your part to help your country achieve energy independence and to help the environment feels good. Significantly reduced electricity bills also feels good.