The Basics
Solar panels are directed at solar south in the northern hemisphere at an angle dictated by the geographic location and latitude of where they are to be installed. Typically, the angle of the solar array is set within a range of between site-latitude-plus 15 degrees and site-latitude-minus 15 degrees, depending on whether a slight winter or summer bias is desirable in the system. Many solar arrays are placed at an angle equal to the site latitude with no bias for seasonal periods.
The electrical charge generated by the panels is consolidated in the PV panel and directed to the output terminals to produce low voltage (Direct Current) - usually 6 to 24 volts. The most common output is intended for nominal 12 volts, with an effective output usually up to 17 volts. A 12 volt nominal output is the reference voltage, but the operating voltage can be 17 volts or higher much like your car alternator charges your 12 volt battery at well over 12 volts. So there's a difference between the reference voltage and the actual operating voltage.
The intensity of the Sun's radiation changes with the hour of the day, time of the year and weather conditions. To be able to make calculations in planning a system, the total amount of solar radiation energy is expressed in hours of full sunlight per m², or Peak Sun Hours. This term, Peak Sun Hours, represents the average amount of sun available per day throughout the year.
It is presumed that at "peak sun", 1000 W/m² of energy reaches the surface of the earth. One hour of full sun provides 1000 Wh per m² = 1 kWh/m² - representing the solar power received on a cloudless summer day on a surface directed towards the sun.
The daily average of Peak Sun Hours, based on either full year statistics, or average worst month of the year statistics, for example, is used for calculation purposes in the design of the system. To see the average Peak Sun Hours for your area in the United States, you can click the following link which will open a new window - just close it [X] when you're done to return here; U.S.-Solar Insolation Choose the area closest to your location for a good indication of your average Peak Sun Hours.
Battery Systems
Battery systems utilize the same solar panels as an inter-tie system, but use a different (battery-capable) inverter and a battery system to store that power until you need it. This allows you to provide power when the sun is down, or in the case of those who are attached to the utility grid, to retain power even if the local power grid goes out. This is especially valuable for residences and facilities with medical, computer or other specialized and sophisticated equipment which not only must be protected from fluctuating power availability, but require the "cleanest" power available.
 |
There are a variety of manufacturers out there who specialize in making battery systems. These manufacturers, including Xantrex and Outback, typically provide these components on a common "power panel" framework which not only allows for a cleaner appearance, but can come pre-wired from the factory for a fast, easy and factory-warrantied installation.
Intertie Systems
Inter-tie systems, sometimes called grid-tie or non-battery systems, are the simplest way to generate grid-quality power (or better) to your home. The system includes a number of solar panels and a sinewave inverter, which connects to your power supply and feeds power back through your utility meter into the grid.
These systems tend to be less expensive than battery systems. Additionally, they tend to stabilize the local power grid in their immediate area. During the day, your electrical meter runs backwards instead of forwards, resuming normal operation when the sun goes down. Since the majority of homeowners pay more for their power above their baseline amount, the simple way to understand this is that solar power pays for your most expensive power first!
 |
