• solar panel basics

    Solar panel arrays - Renewable Ventures Solar PlantSolar Panel outputThe output of a solar panel is usually stated in watts, which is determined by multiplying the rated voltage by the rated amperage. The formula for wattage is VOLTS times AMPS equals WATTS. For example, a 12 volt 60 watt solar panel measuring about 20 X 44 inches has a rated voltage of 17.1 and a rated 3.5 amperage.

    V x A = W
    17.1 volts times 3.5 amps equals 60 watts

    Since sunlight intensity varies throughout the day, we use the term “peak sun hours” as to smooth out these variations into a daily average. Early morning and late-in-the-day sunlight produces less power than does the mid-day sun. Naturally, cloud cover also affects power production. Each geographical region has an Average Peak Sun Hours per Day rating which compensates for regional weather conditions and latitude.

    If an average of 6 hours of peak sun per day is available in an area, then a 60 watt solar panel produces an average 360 watt hours of power per day:

    60w times 6 hrs. = 360 watt-hours.

    Solar panels are wired in series or parallel to increase voltage or amperage respectively. They can be wired in both series and parallel to increase both volts and amps.

    Series wiring-Series wiring refers to connecting the positive terminal of one panel to the negative terminal of another. The resulting voltage across the across the terminals of the combined solar panels is the sum of the voltage of the two individual panels, but the current remains constant for both solar panels. For example, two 12volt/3.5 amp solar panels wired in series produce 24 volts at 3.5 amps. Four series wired solar panels produce 48 volts at 3.5 amps.

    Parallel wiring-Parallel wiring refers to connecting positive terminals to positive terminals and negative to negative. The resulting voltage stays the same, but amperage becomes the sum of the number of solar panels. Two 12 volt/3.5 amp solar panels wired in parallel produce 12 volts at 7 amps. Four solar panels would produce 12 volts at 14 amps.

    Series/parallel-Series/parallel wiring refers to combining both of the above – increasing volts and amps to achieve the desired system voltage as in 24 or 48 volt systems and desired amperage. The following diagram reflects this. In addition, the four panels below can then be wired in parallel to another four and so on to make a larger solar array. Most grid tie solar panels are series wired to increase voltage which makes wire size smaller and decreases the amount of wire in such systems.