Solar Power
Solar panels work by converting sunlight into electrical energy.
A typical solar panel comprises of 32 to 36 elements electrically connected in series thereby producing a panel with an open circuit voltage of 18 to 22 Volts.
The silicon material used in the panel comes in three basic forms, monocrystalline silicon, polycrystalline silicone and amorphous silicon.
Monocrystalline
Monocrystalline silicone is grown as one large crystal and subsequently cut into thin slices to form the individual cells. Panels made this way are a little more efficient, around 14-16%, but are also more expensive to produce. These panels usually comprise 34 to 36 elements producing 20 to 22 Volts open circuit.
Polycrystalline
Polycrystalline silicon is cast in blocks and the final cut slices consists of many smaller crystals. Manufacturing costs are lower, therefore these panels are little cheaper to purchase. While the efficiency is a little lower, around 12-14%, the low angle light output can be higher, but they generally do not perform quite as well as monocrystalline types at higher panel temperatures.
Amorphous
Amorphous silicon panels are produced by a completely different and cheaper process by depositing vaporised silicon directly on to a backing material. This results in a cheaper panel but the efficiency is half that of mono or polycrystalline types, around 6%. This means you need twice the panel surface area to achieve the same output. They do have one advantage however; the amorphous silicon can be applied to a flexible backing such as plastic or thin stainless steel to result in a flexible panel with the ability to be laid on a curved surface. However, these flexible panels usually have a poor Watt to Dollar ratio.
Solar panels are available in a variety of sizes. The larger the panel size or area, the greater the electrical output. Common sizes range from 5 Watt to 185 Watt. The maximum output will only be achieved when the panel is pointing directly at the sun and the panel temperature is 25 deg C or less. Since our panel will be mounted horizontally, we will never quite see the full output as shown in the table below.
| Angle of Sun to Panel | % of Rated Output (Approximate only) |
| 90 Deg | 100% |
| 75 Deg | 95% |
| 45 Deg | 75% |
| 30 Deg | 50% |
As you can see from the table, the output will vary depending on your latitude as well as the time of day. For example, if you are in Cairns (latitude of 17 Deg S) your panel output at noon will be 90-95% of the panel's maximum, if you are in Hobart (latitude of 43 Deg S) your panel's output at noon will be around 75% of maximum. These figures are approximate only and depend on the type of panel.
Also remember that during the winter months the sun is much lower in the sky (greater angle to the panel) and the days are much shorter resulting in approximately half as many Amp Hours collected per day.