Most simple series connected solar panels are rated into three categories :
* 15 to 16 volts - 30 to 32 cells per panel
* 16.5 to 17 volts - 33 to 34 cells per panel
* 17.5 to 21 volts - 35 to 36 cells per panel
15 to 16 volt panels are referred to as self-regulating panels because they do not produce enough voltage to overcharge batteries, which results in gassing. For this reason they do not require a charge regulator as the other panels do. This reduces the cost and maintenance of a system. These are referred to as battery maintainers, and are excellent to use in small system with one battery if the system does not have much of a power drain. Electric fences, and other low power applications that have limited energy use can use these types of solar panels.
16.5 to 17 volt panels are adequate for full fledged power systems in locations that generally get a lot of sun year round.
The preferred panel for most solar charging applications is a 35 to 36 cell panel which delivers from 17.5 to 21 volts open circuit voltage. A 36 cell panel is recommended for very hot climates in order to offset power output loss from high temperature. They also compensate for voltage drop in systems with long wire runs.
Designer watts
Designer wattage is simply the open circuit voltage multiplied by the short circuit current. Panel designers use this figure to rate the components used in the panel and peripheral components.
If a panel delivers about 20 volts open circuit and 3.5 amps short circuit current, the designer wattage would be 70 watts. The system components must be able to handle 70 watts, at 3.5 amps and 20 volts.
A panel rated at 70 designer watts will probably give you about 54 watts in real use and it will vary depending on the efficiencies of the cells as well as other conditions.
More about Green Energy and Solar Panels can be found at http://solar-panels-info.blogspot.com.
* 15 to 16 volts - 30 to 32 cells per panel
* 16.5 to 17 volts - 33 to 34 cells per panel
* 17.5 to 21 volts - 35 to 36 cells per panel
15 to 16 volt panels are referred to as self-regulating panels because they do not produce enough voltage to overcharge batteries, which results in gassing. For this reason they do not require a charge regulator as the other panels do. This reduces the cost and maintenance of a system. These are referred to as battery maintainers, and are excellent to use in small system with one battery if the system does not have much of a power drain. Electric fences, and other low power applications that have limited energy use can use these types of solar panels.
16.5 to 17 volt panels are adequate for full fledged power systems in locations that generally get a lot of sun year round.
The preferred panel for most solar charging applications is a 35 to 36 cell panel which delivers from 17.5 to 21 volts open circuit voltage. A 36 cell panel is recommended for very hot climates in order to offset power output loss from high temperature. They also compensate for voltage drop in systems with long wire runs.
Designer watts
Designer wattage is simply the open circuit voltage multiplied by the short circuit current. Panel designers use this figure to rate the components used in the panel and peripheral components.
If a panel delivers about 20 volts open circuit and 3.5 amps short circuit current, the designer wattage would be 70 watts. The system components must be able to handle 70 watts, at 3.5 amps and 20 volts.
A panel rated at 70 designer watts will probably give you about 54 watts in real use and it will vary depending on the efficiencies of the cells as well as other conditions.
More about Green Energy and Solar Panels can be found at http://solar-panels-info.blogspot.com.
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