4. Maintenance
Occasional glass cleaning improves solar panel efficiency. Use a soft sponge and warm water
with a small amount of dishwashing detergent to gently clean the solar panel of any dust, grime,
or bird droppings. Use a soft, dry cloth or squeegee to remove any residual water from the panel.
If a problem with the solar panel is suspected, check the panel by measuring the voltage output.
Check the voltage with a voltmeter connected between the two wires from the solar panel. There
must be solar radiation incident on the panel and there must be a load connected to the solar
panel. The load can be a data logger, other equipment, or a 75 ohm resistor capable of
dissipating solar panel power between the two wires. No voltage output implies a bad solar
panel, or cable. The magnitude of the voltage output depends on the incident solar radiation.
5. Power considerations
5.1 Solar panel and storage batteries
The solar panel converts light energy to electricity, or specifically to direct current. The direct
current produced is used to provide power to the system and to charge storage batteries.
The solar panel operates in both direct and diffuse light (cloudy days), but not at night.
The minimum battery size and solar panel output required depend on:
l
The average current drain of the system
l
The maximum time the battery must supply power to the system without being charged
l
The location of the site
NOTE:
When some batteries are discharged below a specified voltage, the battery becomes
damaged and cannot be recharged.
On average, the solar panel must be able to provide at least the amount of power necessary to
operate the system for 24 hours. This means that the solar panel should not only be able to
supply power to the system during the day, but it should also be able to provide power necessary
to charge the battery for the power lost during the night. In addition, the battery must have
enough capacity to power the system during times of no charging (night) and several days of low
charging (cloudy and stormy days).
SP5, SP10, and SP20 Solar Panels
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