Portable Power Module for Güralp Certimus
Operation
4.2.2.2 Wind considerations
Solar panels exposed to winds cause vortices and eddies downwind of the panel.
These can couple to the ground, creating earth movements which can be detected by
seismometers. For this reason, the solar panel(s) should be installed a suitable
distance away from the instrument's emplacement.
4.2.2.3 Temperature considerations
The PPM must be protected from extreme temperatures during operation. If the
ambient temperature falls below 0° C or rises above 45° C, charging of the lithium-ion
cells inside the PPM will be adversely affected.
If the chosen installation site may get too cold, thermal insulation around the PPM
may maintain its temperature by trapping its own operational heat energy. If the site
may get too hot, burial of the PPM may be required to protect the PPM from direct
sunlight.
For more information, please refer to section 6.1.2 on page 20.
4.2.2.4 Incident light
To maximise the chance of harvesting energy, the panel should be aligned so that
the surface is perpendicular to the incident sunlight. As the sun traverses across the
sky during the day, however, the instantaneous optimum alignment will change. A
compromise alignment needs to be chosen to maximise the total energy captured
across the deployment duration. There are many on-line ‘Solar Panel orientation
calculators’ available which can provide information regarding the best orientation
of the panel, given the location and season.
When deploying in winter, note that the amount of foliage on surrounding plants and
trees can increase dramatically in the spring and summer. Take care not to choose a
location which could end up being in shadow.
4.2.3 Principle of operation
4.2.3.1 Charge curves
Solar panels provide energy at different rates during daylight periods, depending on
the intensity and angle of the incident light, and not at all during darkness. The total
energy provided by the solar panels, summed over a day, must be higher than that
required by the Certimus and any ancillary equipment, also summed over a day. If
the length of a day is likely to vary over the lifetime of the deployment, this must
also be taken into consideration. For this reason, the nominal power - expressed in
Watts - of the required solar panel(s) will be considerably higher than the average
power draw of the connected equipment.
In the graph below, the incoming power from the solar panel(s) is shown as the red
curve and the outgoing power for the instrumentation and ancillaries is shown by
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Issue A - May 2021
