existing power supply is available on site, or more power than the standard models is required. In these applications
the solar panel, regulator and batteries are all external to the system, provided separately.
When determining the power budget, it is recommended to perform detailed calculations including the duty cycle
(on time / off time) for all subsystems and sensor power requirements, with safety factors to prevent deep battery
discharge, and to allow for solar panel loses over time. A spreadsheet power budget calculator with example values
for typical sensors, is available for download from:
Approximate Sunshine Duration Method
:
A significant factor in the power budget calculation is Sunshine Duration for the installation location. For initial
calculations, the map below can be used to categorize locations.
Zone
Recommended Ai1 model
Measurement frequency and online state
<1.0
Ai1-EXT (External power)
Maximum power conservation
1.0-1.9
Ai1-36W (4x9W+12Ah VR SLA)
May require communications window, and slow
measurement updates
2.0-2.9
Ai1-18W (2x9W+8Ah LiPo)
3.0-3.9
Ample power, full-time online, high frequency
measurements
4.0-4.9
5.0-5.9
6.0+
Detailed Method
:
Sunshine Duration is not the same as Equivalent Sunshine Hours which the spreadsheet uses. For detailed
calculations, it is recommended to use the Apogee “Clear Sky Calculator” available from the Google Play store:
https://play.google.com/store/apps/details?id=com.apogee.clearsky
This app can be used to calculate the ESH for the worst day of the year (typically the winter solstice: 21
st
December
in the Northern hemisphere, 21
st
June in the Southern hemisphere). If an Android phone is not available, a
can be used although the setup data is more difficult. Select the size by Zipcode, by Map, or by entering the
latitude and longitude, and configure the winter solstice day. The app will return the solar output at that time of
day. Use a spreadsheet to record the output for each hour of the day and divide the total by 1,000 to calculate ESH.
