MidNite Solar Kid Manual

The KID Solar Charge Controller Instructions
HyperVOC
Why do you need HyperVOC?
PV panels can put out full voltage even in very low light conditions, such as first light just before
dawn. These low light levels do not have enough intensity to produce current flow, so the controller is
not producing power at this point. This voltage is known as Open Circuit Voltage or Voc. Colder
ambient temperatures cause solar panels to have higher open circuit voltages. Depending on the
array configuration, that voltage may exceed the maximum operating voltage limit of the controller.
Hyper VOC is a non-operational buffer between The KID Charge Controller's maximum operating
PV input voltage of 1 51 and the absolute maximum of 1 62.
When the array's input voltage is between 1 51 V and 1 62V, The KID is unable to charge the battery
bank, but it has not been harmed by over voltage. Any voltage above 1 62V will result in severe damage
to the charge controller which is not covered by warranty. Hyper VOC, coupled with a properly designed
array, will protect your charge controller from being over voltaged during unusually cold weather.
For example, consider a system configured with 4 modules in series and each panel has an open
circuit voltage (VOC) of 36.9V. This system is located in Alberta, Canada and the lowest outside
ambient temperature that they see during the coldest months of the year is -32°C.
First, we figure the array voltage: 4 panels in series is 4 x 36.9V, giving us an array voltage of 1 47.6V. At first
glance, this array voltage looks OK but what happens when the temperature drops. We know the lowest
outside ambient temperature is -32C and the module reference temperature is 25C. So -32C is 57 degrees
colder than the reference temperature. This module manufacturer has a temperature coefficient of .33%. This
means that for every degree below 25C, the voltage increases by about 1 /3 of 1 %. 57 degrees X 0.33% = 1
8.81 %. 1 47.6 volts X 11 8.8% = 1 75.4 volts. This voltage will destroy the charge controller.
In this example 3 panels in series would be the better choice. And rather than do this longhand for each calculation,
please use Midnite's KID String Sizing Tool at http://www.midnitesolar.com/sizingTool_kid/index.php.
Above: HyperVOC voltage limits above normal
operating voltage.
Right: Solar Panel VOC adjustments by temperature.
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