DIY Manual

7 | P a g e 10-543-1 REV A
DIY Manual
1. Assume our 250W panel has a Voc of 37V
2. If we round-down and wire 3 panels in series, we get an input voltage of 111V (37V x 3).
3. If we round-up and wire 4 panels in series, the input Voc will be 148V (37V x 4).
What is the input voltage limit of your charge controller?
If the input limit is 150V, which is common, then you can safely wire up 3 panels in series. But
remember, 3 panels are less than your load analysis calls for!
If the input limit is 150V and you wire up 4 panels, the 148V input is so close to the 150V limit,
that with cold temps slightly below 25
o
C/77
o
F your controller will stop working until the ambient
temperature rises enough that the PV array’s Voc drops below 150V.
In this example, you are best served by wiring 2 panels in series, the other 2 panels in series, then
combine both strings in parallel. OR … use the Classic 200 which allows for a 200Voc input.
However, for a 48V system, we now have a new problem! This 2-panel-in-series configuration
gives you an input voltage of 74V (37V x 2 panels in series), which is not high enough to fully
charge a 48V bank. Remember, Voc needs to be at least 133% of the highest charge voltage. In
a 48V system, the EQ voltage may be 61V. So 61V x 133% = 81V. The 2 panels in series is not
quite enough at 74V.
Cold Temperatures Corrections
Electrons like cold temps! They flow easier. As such, cold temps
will raise the Voc of your panels. So be mindful of the series-
string Voc of your panels into the charge controller when
operating in cold temps. For example, say your series string has
a Voc of 141V and the charge controller has a 150V input limit.
This leaves little room for colder temps. If the Voc exceeds 150V,
both the Classic and the KID charge controllers will go into a self-
protection resting mode called HyperVOC. This mode offers
protection against an over-voltage condition based on Classic
model and battery bank voltage (for the KID, HyperVoc occurs
from 150V to 162V). The Classic 150 in 24V offers HyperVoc to
174V (150 + 24).
The Brat has no buffer, so do not exceed 60V on the input.
Let’s assume your series string into the CL150 is wired at 135Voc and your locale can
experience cold temps down to -20C. Multiple 135V by the correction factor of 1.18 = 159.3V.
In this example, the Classic will go into HyperVOC until the Voc drops below 150V.
Correction Factors for
Ambient Temperatures
Ambient Temp Factor
14 to 10 C 1.06
-1 to -5 C 1.12
-16 to -20 C 1.18