# Electrical Efficiency Regarding PV Panels

Solar Expert Posts: 364 ✭✭
Since I will be receiving a new MPPT controller soon (The Kid), I figured I would go and check out the Kid Sizing Tool to look at different figures.

Observation: While changing the parameters (number of panels in series versus strings, and system voltages), I began wondering which way would be best to wire the array.

Please keep in mind, this has nothing to do with my current loads. This will be a completely separate system from my existing array. (vtmaps was the one whom I got this idea from, in a post he made in one of my threads.) Also, this is completely hypothetical at this point.

Goal: What I am trying to learn here is, which, given the option, is the most efficient way to wire panels with this particular controller (The Kid), to my off-grid array.

Panels in Series: 2, Strings: 4, Batteries: 24 volts

Rated PV Array Power:
800
Watts

Anticipated Array Power @ 33C:
770
Watts

Rated PV Array Current:
22.16
Amps

Battery Charging Current @ 28.8 V:
27.8
Amps

VMP (Maximum Power Point Voltage) :
36.1
Volts

VOC (Open Circuit Voltage):
44.88
Volts

VMP @ 18 C°:
37.2
Volts

VOC @ 18 C°:
46
Volts

Panels in Series: 4, Strings: 2, Batteries: 24 volts

Rated PV Array Power:
800
Watts

Anticipated Array Power @ 33C:
770
Watts

Rated PV Array Current:
11.08
Amps

Battery Charging Current @ 28.8 V:
27.8
Amps

VMP (Maximum Power Point Voltage) :
72.2
Volts

VOC (Open Circuit Voltage):
89.76
Volts

VMP @ 18 C°:
74.4
Volts

VOC @ 18 C°:
92
Volts

Panels in Series: 1, Strings: 4, Batteries: 12 volts

Rated PV Array Power:
400
Watts

Anticipated Array Power @ 33C:
385
Watts

Rated PV Array Current:
22.16
Amps

Battery Charging Current @ 14.4 V:
27.8
Amps

VMP (Maximum Power Point Voltage) :
18.05
Volts

VOC (Open Circuit Voltage):
22.44
Volts

VMP @ 18 C°:
18.6
Volts

VOC @ 18 C°:
23
Volts

Panels in Series: 4, Strings: 1, Batteries: 12 volts

Rated PV Array Power:
400
Watts

Anticipated Array Power @ 33C:
385
Watts

Rated PV Array Current:
5.54
Amps

Battery Charging Current @ 14.4 V:
27.8
Amps

VMP (Maximum Power Point Voltage) :
72.2
Volts

VOC (Open Circuit Voltage):
89.76
Volts

VMP @ 18 C°:
74.4
Volts

VOC @ 18 C°:
92
Volts

Please keep in mind one constant. That is, the distance for the wires from any array to its respective controller, will not be farther than 6.0 meters, one-way. The respective battery banks will be within 1.5 meters, one-way, of the controllers.

So, would someone, please, give me your input on each of these results, and which (of each system) are wired most efficiently? Or, does it really matter, since the charging current is the same in both scenarios, and in both voltages?

I want to learn as much as I can. This forum, by far, has been the best way to do that since I began this journey.
Paul

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Re: Electrical Efficiency Regarding PV Panels