Electronics > Power/Renewable Energy/EV's
Troubleshooting Lost Watts
OpenCircuit:
I have 4-100 Watt panels in parallel hooked to a 40amp MPPT controller that is charging 4 golf cart batteries in a 12v system. During an independent test each panel was producing 90watts, but when all panels are tied together via a 4-to-1 parallel connector wattage does not exceed 201watts from the panels according to the charge controller when no load is applied to the system. However when a 200 watt load on the system the controller reports 283 watts.
The 4-to-1 connector is connected to 50ft cables running to the controller.
Is the charge controller bucking the excess energy being produced by the panels? The controller is indicating MPPT charge mode, not boost or float, so the batteries are not fully charged... Confused? Appreciate any suggestions.
fourtytwo42:
It would be nice to help someone instead of the usual drivel in the renewables section :)
My first option would be your charge controller has a current limit lower than the output of your 4 panels, perhaps you could provide a link or spec for the controller ?
Second is that your 4 panels are not matched (same make/type/age etc) or are not evenly illuminated (same direction/tilt/shade) either of these could cause some of the panels in a parallel array to partially shunt the others UNLESS your "parallel connector" incorporates diodes ?
50ft is a long way at just 12V, you may also be suffering excessive voltage drop on those cables! especially if you are using cables designed for 10 Amps to carry 40 Amps ? This may be interfering with the controllers MPPT algorithm.
Just a few things to think about :)
jmelson:
It seems like it might be a much better scheme to put the panels in series. I think there are a lot of problems when paralleling panels.
Jon
OpenCircuit:
Thanks for the replies. Here is a link to the CC: https://www.renogy.com/rover-li-40-amp-mppt-solar-charge-controller/
All panels are matching.
Yeah, I was thinking the voltage drop might be a result of the 50' panel wires, but the panel wattage increases significantly when I put a load on the system.
I was thinking possibly I am using too small of a wire (16AWG) from the batter terminals to the CC, but again solar panels wattage increases to nearly 300 when the system is loaded. This wire is around 10' long.
Panel Specs:
Specifications
Maximum Power 100W Solar Cell Type Polycrystalline
Optimum Operating Voltage (Vmp) 18.2V Connection MC4
Optimum Operating Current (Imp) 5.49A Quantity 1
Maximum System Voltage 1000 V(IEC) Length 40.00
Open-Circuit Voltage (Voc) 22.8V Width 27.00
Short-Circuit Current (Isc) 5.95A Height 1.40
ahbushnell:
--- Quote from: OpenCircuit on March 27, 2019, 08:27:38 pm ---Thanks for the replies. Here is a link to the CC: https://www.renogy.com/rover-li-40-amp-mppt-solar-charge-controller/
All panels are matching.
Yeah, I was thinking the voltage drop might be a result of the 50' panel wires, but the panel wattage increases significantly when I put a load on the system.
I was thinking possibly I am using too small of a wire (16AWG) from the batter terminals to the CC, but again solar panels wattage increases to nearly 300 when the system is loaded. This wire is around 10' long.
Panel Specs:
Specifications
Maximum Power 100W Solar Cell Type Polycrystalline
Optimum Operating Voltage (Vmp) 18.2V Connection MC4
Optimum Operating Current (Imp) 5.49A Quantity 1
Maximum System Voltage 1000 V(IEC) Length 40.00
Open-Circuit Voltage (Voc) 22.8V Width 27.00
Short-Circuit Current (Isc) 5.95A Height 1.40
--- End quote ---
50 ft of wire times two with 4X5.95A is 48 watts.
If the light on the panels is not all the same then that will impact the efficiency.
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