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Date: 2023-09-22

Objective: Connect all 12 10 MPPTs (6 5 in series, in parallel x2), then connect to the a full battery back, read current on a sunny day

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TODO LIST:, hopefully the battery charges

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Testing Results:

Conditions/Setup:

6:30pm, sun was still above trees but starting to set, hitting solar panels through the windows at around 40 degrees from the horizon
Panels were laid flat across the table with a transparent plastic layer on top
10 panel packs were laid out, with the left and right chain being mirrors of each other (same # and type of panels)
Left and right voltage were both set to 157V when no load was connected
MPPTs were chained with crimped wires, panels connected to MPPTs with aligator clips
Schematic was same as shown above, but with an ammeter in series with the fuse/battery

Results:

With both MPPTs series outputs set at 157V, and battery pack at 117.2V, there was 28mA of current being drawn (3.2W)
The battery voltage was increasing at a rate of roughly 10mV/2seconds (starting at 117.6V)

Findings:

10 MPPTs worked: 8 of them were 18-33V, 2 of them were 23-37V
3 MPPTs were not used: 1 was confirmed damaged from before (said ‘shorted’ on the bottom), the other two did not work (low input and output voltages) when we plugged them in
After battery was connected, voltage before and after both diodes were 117V (VBAT)

Next Steps

Conduct test outside, where none of the panels are under shade
Map which arrays go to which MPPT, then tune the MPPT outputs to be proportional to #cells
- ideally this is same as what we use on car!
Check Isc on all panels
Use 2 ammeters: 1 for each line
- Does each line contribute relatively equal amounts of current?
Use Ideal diodes?
Use 2 voltmeters: 1 for each line

(OLD TO-DO LIST)

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