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29-06-2023: Preliminary MPPT Testing
The DC Load used in these experiment was Rigol DL3031 DC Electronic Load
Tested one of the MPPT boards using a power supply (Sparky) and load (Rigol DL3031)
Load set to 25V, power supply to 2A and set to ~8V (max 15V)
Power output around 16W, an efficiency of ~91-92%
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23 degrees, pretty decent sun (see picture)
Using Stack 9 (7 cells * 4 cells) (with a bit of clouds Apple Maps that day said it was “Partly Cloudy”)
With the protective film Voc = 18.5V, Isc = 0.92 A, P = 17.02W
Without protective film, Voc = 18.7V and Isc = 1.22 A, P = 22.814 W
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Sun was out and bright again. The film was left on
Battery pack: V = 25V, I = 2A, P = 50W
No record of solar panel output
At a similar light intensity, the film was removed
Battery pack: V = 25V, I = 2.4 A, P = 60W
We noticed that if you shade even one cell, it the current going through the batteries dropped form 2A to 1.6A
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Stack 7 (7*4), film on, very bright day: Voc = 18.6V, Isc = 4.7 A, P = 87.42W
Setup: Stack 7 and stack 9 (each 7 cells * 4 cells) forming a combined 56 cells. Two MPPT’s were used - one MPPT for each stack. Let MPPT_9 be the MPPT connected to be continued)Stack 9 and MPPT_7 be the MPPT connected to stack 7. We connected the output negative terminal of MPPT_9 to the negative terminal of the DC Load, the output positive terminal of MPPT_9 to the output negative terminal of MPPT_7, and the output positive terminal of MPPT_7 to the positive terminal of the DC Load. Initially, we were getting a high frequency noise from the MPPT’s. This was because we forgot to replace the capacitor. When connecting to the DC Load, always place a capacitor across the MPPT output
Under sunny conditions, with the film on both the stacks:
DC Load: V = 50V, I = 1.898 A, P = 94.985
Setup: Same as above. Instead of connecting to a DC Load, we connected to the battery
Slightly cloudly
Battery pack: V = 50V, I = 0.7A, P = 40W
Sun brighter
Battery pack: V = 50V, I = 2A, P = 100W