...
Due to the variance in the measuremntes, each mppt was taken out of the holders and tested with the bench supply and DC E-Load. The following table summarizes the results. Note that the input open circuit voltage was set to 27V by the output voltage setting potentiometer. The input open circuit voltage (voltage from power supply) should also always start at 20V (unless modified in the notes).
| MPPT# | DC E-Load Settings | V(in)oc | V(out)oc | Vin | Vout | Iin | Iout | max temp (deg C) | Notes | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 6ohm | 15.98 | 25.245 | 10.01 | 18.516 | 6.264 | 3.087 | 44 | 24-25V has audible frequency oscillations (can hear) | ||||||
| 1 | 7ohm | 15.98 | 25.245 | 33.01 | 32.339 | 4.608 | 4.62 | 31.3 | When in audible range, heat increases really quickly. With an increase in resistance on the E-load is a increase in the voltage output with a significant decrease in tehb the output current for a total less amount of output power . Maybe this has to be configured so the output voltage we want will get drawn, and the | 2 | 3 | 4 | 5 | 6 | (of course its following the inverse exponential curve until open circuit voltage in this case → infinite impedance). |
| 1 | 6ohm | - | - | - | 25.622 | 5.768 | 4.27 | 49 | during the time of this testing I also wanted to test the efficiency loss from running the mppt with an input voltage of 25-27V, in which the DCDC operates at an audible frequency of oscillations. Before the testing, I noticed that there was an increase in temperature at this frequency, so I wanted to find out the loss in efficiency. It was concluded that the loss in about 6 watts at this point, which was about the same power loss as at 20V input. It seems that the audible noise comes from the fact that the input voltage matches the upper limit of the output voltage determined by the output potentiometer. | ||||||
| 2 | 6ohm | - | - | - | 25.721 | 5.87 | 4.289 | 50 | preformed similarily to mppt #1 except that running it at 27V was 1W less efficient than under 27V. | ||||||
| 3 | 5ohm | - | - | - | 25.606 | 6.938 | 5.1206 | 43 | The power drop for this testing (as outlined) was 7W (about 1W more than normal) | ||||||
| 4 | 6ohm | - | - | - | 25.549 | 5.743 | 4.256 | 49 | About a 6.5W drop in efficiency. | ||||||
| 5 | 6ohm | - | - | - | 25.696 | 5.793 | 4.283 | 55 | Preforms similarly to the others, except gets to a higher temperature even though just 6W drop | ||||||
| 6 | 6ohm | - | - | - | 25.706 | 5.816 | 4.284 | 55 | Preforms similarly to the others, (6W drop) |
Note: I started testing in constant current mode to match the following diagram in terms of power out and in.
...
Each MPPT once unit tested, will be tested in series for the total array output power, and continuity. Like unit testing, this will be run for at least half an hour 10 minutes for full validation.
I will start by connecting 2 mppts in series, with an output voltage predicted to be about 50 volts with a current limited by the power supply/.
...
SPI Communication Testing of MPPTs
...