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The first part of the process involved combining both mppts in series, and based on the resources in the bay, testing was limited to the 1A output from one of the power supplies. Both mppts were set for a V(out)oc of about 27V, and limited to a current out of 1A. The dc load was set to constant resistance mode, and decreased from 100ohms until the resistance before either power supply would go into constant current mode. Both power supplies were set to 20V input.
The following table outlines the results:
| Current input MPPT1 | Current Input MPPT2 | DC Load Voltage | DC Load Current | DC Load Resistance | Max Temperature | Notes |
|---|---|---|---|---|---|---|
| 0.906 | 0.985 | 50.543 | 0.7218 | 70 | negligible | When the resistance is decreased so that one of the mppts goes into constant current mode, the mppt cannot stabilize itself at a specific voltage, and instead fluctuates like crazy. This may be an issue if a mppt needs to maintain a certain current output, and one mppt lags behind others. Also in any case, one (or both) of the mppts will have fluctuating current (before current limit is met) in order to keep a constant current from the constant resistance. |
| 2.819 | 2.595 | 49.907 | 2.0787 | 24 | 32.5 | was using two power supplies limited to 3A output (still decreased CR value until one of them went into constant current mode) 20V input for this and above on power supplies |
| 2.818 | 2.605 | 57.759 | 2.595 | 20 | 30 | Input on mppt 1 is 25V and on 2 is 32V (limits of the power supplies) |
Array testing
This test will determine the power out of the arrays at 12pm on a cloudy day (to be repeated on a sunny day) the test will simply put each section of the array in constant resistance mode, and measure the output voltage and current (essentially the power). The eload will be set to 1kohm in constant resistance mode then again at 10ohms.
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SPI Communication Testing of MPPTs
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