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SunPower / PVMismatch

An explicit Python PV system IV & PV curve trace calculator which can also calculate mismatch.
http://sunpower.github.io/PVMismatch/
BSD 3-Clause "New" or "Revised" License
79 stars 30 forks source link

Diode behavior in PVstring #1

Closed bmeyers closed 11 years ago

bmeyers commented 11 years ago

PVstring model doesn't allow for a module's diodes to be completely activated. See email sent to Mark M. on 4/28/13.

mikofski commented 11 years ago

traced the bug to the "trial" current points Imod in PVmodule.calcMod() in pvmismatch.pvmodule. Because all of the cells' Ee was set to 0.1, the max irradiance was 0.1 and the max trial current was 0.1*Isc0 = 0.6[A], but the reverse bias part of the cells' I-V curves had current > 0.6[A] so the bypass diodes were never turned on.

Suggested solutions:

  1. Changing one cell to have Ee = 1 sun fixes the problem - but it's desired to model the OP's case.
  2. Better solution - suggested by OP - is to make "trial currents" static, ie always range up to 1 sun * Isc0.
  3. Another option is to check the cell values themselves - and limit max current range to that range.