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Fix mpp temperature sensitivity #68

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Merged
merged 6 commits into from
Mar 21, 2018
Merged

Fix mpp temperature sensitivity #68

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f62cc7e
Merging v4 branch before submitting PR (#1)
rayhickey Feb 26, 2018
f4491a4
Merge branch 'master' of https://github.com/rayhickey/PVMismatch
rayhickey Feb 26, 2018
df4e90c
Fixes MPP Sensitivity to Temperature
rayhickey Feb 26, 2018
3bcdf20
Correct indices
rayhickey Feb 26, 2018
b25ea18
Cleanup
rayhickey Feb 26, 2018
990ce8b
Changed setsuns test for new MPP calculation
rayhickey Mar 19, 2018
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18 changes: 15 additions & 3 deletions pvmismatch/pvmismatch_lib/pvsystem.py
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Original file line number Diff line number Diff line change
Expand Up @@ -94,9 +94,21 @@ def calcSystem(self):

def calcMPP_IscVocFFeff(self):
mpp = np.argmax(self.Psys)
Pmp = self.Psys[mpp]
Vmp = self.Vsys[mpp]
Imp = self.Isys[mpp]
P = self.Psys[mpp - 1:mpp + 2]
V = self.Vsys[mpp - 1:mpp + 2]
I = self.Isys[mpp - 1:mpp + 2]
# calculate derivative dP/dV using central difference
dP = np.diff(P, axis=0) # size is (2, 1)
dV = np.diff(V, axis=0) # size is (2, 1)
Pv = dP / dV # size is (2, 1)
# dP/dV is central difference at midpoints,
Vmid = (V[1:] + V[:-1]) / 2.0 # size is (2, 1)
Imid = (I[1:] + I[:-1]) / 2.0 # size is (2, 1)
# interpolate to find Vmp
Vmp = (-Pv[0] * np.diff(Vmid, axis=0) / np.diff(Pv, axis=0) + Vmid[0]).item()
Imp = (-Pv[0] * np.diff(Imid, axis=0) / np.diff(Pv, axis=0) + Imid[0]).item()
# calculate max power at Pv = 0
Pmp = Imp * Vmp
# calculate Voc, current must be increasing so flipup()
Voc = np.interp(np.float64(0), np.flipud(self.Isys),
np.flipud(self.Vsys))
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15 changes: 9 additions & 6 deletions pvmismatch/tests/test_setsuns.py
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Original file line number Diff line number Diff line change
Expand Up @@ -16,42 +16,45 @@
def test_basic():
pvsys = PVsystem()
pvsys.setSuns(.75)
ok_(np.isclose(pvsys.Pmp, 23907.936630685774))
ok_(np.isclose(pvsys.Pmp, 23903.15106763))


def test_dictionary():
pvsys = PVsystem()
Ee = {1: {3: {'cells': np.arange(30), 'Ee': [.25] * 30}}}
pvsys.setSuns(Ee)
ok_(np.isclose(pvsys.Pmp, 31618.1813179655))
ok_(np.isclose(pvsys.Pmp, 31610.21081155355))


def test_set_mod_1():
pvsys = PVsystem()
Ee = {1: {3: [.2], 0: [.1]}}
pvsys.setSuns(Ee)
ok_(np.isclose(pvsys.Pmp, 29566.303088387336))
ok_(np.isclose(pvsys.Pmp, 29559.422265401034))


def test_set_mod_2():
pvsys = PVsystem()
Ee = {1: {3: .2, 0: .1}}
pvsys.setSuns(Ee)
ok_(np.isclose(pvsys.Pmp, 29566.303088387336))
ok_(np.isclose(pvsys.Pmp, 29559.422265401034))
# 1001 points linear: [ 29579.12191565]


def test_set_str_1():
pvsys = PVsystem()
Ee = {1: [.1]}
pvsys.setSuns(Ee)
ok_(np.isclose(pvsys.Pmp, 29136.544447716446))
ok_(np.isclose(pvsys.Pmp, 29133.81083801798))
# 1001 points linear: [ 29141.73034719]


def test_set_str_2():
pvsys = PVsystem()
Ee = {1: .1}
pvsys.setSuns(Ee)
ok_(np.isclose(pvsys.Pmp, 29136.544447716446))
ok_(np.isclose(pvsys.Pmp, 29133.81083801798))
# 1001 points linear: [ 29141.73034719]


def test_gh34_35():
Expand Down