A silicon module is rated at standard test conditions ( , ): , ,

PHYSICS · Multi-part · Fermi University Physics · Earth, Climate & Energy Physics · Energy resources and conversion · Energy resources and conversion

Energy from Physics, Ch The illuminated junction: generation, collection and the cell's characteristic

Problem

A silicon module is rated at standard test conditions (

25^\circ\mathrm{C}

1000\,\mathrm{W\,m^{-2}}

J_{sc}=40\,\mathrm{mA\,cm^{-2}}

V_{oc}=0.691\,\mathrm{V}

\mathrm{FF}=0.844

. Its nominal operating cell temperature is

T_{\rm NOCT}=45^\circ\mathrm{C}

(defined at

800\,\mathrm{W\,m^{-2}}

and

20^\circ\mathrm{C}

air). On a cold, bright morning the irradiance on the module plane is

F_c = 400\,\mathrm{W\,m^{-2}}

and the air temperature is

-5^\circ\mathrm{C}

. Idealise the short-circuit current as proportional to irradiance, take

\mathrm{d}V_{oc}/\mathrm{d}T = -1.7\,\mathrm{mV\,K^{-1}}

for the temperature effect at fixed light level, and take the

59.5\,\mathrm{mV}

-per-decade rule for the effect of light level at fixed temperature, adding the two shifts to

V_{oc}

. ((a)) Find the cell temperature using

T_{\rm cell}=T_{\rm air}+(T_{\rm NOCT}-20^\circ\mathrm{C})F_c/(800\,\mathrm{W\,m^{-2}})

. ((b)) Predict

J_{sc}

V_{oc}

\mathrm{FF}

and the output power per unit area on this cold bright morning, and compare the resulting efficiency (against the incident

400\,\mathrm{W\,m^{-2}}

) with the rated

23.3\%