 |
Here are some quick questions |
|
 |
Give some rough numbers (with some reasoning whereever applicable), always per m2,
for - Maximum solar power.
- Maximum and practical efficiency of "standard" Si solar cells.
- Average power for "standard" Si solar cell.
- Average energy harvest of "standard" Si solar cells per year.
|
| |
Compare indirect and direct semiconductors with respect to light absorption at the "band edge",
i.e. for light energies around bandgap energy. What follows for solar cells? |
|
|
What is your first priority with respect to the coupling of light and semiconductor when you want to make
a solar cell with a good efficiency? |
|
|
Draw the current density (j) - voltage (U) characteristics of a pn-junction
in the dark and under illumination in the interesting part of the j-U plot. Point out the important
points of the illuminated diagram and give some approximate numbers for typical intense sun light. |
| |
The typical j-U equation for a Si pn-junction is |
| |
| j = |
j1 |
· |
æ
ç
è |
exp | eU
kT | – 1 |
ö
÷
ø |
+ |
j2 |
æ
ç
è |
exp | eU
2kT |
– 1 |
ö
÷
ø |
– jPh |
|
|
| |
Discuss the origin of the j terms. Compare (qualitatively) the magnitude of j1
and j2 . What kind of properties of Si influence the value of jPh? |
|
|
Why is "dirty" Si not good for solar cells? Hint:
Follow the fate of a photon-generated carrier. |
|
|
Draw the j-U curve of an illuminated decent solar cell. Draw (qualitatively) the power curve
into this diagram. Discuss the curve shortly with respect to real power applications |
| |
Your electrical energy bill shows that you, personally, consumed 2 000 kWh electrical energy per
year in your home. How man square meters of solar cells (roughly) would you need on your roof to supply this much energy? |
|
|
Give the eqivalent circuit diagram of a realistic Si solar cell. Discuss the components with the
aid of schematic IV-characteristics. |
|
|
Define the fill factor of a solar cell and discuss its dependence on solar cell parameters. |
| | |
© H. Föll (Semiconductor Technology - Script)
8.1.3 Summary to: 8.1 Solar Cells - General Concerns 
With frame