### Solar

This is the wiki for **Engineering**'s *Solar Cells, Fuel Cells and Batteries*.

## Useful constants

```
Planck's constant h
6.626e-34 J*s
4.135e-15 eV*s
Reduced Planck constant
Dirac constant h-bar
1.054e-34 J*s
6.582e-16 eV*s
Mass of an electron m
3.109e-31 kg
Boltzmann constant k_B
1.381e-23 J/K
8.617e-5 eV/K
k_B*T at 300K
4.14e-21 J
2.58e-2 eV
```

## Silicon

```
Valence band density of states Nv
1.83e19 /cm^3
Conduction band density of states Nc
3.22e19 /cm^3
Band gap energy Eg at 300K
1.12 eV
```