0.5 - 1 V

1 - 2 V

2 - 3V

4 - 5 V

solar cell

fuel cell

Edison cell

cryogenic storage

0.5 W

1.0 W

5.0 W

10.0 W

series arrangement of solar cells

parallel arrangement of solar cells

series-parallel arrangement of solar cells

none of the above

low efficiency

lack of availability

high cost and maintenance problems

all of the above