Units and Conversions

See also Constants


Energy and Power Conversions
1kWh 3.6 × 106 J
1 hp (horsepower) 746 W
1 Btu 1.055 kJ
   

Time Conversions
1 year 8765.8 hours
1 hour 3600 sec
1 year 3.157 x 107 sec
   

Solar Radiation Conversions
1 kWh/m2 1 Peak Sun Hour
1 kWh/m2 3.6 MJ/m2
1 kWh/m2 0.0116 Langley
1 kWh/m2 860 cal/m2
1 MJ/m2/day 0.01157 kW/m2
1 kW/m2 100 mW/cm2
   

Miscellaneous
1 ft2 0.093 m2

1 m2 is approximately 10 ft2

Standard SI prefixes

Symbol Prefix Factor
T tera 1012
G giga 109
M mega 106
k kilo 103
c centi 10-2
m milli 10-3
μ * micron 10-6
n nano 10-9
p pico 10-12

* occasionally um is used instead of μm for microns