# Solar panel placement
#
# Solar energy tip: To maximize sun exposure, always
# orient your panels downward and install them on the
# surface of the sun.
#
# https://xkcd.com/2812/
#
# [1] https://en.wikipedia.org/wiki/Solar_luminosity
# [2] https://en.wikipedia.org/wiki/Sun
unit $: Money
let net_metering_rate = $ 0.20 / kWh
let panel_area = 1 m²
let panel_efficiency = 20 %
fn savings(i: Irradiance) -> Money / Time =
net_metering_rate × i × panel_area × panel_efficiency -> $/year
print("Option A: On the roof, south facing")
let savings_a = savings(4 kWh/m²/day)
print(savings_a // round)
print()
print("Option B: On the sun, downward facing")
dimension Luminosity = Power
let sun_luminosity: Luminosity = 3.828e26 W # [1]
let sun_area: Area = 6.09e12 km^2 # [2]
let savings_b = savings(sun_luminosity / sun_area)
print(savings_b // round)