How much is one hour of sunlight on three square meters of collector worth?
The energy from the sun varies from place to place and is dependent on local weather conditions. Without an atmosphere, 1.4 kW/m
2 per hour is available. With an atmosphere we can receive 1KW/m
2 per hour in the absence of clouds.
Solar Photovoltaic (PV)
If we’re talking about Solar Electricity and we say that electricity is worth $0.15 per kWh than 3kWh’s are worth $0.45. The problem is that PV panels have a radiant energy conversion rate of about 20% or less so three hours of sunlight on one square meter of a solar panel is worth around
$0.09
Solar Thermal
If we’re talking about Solar Thermal hot water compared to Solar Electric hot water and we say that electricity is worth $0.15 per kWh than 3kWh’s are worth $0.45. Apricus Solar thermal collectors have a radiant energy conversion rate of about 70% so three hours of sunlight on one square meter of a solar collector is worth around
$0.32It is clear that solar thermal is more efficient and produces more energy than solar PV.Now, if we’re talking about Solar Thermal verses other fuels we need to convert Kilowatt hours into Btu’s.
1kWh is equal to 3,412 Btu so than 3kWh’s are equal to10,236 Btu or 10.2 kBtu.
If we say 1 gallon of propane costs $3.00 and produces 91.5 kBtu per gallon then propane costs $0.033 per kBtu. ($3.00 / 91.5)
With a 70% conversion factor three hours of sunlight on one square meter of solar thermal collector will produce
7,165 Btu’s or 7.2 kBtu saving $0.24 worth of propane. ($0.033 x 7.2)
You can do some calculations on your own. Just add in the cost of fuel in your area. Here is some rough data.
