To calculate energy output, follow the instructions:

1) Find the insolation level for your area. Note the maximum, minimum and average insolation levels throughout the year. For potential energy savings calculation, input annual average insolation. Insolation units are expressed in (kilo watt hour per square meter per day) -  1 kWh/m2/day = 317.1 Btu/ft2/day

2)  Enter the collector size in absorber surface area by multiplying the absorber surface area of the evacuated tube by the number of tubes in the collector:
Usually 0.08m2 per tube x number of tubes.

3) Energy Cost - Enter cost per kWh in your local currency
    Natural Gas is 39MJ/m3 = 10.83 kWh/m3
    LPG Propane (liquid) = 25.3MJ/L = 7kWh/L
    LPG Propane (gas) = 93.3MJ/m3 = 25.9kWh/m3

Insolation Level =		kWh/m2/day
Absorber Area =		m2
Electricity Cost =		$ per kWh
Energy Output:
Per Day =		kWh	=Btu	= $
Per Month =		kWh	=Btu	= $
Per Year =		kWh	=Btu	= $