Solar Energy Calculator
Using this energy calculator you may determine how much energy a SunSurfs solar collector will produce each day/month/year. The way you utilize this energy is up to you. You can heat water for showering and washing clothes, or central heat a building. In fact one integrated system can complete both these functions.
You can also use these values to help you calculate how much energy you can save by using an SunSurfs solar collector.
In order to calculate energy output you must input the following variables:
Insolation Level - Before you
calculate your energy output, you must know your solar
insolation level. This are available from the insolation page. Take note of your max and min levels throughout the year
as well as the annual average value. When assessing potential
energy savings, input annual average insolation, and take note
of the "per year" energy output value.
Energy must be
input in the unit kWh/m2/day. 1 kWh/m2/day = 317.1 Btu/ft2/day
Collector
Size - You must enter the collector size in absorber
surface area.
The absorber surface area of the various
tubes sizes are as follows:
- 58/1800 = 0.08m2 per tube. Therefore an
SunSurfs 20 tube = 1.6m2 absorber area
- 58/1500 =
0.067m2 per tube
Energy Cost - Enter cost per kWh in your local currency
(may need to convert from m3 or Therms)
1 therm = 29.3kWh = 100,000Btu = 105.5MJ
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 Per Month = kWh Per Year = kWh |
=
Btu = Btu = Btu
|
= $/£/€
= $/£/€ = $/£/€ |
|
Please
note:
- Collector peak
efficiency is only achieved when ambient temperature and water
temperatures are the same. During normal use, this is only
likely to happen for a short period of time each day, and
usually only when ambient temperatures are high (summer).
Therefore during normal use, the solar collector can not
always perform at such a high level of efficiency. This is
true for all evacuated tube and flat plate collectors, not
only SunSurfs collectors. In order to provide more realistic
figures, the above calculations are based on "normal"
operating conditions under which the difference between
ambient temp and manifold water temp is around 30-40oC.
- When making comparisons with
other products please take the above point into consideration.
Do not simply use the peak efficiency values for energy
output, as this will provide inflated figures. IAM values also
play an important role in determining total energy output from
a solar collector. Please click
here to learn more about how to interpret IAM
figures.
- Monthly and annual values are calculated
using 28 days and 336 days respectively to account for days of
very low solar radiation.
- Energy output values are
approximations. Actual energy output and overall system
efficiency will depend upon installation location, climate,
insulation, system configuration and many other factors. On
rainy or heavily overcast days energy output will be greatly
reduced.
- Energy is produced in the form of heat. In
transporting and converting this energy, such as for air
conditioning or central heating, some energy (heat) will be
lost, as no system or insulation is 100% efficient. Solar water heaters reduce the need for conventional water heating by about two-thirds. It minimizes the expense of electricity or fossil fuel to heat the water and reduces the associated environmental impacts.