Calculation of daily solar insolation

In summary, the difference between online calculators and the calculations performed in this document is that the online calculators take into account the effects of albedo.
  • #1
jones123
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0
Hi all,

I'm trying to calculate the daily solar insolation (integrated solar irradiances from sunrise to sunset) for a given location and day of the year. For latitude 43.2° and April 15th, I get:

H0 = (solar constant * scale factor for intra annual variation of sun-earth distance * 86400 seconds/pi) * (cos(latitude) * cos(declination) * sin(hour angle sunset) + (hour angle sunset * pi/180)*(sin(latitude)*(sin(declination))

or with numbers:

H0 = ((1368*0.99226178414418)*(86400/pi))*(cos(43.2°)*cos(9.6423°)*sin(99.1805°)+(99.1805°*pi/180)*sin(43.2°)*(sin(9.6423°)) = 3.39E7 J/day.m2

However, when I try to check the result with online calculators, they say the result should be 2.65E7 J/day.m2 ...

Can anyone please check and help me out if and what I am doing wrong? It would be of very great help!

Thank you!
 
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  • #2
I can't say I entirely follow your calculations, but the end result difference looks in the ballpark of what you'd get if you corrected for albedo - which you don't seem to have done.
 
  • #3
Bandersnatch said:
I can't say I entirely follow your calculations, but the end result difference looks in the ballpark of what you'd get if you corrected for albedo - which you don't seem to have done.
Hi, calculations were based on Part 4: Irradiation Calculations | ITACA:

upload_2017-7-17_13-51-47.png
 
  • #4
jones123 said:
However, when I try to check the result with online calculators, they say the result should be 2.65E7 J/day.m2 ...
What calculators are these? I'm getting 3.39E7 out of wolfram alpha.
 
  • #5
Bandersnatch said:
if you corrected for albedo
What albedo?
 
  • #6
sophiecentaur said:
What albedo?
Having no context for the question, I assumed the calculations were for energy available at the surface at some location, which must take into account the amount of energy reflected. The context provided later has shown that this is but an intermediary step, and such effects are taken account for later on.
 
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  • #7
Bandersnatch said:
Having no context for the question, I assumed the calculations were for energy available at the surface at some location, which must take into account the amount of energy reflected. The context provided later has shown that this is but an intermediary step, and such effects are taken account for later on.
So it's not something that you could use for a general calculation. The 'real' answer must depend on the actual site, weather and time of year. A survey would be needed, I suppose.
 

1. What is daily solar insolation?

Daily solar insolation refers to the amount of solar radiation that reaches a specific location on a given day. It is typically measured in watts per square meter (W/m^2).

2. How is daily solar insolation calculated?

Daily solar insolation is calculated using a formula that takes into account the angle of the sun, the duration of sunlight, and the atmospheric conditions at a specific location. This calculation can be done manually or using specialized software.

3. Why is daily solar insolation important to study?

Daily solar insolation is important to study because it affects various aspects of our lives, including agriculture, energy production, and climate. Understanding and predicting changes in solar insolation can help us make informed decisions and plan for the future.

4. What factors can affect daily solar insolation?

Several factors can affect daily solar insolation, including the Earth's tilt and rotation, atmospheric conditions (such as clouds and pollution), and topography (such as mountains and valleys). The time of year, latitude, and longitude also play a role in determining the amount of solar radiation that reaches a specific location.

5. How can daily solar insolation be used in practical applications?

Daily solar insolation can be used in various practical applications, such as determining the optimal placement and angle for solar panels, predicting crop yields, and designing energy-efficient buildings. It can also be used in climate studies to understand the effects of solar radiation on temperature and weather patterns.

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