Calculating Solar Energy Generation from GHI, DNI, and DHI Data

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SUMMARY

This discussion focuses on calculating the daily energy generation of a 20 kW solar power system using hourly meteorological data, specifically Global Horizontal Irradiation (GHI), Direct Normal Irradiation (DNI), and Diffuse Horizontal Irradiation (DHI). The calculation method involves using an insolation factor and a yield factor, with the yield factor established at 0.89 for efficiency. Participants provided insights on obtaining average monthly insolation data from the NREL website and NASA's EOS web services, emphasizing the importance of panel orientation in accurate calculations.

PREREQUISITES
  • Understanding of solar energy principles and calculations
  • Familiarity with Global Horizontal Irradiation (GHI), Direct Normal Irradiation (DNI), and Diffuse Horizontal Irradiation (DHI)
  • Knowledge of yield factors in solar energy systems
  • Ability to access and interpret meteorological data from NREL and NASA
NEXT STEPS
  • Research how to calculate insolation using GHI, DNI, and DHI data
  • Learn about the impact of panel orientation on solar energy generation
  • Explore the NREL and NASA resources for solar data retrieval
  • Investigate the significance of yield factors in solar system performance
USEFUL FOR

Solar energy engineers, renewable energy analysts, and anyone involved in solar power system design and optimization will benefit from this discussion.

athar.walile
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Can we calculate the daily energy generation of 20KW power pack if have the following information:


Date Time GHI DNI DHI
01-01-2008 08:00 0 0 0
01-01-2008 09:00 149 398 75
01-01-2008 10:00 348 686 98
01-01-2008 11:00 512 792 112
01-01-2008 12:00 626 845 119
01-01-2008 13:00 674 859 123
01-01-2008 14:00 659 860 119
01-01-2008 15:00 574 827 112
01-01-2008 16:00 431 753 100
01-01-2008 17:00 245 497 106
01-01-2008 18:00 36 63 30
01-01-2008 19:00 0 0 0

Thank you.
 
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athar.walile said:
Can we calculate the daily energy generation of 20KW power pack if have the following information:


Date Time GHI DNI DHI
01-01-2008 08:00 0 0 0
01-01-2008 09:00 149 398 75
01-01-2008 10:00 348 686 98
01-01-2008 11:00 512 792 112
01-01-2008 12:00 626 845 119
01-01-2008 13:00 674 859 123
01-01-2008 14:00 659 860 119
01-01-2008 15:00 574 827 112
01-01-2008 16:00 431 753 100
01-01-2008 17:00 245 497 106
01-01-2008 18:00 36 63 30
01-01-2008 19:00 0 0 0

Thank you.

What is the context of the question? Can you please provide more details? Is this question for schoolwork?
 
berkeman said:
What is the context of the question? Can you please provide more details? Is this question for schoolwork?

Based on in information i have,

Location of Project : Latitude- 26.9° N, Longitude- 72.0° E
Size of Project : 20 KW
Hourly Meteorological Data : Global Horizontal Irradiation, Direct Normal Irradiation, Diffuse Horizontal Irradiation

I want to find out the possible generation of energy for that plant in KW. I have provided the hourly based meteo data.
 
athar.walile said:
Based on in information i have,

Location of Project : Latitude- 26.9° N, Longitude- 72.0° E
Size of Project : 20 KW
Hourly Meteorological Data : Global Horizontal Irradiation, Direct Normal Irradiation, Diffuse Horizontal Irradiation

I want to find out the possible generation of energy for that plant in KW. I have provided the hourly based meteo data.

Here is the solution

Total generation of units (kWh) = Insolation factor x Yield Factor x Total installed capacity
 
Are your panels fixed? What is their orientation?

How are you using the GHI, DNI and DHI to arrive at a value of Insolation, and is this data your own?

Can you expand upon what Yield Factor incorporates?
 
Zryn said:
Are your panels fixed? What is their orientation?

How are you using the GHI, DNI and DHI to arrive at a value of Insolation, and is this data your own?

Can you expand upon what Yield Factor incorporates?

Yield factor is 0.89

Little confused about using GHI, DNI and DHI values in my insulation calc. but i m using GHI in my calculation. I am not aware of how to use meteorological data here.

I got this data from NREL website: http://rredc.nrel.gov/solar/new_data/India/nearestcell.cgi?
 
Find out your Latitude & Longitude:

http://www.whatsmygps.com/"

Find your Insolation:

http://eosweb.larc.nasa.gov/cgi-bin/sse/grid.cgi?email"

  1. Sign up (its free)
  2. Enter your Latitude & Longitude
  3. Select the data you want ('Average Insolation' only will suffice)

You now have your average monthly Insolation.

Alternatively you can calculate the contribution from GHI, DNI and DHI to your Hourly Insolation relative to the orientation of your solar panel(s) and get much more accurate specific site data, but if you don't need it, the NASA information is a good enough approximation.

So if you have a 2kW system, and have 5 Hours Insolation, you can expect to get (2kW * 5H =) 10kWH from your system that day.

I assume the Yield Factor is an expression of efficiency, so at 89% you would end up with (10kWH * 0.89 =) 8.9kWH instead.

At $0.20 per kWH you would have made/saved (8.9kWH * $0.20 =) $1.78 that day!
 
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