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#1
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sabirrahman rahman
12-29-2013 09:02 AM

How to find solar sunhour/day using solar irradiation values?

can any one guide me how to find solar sunhour/day using solar irradiation values for a particular site and  finding optimum angle of module facing in order to get maximum in fixed mounting
12-29-2013 11:16 AM
Top #2
Dinesh More
12-29-2013 11:16 AM
To find Sunhours/day, 1. u need to have the solar irradiance values for every 10 minutes intervals of the day. 2. Note the time interval for which solar irradiation remains significant say..200w/m2 and above for the day. 3.Multiply this time interval (in hrs) with the average of the irradiance values noted throughout the day. 4. u will get the incident solar energy (kwh/m2) 5. Now when we divide this incident solar energy by the reference irradiance which is 1KW/m2 to get the no of peak sun hours.
12-29-2013 01:53 PM
Top #3
Abdulaziz Mohammed Baras
12-29-2013 01:53 PM
I suggest to try PVGIS database or PVsyst software.
12-29-2013 03:59 PM
Top #4
Ron Franklin
12-29-2013 03:59 PM
Sounds to me that NABSEP training would be of value??
12-29-2013 06:03 PM
Top #5
sabirrahman rahman
12-29-2013 06:03 PM
thanks dinesh more and abdul aziz baraz can i use nasa solar data as base what are the latest measuring instruments available for site survey condition
12-29-2013 08:54 PM
Top #6
Bhuwenesh Gupta
12-29-2013 08:54 PM
Hi Sabir, Yes you can use the Nasa solar database which is freely available on internet (http://eosweb.larc.nasa.gov/sse/). Here you can select the GPS co-ordinates and get the irradaition data.

But be aware that this data is not based on surface solar data usually collected using pyranometer (http://en.wikipedia.org/wiki/Pyranometer).

The Nasa data is an estimation of solar irradiation based on the satellite measurements of weather behavior on various parts of earth.

So the Nasa data maybe not precise. But in absence of any other reliable data sources one has to use it.

There are few weather stations which are installed all over India which can provide more precise information but more likely than not they are not going to give you better data for your particular site.

You can definitely procure automatic weather station for wireless solar meter and weather monitoring for your site survey.
12-29-2013 11:45 PM
Top #7
Mark Veach
12-29-2013 11:45 PM
You solar 'professionals" are scaring the crap out of me... I guess not all countries have permiting and inspections.
12-30-2013 01:57 AM
Top #8
Bhuwenesh Gupta
12-30-2013 01:57 AM
Hi Mark,

I fail to understand how permitting and inspection would impact the expected solar sunhour/day of a site? Maybe you can explain.
12-30-2013 04:31 AM
Top #9
Sean Anderson
12-30-2013 04:31 AM
If in the US, go to NREL website, then National Solar Radiation Database to obtain TMY3 (Typical Mean Year) data from hundreds of sites. Each dataset is composed of numerous years of data, giving the typical mean year data.
Finding the optimum tilt angle depends upon solar radiation data, spacing (closeness of rows of PV modules), and environmental shading. Using software such as PVsyst can allow you to define the system, and then run simulations with different row spacing and tilt angles to determine the optimum angle.
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