Jesse Posted July 11, 2019 Share Posted July 11, 2019 I have three 300W solid panels installed directly on normal minirails on a 34 degree roof pointing directly Northeast in Swellendam [latitude 34 degrees]. I want to add some new panels and could put them on special rails that orient them to the north, but I hesitate doing so because of cost, aesthetics and extreme wind conditions. In order to make a more informed decision regarding the cost I would like to calculate the efficiency loss from orienting any panel to the Northeast vs directly north [assuming the same tilt]. I've looked on the web, but only found generalizations saying that it's better to point them north, and that a few degrees off won't matter much, but no hard calculation that can determine the difference if 45 degrees off of north. Can anyone help me with this? Quote Link to comment Share on other sites More sharing options...
Jesse Posted July 11, 2019 Author Share Posted July 11, 2019 PS After posting this I found the following website: https://solarcalculator.com.au/solar-panel-orientation/ which tells me that I would lose 15% efficiency if pointing east [since Sydney and Swellendam have the same latitude]. This would seem to indicate that a northeast orientation would likely result in only a 7 or 8% loss. It also mentions that if not facing north a more horizontal tilt would give better performance, and I do have a porch roof just below my existing panels that is only 12% that would seem to be a better location. Any comments and/or suggestions on the above? Quote Link to comment Share on other sites More sharing options...
Jesse Posted July 14, 2019 Author Share Posted July 14, 2019 Not much response on this one, so I put in another 10 hours of web hunting and found this site that gave me exactly what I needed: https://pvwatts.nrel.gov/pvwatts.php hopefully it will help others as well, no matter where in the world they may be demaniak 1 Quote Link to comment Share on other sites More sharing options...
Tariq Posted April 14, 2020 Share Posted April 14, 2020 (edited) Hi Jesse, I have the same situation as yours am in Cape Town, have a carport that runs northeast, so I would have to figure out the ideal, pointing due North and at 34 degrees tilt versus flat is 10 % drop in efficiency, I have a 2.2 kw array, so that is a loss of 1 kWh per day, to make life simpler and less costly, think that is what I will do. How did you make out, did you use the porch ps thanks for the research Tariq Edited April 14, 2020 by Tariq Quote Link to comment Share on other sites More sharing options...
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