Dear Aung,

There is an interesting recent study on the orientation of the solar arrays and the relation of their optimum value to the latitude: World estimates of PV optimal tilt angles and ratios of sunlight incident upon tilted and tracked PV panels relative to horizontal panels

Please follow the paper at the link: https://web.stanford.edu/group/efmh/jacobson/Articles/I/TiltAngles.pdf

Best wishes

In the past, panel manufacturers would not offer warranties on panels installed at an angle lower than 2 degrees, but these days most of the top manufacturers will give warranties even if their panels are installed at 0 degrees (completely flat).

Source: https://www.solarchoice.net.au/blog/flat-solar-panels-vs-tilted

5 Things To Know When Installing Flat Roof Solar Panels

Source: https://blog.pickmysolar.com/5-things-to-know-when-installing-flat-roof-solar-panels

If fixed structures of solar-PV arrays are adopted, then it is known the near optimal tilt angle equals to the latitude of the placement site. Significant deviation from this tilt angle will cause noticeable reduction in the power/energy production.

Note: zero or near tilt angles are then very normal at many locations on the Earth. At, and near tge equator are examples of such locations.

I am kindly inviting you to read the following articles especially the first one.

https://www.researchgate.net/publication/273178841_Photovoltaics_energy_Improved_modeling_and_analysis_of_the_levelized_cost_of_energy_LCOE_and_grid_parity_-_Egypt_case_study?_iepl%5BviewId%5D=kIoTEOLyCdt3OltgzfmhhnwJ&_iepl%5BprofilePublicationItemVariant%5D=default&_iepl%5Bcontexts%5D%5B0%5D=prfpi&_iepl%5BtargetEntityId%5D=PB%3A273178841&_iepl%5BinteractionType%5D=publicationTitle

https://www.researchgate.net/publication/311536347_IRRIGATION_WATER_PUMPING_IWP_SYSTEMS_-_COMPARISON_BETWEEN_PHOTOVOLTAICS_AND_CONVENTIONAL_ENERGY_SOURCES?_iepl%5BviewId%5D=0148xshDicfmJQF1BHWqtuO8&_iepl%5BprofilePublicationItemVariant%5D=default&_iepl%5Bcontexts%5D%5B0%5D=prfpi&_iepl%5BtargetEntityId%5D=PB%3A311536347&_iepl%5BinteractionType%5D=publicationTitle

https://www.researchgate.net/publication/239792384_Sizing_optimisation_of_stand-alone_photovoltaic_generators_for_irrigation_water_pumping_systems?_iepl%5BviewId%5D=NHRVe9q80ueYT7dqkZbsByqN&_iepl%5BprofilePublicationItemVariant%5D=default&_iepl%5Bcontexts%5D%5B0%5D=prfpi&_iepl%5BtargetEntityId%5D=PB%3A239792384&_iepl%5BinteractionType%5D=publicationTitle

Your feedback will be appreciated.

Hello Prof. Mohamed EL-Shimy,

I'm really great pleasure for your valuable answers.

Big Thanks!!!

Sincerely,

Prof. Ze Ya

Thank you Prof. Ze Ya for your feedback.

You can study performance of PV of any tilts by the help of online calculator, such as PV-watts, or PV-GIS

http://re.jrc.ec.europa.eu/pvg_tools/en/tools.html

http://pvwatts.nrel.gov/pvwatts.php

the angle of the solar cell is the main factor which effect on the performance of cell

Thanks a lot !!!

Hello Prof. Ze Ya,

There have already been a number of very good inputs to this discussion. The references from Vladimir Kubov give two valuable calculators that can be used to determine panel output based on tilt. Another useful calculator can be found at

http://solarelectricityhandbook.com/solar-angle-calculator.html

However, the discussion might also gain from the advantage of considering several other site specific factors.

If you are considering a horizontal panel orientation, you can see from the calculators that at 45 degrees latitude (north or south), there will be less impact (loss) in summer time, when the optimal angle might be near to horizontal, say 20 degrees, than in the winter when the optimal angle will be closer to 70 degrees. (The annual average is about the latitude).

Here in Canada, and in any other location where snow is a factor, a horizontally oriented panel would suffer large losses on days when snow occurs, and until the panels are cleared. In this situation, it can be an advantage to actually select a higher tilt angle than the optimum winter value to make it easier for snow to shed from the panels. As an example, the winter sun angle might be low at noon, so the calculator suggests for our location at 45 degrees north, an optimum angle of 22 degrees in December, but 70 degrees in July. But, to prevent snow sitting on the panels, really the optimum angle in snowy months - perhaps November through March, can be closer to 20 degrees, even though the calculator would suggest values of 38 degrees in October and February.

On a similar vein, even in areas without snow accumulation, a horizontal panel is far more likely to suffer loss from build up dirt and dust, while an angled panel is more likely to "self wash." The calculators tend to just use a fixed value of loss fro,m snow or dirt, but in reality it can be very variable.

On the other hand, if a panel will have only one fixed tilt value, recognize that a horizontally oriented panel presents less wind load that one with a high tilt, and may be less likely to suffer damage. Hope these considerations may help you to realise that it is not as simple as a text book calculation.

All the best in your project.

William Palmer

Hello Prof. William Palmer,

I'm really acknowledge for your very deep and valuable answer.

So, in Central Part of Myanmar, it always sunny and mostly No Snow.

Therefore, in some villages, the villagers are using only flat installation.

Then, it's correct or not?

Very sincerely

The Myanmar latitude is 10N to 27N. So optimum tilt is 10 to 27 (relative to horizon) . This tilt is near flat installation.

And more details are in William Palmer answer

Hello Prof. Valadimir Kubov,

Thanks a lot for your valuable answer.

Best

I completely agreed with Mr. Muhamed El shimy.

Regards

Hello again, Prof. Aung Ze Ya,

Your case is certainly different than here in Canada. (I might add I did a tiny bit of searching images of Central Myanmar of which I have no experience, and it is a very beautiful looking country.) I assumed Nay Pyi Taw as representing central Myanmar, at about 20 degrees north latitude. The solar electricity handbook (noted above) shows optimum tilt for solar panels (relative to sun angle) at 94 degrees in June (slightly past horizontal, angled ever so slightly north), 86 degrees in May and July, 78 degrees in August and April, 70 degrees in March and Sept, 62 degrees in Feb and Oct, 54 degrees in Jan and Nov, and with an extreme tilt level of 46 degrees in December. That's much different than the more severe angles I had spoken of to shed snow, but that would not seem to be an issue for you other than in mountainous regions. I'm assuming that you plan to use a fixed tilt to avoid the need to readjust it seasonally, although if that was a possibility it might given an opportunity for panel washing and tilt adjustment perhaps twice a year in March and September, tilting them to perhaps 60 degrees in September, and then to 80 degrees in March. I also note that at a latitude of 20 degrees north, your kWh of insolation will vary little from season to season, shown as about 7.12 kWh per square meter in December, 9.75 kWh per square meter in March and September, and 10.99 kWh per square meter in June.

Another factor you will need to consider is if your expected load on your solar panels varies much from month to month. For example, is there any need for additional refrigeration or cooling fans in the peak of summer, or is the load fairly equal through the year? If you find that your load was equal through the year, then you might want to tilt your panels somewhat towards the 70 degree value suggested for March and September, which will lower your June output somewhat, but raise your December output a bit. That would give you some output leveling, and also would give some minor tilt that would help the panels to self wash a bit.

Even though the absolute maximum panel output might seem to be possible with the 94 degree tilt (slightly past horizontal to tilt slightly north) for the June setting, that would result in losses in the other months and would seem to be undesirable.

Beyond that, incalculables enter the picture such as annoyance of reflection from the panels depending on the tilt, onto nearby windows, or highways, where they might even create a hazard at some times of day. It seems that I usually add more questions for you to think about, and less simple solutions.

I suspect you now have the tools you need to select the optimum setup for your particular situation though.

All the best,

William Palmer

Hello Prof. William Palmer,

I'm very very thankful for your deeply and invaluable answer.

Very sincerely

Dear Researcher,

the below two papers gives the detailed information on the performance of the PV system when it mounted at flat or horizontal or zero tilt.

Please refer them, they will be help full.

Conference Paper Performance Comparison of Building Integrated Multi-Wattage ...

Conference Paper Estimation of Grid Feed in Electricity from Roof Integrated ...

Thank you and all the best...!!

Regards,

Nallapaneni

Hello Nallapaneni,

Thank you so much.

Best regards

Dear Aung,

There is an interesting recent study on the orientation of the solar arrays and the relation of their optimum value to the latitude: World estimates of PV optimal tilt angles and ratios of sunlight incident upon tilted and tracked PV panels relative to horizontal panels

Please follow the paper at the link: https://web.stanford.edu/group/efmh/jacobson/Articles/I/TiltAngles.pdf

Best wishes