How to find the best solar panel tilt angle?

hi to all,
i gone start to build a house next year in the Philippines but i have a problem to find the right roof angle
i use a calc.method that is using the next but i am not sure if this is the right one for near the equator
for wintertime,multiplying the latitude by 0.9 and then adding 29°
for summertime, " " " " " " " subtracting 23,5°
my latitude is 7.44(Pitogo) but if i use this then i have for winter 35° and summer -16,8°
i taught it must be all facing south if we live in the north but summer look strange:smiley:
can someone tell me if this is right or what angle should i use at best

Hi Marco

I use this site for best angle of panels, and different outputs from angles

In northern hemisphere the panels should face south, but near the equator the sun is almost straight over head, so you want a low angle, like 10 degrees. However, if you have a greater angle, you will generate more power in the winter, so it depends whether you want best full year production, or more power in summer, or winter, if that makes sense.


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thanks Marty,

i gone order that book to understand more of it, so that i know what i am doing
for me it’s a little bit confusing that the angle is south and north
but if i am right it’s gone be ask more calculation due to the ideal angle from 58° to 106° all over the year
but right now from what you said about 10° maybe i gone do it with a butterfly roof at that angle from 10°and panels on both sites


Hi Marty,

The rule of thumb is to mount the PV modules (panels) at the latitude of your locations. There are some caveats.

  • It is a good idea to have the panels at about 10°, even if near the equator. This prevents water from pooling, that contributes to soil and even mold build up.
  • The weather impacts production. For example, Sacramento CA is about 40°. Setting the panels at this angle is best for winter, but in the winter it rains, so a better angle is actually about 26°.

The way to find is use
There is weather data for Manila. Select Manila and enter a proposed angle (along with other data) in the next page.
Run the simulation at different angles and see what energy you can harvest.



Hi Marco;
I don’t have anything to add to this thread as I am new to solar, but I noticed that you are building your solar system in the Philippines, where I am also planning to build my retirement home. Have you selected your solar panels and charge controller yet? If so, what have you selected and why? Are you planning a DC coupled system or hybrid with grid tie? Really appreciate any recommendations that you could share! Selamat!

sorry chewface for delay,(was reading the book)
i gone use a AC coupled off grid system
it’s look more like this
panels: sunpower,panasonic,lg or … for a total of about 7kWh,not decide yet,look what is available on the time i build it
fronius inverter and a selectronic inverter/charger
and batteries from Hoppecke(well know in Germany)
but it’s gone be delayed bcse they gone start there on a big new road and i gone wait to it’s done
so that’s how it’s look now but for example batteries it can change,see what the future bring:)
i heard that sunpower have a factory in the Philippines,so that could be maybe first choise

Good conversation…

As @xetdog said the best tilt angle is roughly the latitude of your location. I have put together the image below for all the Aussie readers who often place their panels as flat as possible. The southern states are quite far south of the equator (at 37 degrees) which means the optimum tilt angle is around 30 to 37 deg.
Note: the higher tilt angle will also cast a long shadow in winter so rows of panels need to be spaced up to 3 meters apart to avoid shading (on a flat roof). If the roof pitch is 20deg like most homes, it’s common practice to place the panels flat on the roof to fit more panels and avoid shading.

For off-grid systems you would want to maximise winter performance by tilting the panels closer to 40 deg. This is because the solar radiation is much lower during winter as the sunlight has to travel through more of the atmosphere and loses energy.

Note for normal grid-connected systems the tilt-angle is generally not critical and the panels are usually placed flat on the roof which is typically 18 - 22deg pitch. This will provide good all year round performance in most states unless you live very far south in which case it might be worth while tilting slightly (this will of course add to the installation cost)

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