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 https://pvwatts.nrel.gov/
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.
P~