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Before getting a solar quote, assess your own roof. A good assessment prevents expensive surprises — structural reinforcement costs, low-output installations due to wrong orientation, or shade problems that no installer mentioned. Here is the 8-point checklist used by professional solar engineers.
The 8-Point Roof Assessment
Check | What to Look For | Philippine Standard |
|---|---|---|
1. Orientation | South-facing is best; North-facing acceptable; East/West loses 15-20% | South or North-facing preferred |
2. Tilt angle | 10-25° ideal for Philippines (latitude 5-20°N) | Minimum 10° for self-cleaning |
3. Shading | Trees, water tanks, antennas, neighboring buildings | Zero shading 8am-4pm ideal |
4. Roof age | Remaining life should exceed 15 years for full system life | Replace if under 5 years old |
5. Roof material | Corrugated G.I., concrete deck, clay tiles, standing seam | All types supported — different mounting hardware |
6. Structural capacity | Panels add 12-15 kg/m² load | Most Philippine concrete/steel roofs adequate |
7. Usable area | Minimum 20m² for 3kW; 35m² for 5kW; 65m² for 10kW | Allow 2m² per 300-400W panel |
8. Electrical panel location | Distance from roof to main panel affects cable cost | Under 30m preferred |
Shading: The Most Underestimated Issue
A shadow covering just one cell of one panel in a string can reduce the entire string's output by 20-40%. Before your installer visits, observe your roof hourly from 7am to 5pm on a clear day. Note anything that casts a shadow on the roof area.
Roof Orientation in the Philippines
The Philippines is in the Northern Hemisphere (5-20°N latitude). South-facing panels receive maximum direct irradiance. For a Meralco-area home:
South-facing: 100% output reference
North-facing: 88-92% of south output (still good)
East-facing: ~80% of south output (morning production only)
West-facing: ~80% of south output (afternoon production only)
East + West split: Best for self-consumption — production spread throughout the day
Submit your roof details at solarenergyph.shop and get a verified installer to do a formal site assessment.
Engr. Jason Morales — Founder, SolarEnergyPH