Buy the roof layout, not a single module in isolation
Panel choice is partly a module decision and partly a geometry problem. The same roof may fit more total DC power with a physically smaller high-efficiency module even if another module has a higher individual wattage.
Five numbers that deserve attention
- Rated power: useful for array nameplate capacity.
- Efficiency: important where roof area is constrained.
- Dimensions: determine actual layout.
- Temperature coefficient: helps compare hot-condition performance.
- Warranty/degradation: describes long-term commitments, not guaranteed project output.
Manufacturer bankability is not the same as panel quality
Large manufacturer scale can improve availability and support, but a buyer should still verify the specific model, certifications, warranty entity and local claim process.
For an initial array estimate, use the system-size calculator.