Search results for solar rooftop price are crowded with home-system packages. Factory buyers should compare total installed scope, not a single baht-per-watt number.
What a serious factory quote usually includes
Modules, inverters, mounting, main-board tie-in, cabling, testing documents, and site safety. If any of those sit outside the price, a “cheap” bid often grows later.
Why plants cost more than houses
High roofs, HVAC shade, aging main boards, and short shutdown windows all add cost that residential jobs rarely face. Ask vendors to split structure and electrical from module supply.
How to compare fairly
Lock the same scope, similar equipment class, and clear ownership of roof reinforcement, waterproofing, and as-built handover—then compare numbers.