This paper presents a novel obstacle and inclination detection technique for Macao world heritage district photovoltaic system utilizing Google Earth's Geographic Information System (GIS) and 920-MHz Ultra-High Frequency Radio Frequency Identification (UHF RFID). For larger solar energy capacity required in heritage protection and development, the vertical solar panel attached to the building wall is considered; the solar panel is attached with a UHF RFID tag with a transparent 3D hollow substrate. A barrier between the tag and reader can drastically reduce the effective area of the tag antenna and; its signal received. The 3D hollow substrate is filled with liquid; the liquid flows with panel inclination establishing a perfect conductor plate (PEC) for the tag antenna. Such PEC disables the tag operation, allowing a vertical solar panel inclination safety detection in operation. The tag's Received Signal Strength Index (RSSI) experimental trial shows a difference of more than 10 dB between situations with and without obstructions. The inclination safety with 20 degrees deviated from 90-degree normal installation is verified by RSSI change from -67 dBm to -85 dBm. The ability to identify obstacles that are casting shadows on or covering solar panels is a straightforward and cost-effective solution for photovoltaic systems; effective inclination safety can be simply applied.