Illuminance estimation is key to daylight responsive lighting, and accurate estimation of illumination on workplane requires multi-point illumination, which requires distributed measurement techniques. With as few technical components as possible, we present a lightweight solution of distributed illuminance measurement to accelerate system development. Based on the open source technology, Arduino, we develop porotype of the system, including sensing unit, clock unit and storage unit, without communicating unit different from common distributed measurement. We construct device to calibrate sensing unit with three kind of correctors, and compare the difference of the measurements. Based on absolute time synchronization, we synchronize illuminance by the specified time according to the measurement interval. We carry out the experiments on illuminance estimation to verify that it cannot be completely solved with one single illuminance ratio, although it works well under some specific circumstance.