The deposition of dust on the surface of a solar panel affects the power generation of the solar panel and even shortens its service life. Thus, it is necessary to evaluate the effect of dust deposition on power generation quantitatively. We designed an automatic dust measurement platform with a micro-weather station that can be installed on the solar panel to evaluate the effect of dust deposition on the solar panel. The platform comprised a glass cover, a programmable logic controller (PLC), light transmittance sensors, and a sliding rail motor, and measured the irradiance and light transmittance every 10 s. We compared the measured values with the generated power of the solar panel. To understand the effect of dust deposition, we installed two solar power generation systems with measurement platforms at the same location. One platform was cleaned daily and maintained a light transmittance of 94%. The other platform was left without cleaning for 3.5 days. Then, measurements were carried out on the two solar power generation systems from 8:00 AM to 5:00 PM on a sunny day and a cloudy and rainy day. On the sunny day, dust deposition decreased the light transmittance from 94 to 87.36% (an average of 25 measuring points), resulting in a 2.14% decrease in daily cumulative power generation. On a cloudy day, the average light transmittance decreased to 51.40%, and the daily cumulative power generation decreased by 10.83%. These results confirmed that the effect of dust deposition on power generation was more significant than that of weather, and that cleaning the dust was beneficial to power generation. It was found that the automatic dust measurement platform could be used effectively to monitor dust deposition on the solar panel. The results of this study can be used as the basis for installing and managing solar panels so as to achieve their effective use.