Dust accumulation at the border of photovoltaic (PV) panels significantly reduces the power, safety, and economy of PV power generation. However, no quantitative model of the power generation of PV panels with border dust exists. A piecewise single-diode model (SDM) is used to establish a PV power generation model that considers border dust accumulation. The influence of the dust concentration and dust area on the model parameters is investigated. A numerical solution based on a dynamic initial value is proposed to obtain the voltage and power of PV cells at a fixed current. An experimental platform for border dust deposition is built to verify the model performance. The influence of border dust on the power generation of PV panels is discussed. The results show that border dust accumulation significantly reduces the power generation of PV cells. The power loss is 60.13 W (63.30 W) when the border on the PV panel’s short (long) side is covered with 36 g/m2 of sandy soil. Moreover, the impact of dust on the PV power generation differs for dust in different locations. The power loss increases with an increase in the dust concentration and dust area when the dust is on the border of the PV panel’s short side. In contrast, due to bypass diode protection, when dust is on the long side of the PV panel, the power loss will increase and then stabilize as the dust concentration increases. The dust type also affects the PV power generation ability. At the same dust level and location, the power loss is the largest for cement, followed by sandy soil and red soil.