Device and method for measuring effect of soiling on photovoltaic device

A method for spatially resolving soiling non-uniformity on a photovoltaic device, comprising the steps of:

• making measurements of at least one electrical parameter of a single photovoltaic device corresponding to the photovoltaic device's effectiveness in generating electricity in response to exposure to illumination in three different states, the measurements being made sequentially in a single measurement cycle, the first state being with the photovoltaic device unobstructed and exposed directly to illumination, the second state being with the photovoltaic device disposed in a compartment exposed to illumination through a transparent cover cleaned regularly, and the third state being with the photovoltaic device disposed in a compartment exposed to illumination through a transparent cover on which natural or simulated soil is permitted to accumulate without cleaning;
• in the third state, systematically stepping the single photovoltaic device through cells of an m×n Cartesian coordinate grid corresponding to areas of the transparent cover on which natural or simulated soil is permitted to accumulate without cleaning while making the measurements of the at least one electrical parameter in each of the cells, wherein m and n are each integers greater than or equal to one;
• calculating a soiling ratio (SR) from the at least one electrical parameter measured in each of the cells to define a 2-dimensional matrix of soiling ratios corresponding to Cartesian locations (i,j) in the compartment in which the single photovoltaic device is exposed to illumination through the transparent cover on which natural or simulated soil is permitted to accumulate without cleaning, wherein i and j are each integers such that 1≤i≤m and 1≤j≤n;
• and
• comparing the calculated soiling ratios in the 2-dimensional matrix to identify areas of the transparent cover on which natural or simulated soil is permitted to accumulate without cleaning where non-uniform distribution of soiling increases risks of electrical mismatch between interconnected solar cells, hotspots, and other photovoltaic device faults.