### B Supplementary Material 2

#### B.1 Analytical Solutions for Direct Flux from

Power Cosine Sources

Direct flux originating from a source with flux distribution

Direct flux originating from a source with power cosine distribution

Direct flux originating from a source with power cosine distribution on a horizontal surface, i.e.,

E.g., for (i.e., a diffuse source)

Direct flux originating from a source with power cosine distribution on a vertical surface, i.e.,

E.g., for (i.e., a diffuse source)

or other exponents