We develop a theoretical model for firms' consumption of electricity, under fixed-rate and time-variant pricing regimes. Our model is sufficiently flexible to account for heterogeneity in key parameters across and within both geographic space and sectors. We use recover estimates for key parameters using an instrumental variables regression, then estimate the underlying heterogeneity across firms using maximum likelihood estimation. We find evidence that commercial firms respond differently than industrial firms to time-variant pricing, and provide recommendations for future research to expand on these findings.