Authors' model of choice uses endogenous marginal prices via 2SLS; the paper's central thesis is that average-price/OLS estimates are biased upward in absolute value, so the marginal-price 2SLS own-price electricity elasticities (obs 820=-0.38 and obs 821=-0.70) are the headline estimates || 'The effects on price elasticities of using (endogenous) marginal rather than (exogenous) average prices are estimated to be quite large.' (Abstract, p.86); 'In all cases, using exogenous average prices (and OLS as the estimation method) results in higher elasticity values (in absolute terms).' (p.101)
Denton, F. T., D. C. Mountain, and B. G. Spencer (2003): “Energy Demand with Declining Rate Schedules: An Econometric Model for the U.S. Commercial Sector.” Land Economics 79(1), 86-105