Is bigger always better? Designing economically feasible ocean thermal energy conversion systems using spatiotemporal resource data

•We studied ocean thermal energy conversion’s economics under off-design conditions.•Our design model works for any system size, location, and temperature profile.•In most analysed cases, conservatively designed systems yield the lowest cost.•The electricity cost of a 136 MWgross plant are as low as 15.12 US¢(2021)/kWh.•We give technical and regulatory recommendations to reduce investment costs further.