Version 1.8 of the award-winning ENERGY10[TM] software provides building designers with an easy-to-use tool to help them integrate photovoltaics and solar domestic hot water into energy-efficient buildings. New features include a photovoltaic module that allows users to model and simulate the performance of a PV system that is either standalone or integrated with the building and a solar domestic hot water module that provides a new solar domestic/service hot water modeling capability.