This paper uses a theoretical partial equilibrium model to analyse the integration of intermittent renewable energy technologies such as solar or wind into an electricity mix comprising of conventional energy technologies. We consider the intermittent nature of renewable energy resources as important for capacity investment and propose that wholesale electricity prices be contingent on the availability of the resource and passed to consumers through state-contingent retail contracts. The novelty of the paper lies in the redefinition of the role of retailers who are able to propose diversified electricity supply and price lists that allow consumers to choose  their optimal electricity consumption based on their flexibility. By considering a competitive environment whereby consumers are utility maximizers and producers and retailers maximize profits, we find efficient partial equilibrium in a contingent electricity market. We determine the optimal level of renewable energy capacity (and investment) and  ultimately, characterize the conditions under which modifying electricity supply of the contracts increases investment in renewable energy capacity.