in cases page where re would be driven by the c price alone and re incentives were to persist the additional support only creates windfall profits it depends on the cost of the promoted re sources and on the amount of c they avoid and on the cost of avoiding same quantities through other measures that would have been mobilised had renewables not been promoted electricity generation from renewables is particularly challenging it requires an assessment of the c content of the kwh they displace which depends on the merit order ie the last production capacity required to fulfil the demand at every moment