Concentrating Solar Power (CSP) uses the solar radiation to produce electricity by means of a thermal cycle. This technology presents advantages over other renewables from the point of view of its integration into the grid and electricity markets. The reason lays mainly in its capabily of storing the received heat and producing electricity following a predetermined. This feature makes also possible its participation in reserve services, possibly increasing in this way the number of providers of this ancillary service. However, technical conditions and regulation makes this participation inefficient. In this paper, this assertion is developed and justified from estimates of the costs and benefits of this participation under the Spanish electricity market rules, as an example of the need of regulatory changes to exploit the possibilities of this new technology. (C) 2012 Elsevier Ltd. All rights reserved.