The building envelope, according to European and Italian regulations about energy efficiency, has to play the role of active element for energy production. The effectiveness for this kind of performance in territorial reconstruction, as the post earthquake in L’Aquila, is enhanced by the most adequate strategies for architectural integration at urban and building scale. Initiatives and proposals to allow from one hand to overcome the emergency state and from other hand to promote and start up an integrate development of territory to be rebuilt, request clear ad effective answers about “how to do”; at the same time is still open the debate about a strategic plan for retrofit, even more in historical context, where the values to be protected assume a primary relevance. A feasible way seems to be “active conservation” or “controlled transformation”, in order to achieve an equilibrate relationship between conservation of historical, architectural, environmental, materic and constructive values and the need for new requirements, through operative protocols for knowledge actions, in project information and pre-figuration system. The paper intend to identify, also through case studies, methods and criteria for evaluation and intervention strategies for architectural integration of solar systems, and in particular photovoltaic systems, in minor historical centres, according to assumptions of environmental, structural, morphological and constructive compatibility, in compliance with transformation levels suitable for historical heritage.