Solar installations in historic districts typically must go through an additional step in the permitting process to ensure the location and method of installation comply with local historic requirements. In some jurisdictions, this review is done within the standard permit review process. In others, it is handled by a separate historic review board. Your installer will be familiar with the requirements in your area. You should expect your installer to work with the relevant review body to secure the necessary permits. The cost for doing so should be included in the cost of going solar.