Is it permissible to designate a portion of the solar energy donated to the mosque for one of its neighbors?

It is permissible to dedicate the solar energy system as an endowment for the mosque and one of its neighbors together, so that the benefit is shared between them, because endowing for two different entities is permissible. However, if the system is endowed for the mosque only, it is not permissible thereafter to allocate a part of it to the mosque's neighbor or to anyone else, because the endowment is a binding contract.