Regarding solar panel installed in my plot

i have a agricultural land in cuddalore half of it is sold and the rest could not be sold because it is  unapproved layout .one of the plot owners to whom i have sold the plot had installed solar panels in his plot as well as my plot which is unsold.I want to know if this is legal.he has installed without asking or informing me I came to know about  the matter from one of my relatives..what should i do regarding this.please inform.I cant go to the place as I am in chennai.