The 43 solar panels, installed in the kitchen garden, were meant to provide additional electricity to the sprawling Raj Bhavan here.
"The solar plates must have been stolen in the early hours of Saturday," East Khasi Hills police chief Mariahom Kharkrang told IANS.
"The thieves surely came with a big vehicle to carry out the heavy solar panel worth Rs.6.19 lakh."
The solar plates had been installed by Hyderabad Batteries Limited to generate 30 kilowatt power.
Meghalaya Governor R.S. Mooshahary had said the solar panels will cater to 50 percent of the Raj Bhavan requirements during peak season and about 80 pe cent during the lean season.
Meanwhile, police have questioned a number of people around the Raj Bhavan area and a manhunt is on nab the thieves.