More than 60 ground-based solar panels have been stolen from a field in the village dubbed “Solar St James”.
Some 66 panels and associated equipment in a field near White Cross, Sutton St James, were taken between 5pm on Saturday and 7.30am on Monday.
Police are also investigating a similar incident in Brant Broughton, near Lincoln, and are warning farmers to step up security.
A police spokesman said: “The thieves appear to be targeting isolated locations and owners of such PV arrays are advised to take all possible precautions.
“Keep gates securely locked to limit vehicular access to fields, check your sites regularly and consider other options such as security lighting and CCTV.
“Contact your local crime reduction officer by calling 101 for specialist advice.”