The 700-year-old parchment document from Edward II details privileges for the monks of Forde Abbey.
Volunteers who help run the store say the problem has started to affect trade.
RWE wants to install thousands of panels near Bradford Abbas to power up to 20,500 homes.
Police are investigating reports that a blue Transit-style van was seen close to the estate.
The gold and diamond ring, found in a Dorset field, sold at a auction for £50k including fees.
The gold and diamond ring was found in a farm field near Thorncombe in Dorset.
