PRINCETON, W.Va. -- Princeton will use solar power to keep its new welcome signs lit at night.Solar panels will charge during the day and provide power for the signs' lights at night.Three large signs and four smaller signs are being installed at entryways to the city. Architect Todd Boggess with E.T. Boggess Architects tells the Bluefield Daily Telegraph that the project is expected to be completed within 30 days.The signs will display Princeton's new slogan, "The Heart of Mercer County."City officials held a contest in 2011 to replace the previous slogan, "The Gateway to Four Seasons Country." The winning slogan was chosen from nearly 600 entries.