The historic house in Concord where author Henry David Thoreau was born is collaborating with Solect Energy of Hopkinton to install a seven-kilowatt solar energy system. The solar energy firm will install the system for free and will donate the power it produces to Thoreau Farm, also at no charge. “Our partnership with Solect brings an innovative, sustainable approach to supplying electricity to Thoreau Farm,” said Ken Lizotte, president of the house’s board of directors. “Our renovations over the past several years have attempted to capture Thoreau’s ideals and apply them to the 21st century. We believe solar fits into the simple, yet contemporary approach we are trying to bring to the house.’’ Thoreau Farm’s move toward solar began a decade ago when plans were first implemented to rehabilitate and renovate the 18th-century farmhouse where the Transcendentalist was born 199 years ago. The solar panels will be mounted on the ground, not on the building itself, to preserve the historic appearance of the house.