The Thoreau Farm Trust, a nonprofit organization, is launching a fund-raising effort to install a solar photovoltaic system at the birthplace of 19th-century author and philosopher Henry David Thoreau. The trust’s goal is to raise $25,000 by the end of this month, in order to get the system installed before the ground freezes for the winter, according to its announcement on the campaign. A supporter has promised to match all donations up to $12,000. The Thoreau Farm property, at 341 Virginia Road, is listed on the National Register of Historic Places, and the trust said that taking the house off the electrical grid would be in line with Thoreau’s environmental values, and demonstrate to visitors how to be more environmentally conscious. For more information or to contribute to the project, visit www.thoreaufarm.org. Full story for BostonGlobe.com subscribers.