Solar Building, Commercial building in Albuquerque, New Mexico.

The Solar Building is a one-story International Style office building of two sections. Its north wing has an irregular quadrilateral cross-section, with the roof angled at 20 degrees and the south wall at 30 degrees to hold the solar collectors; seven steel bents spaced 18 feet apart frame it. The flat-roofed south wing, partly faced in brick, was extended in 1962, and the main entrance sits where the wings meet.

Bridgers & Paxton, founded in 1951 by Frank Bridgers and Donald Paxton, built the Solar Building between March and August 1956 to house their engineering firm, with Stanley & Wright as architects. The solar collector was abandoned during a 1962 expansion, then restored in 1974 by Penn State researcher Stanley Gilman under a National Science Foundation grant. The firm moved out in 1985, the year the building joined the New Mexico State Register of Cultural Properties; it entered the National Register of Historic Places in 1989, aged 33.

The building's name comes from its 56 custom aluminum solar thermal collectors, coated in black paint and covered with glass, mounted on a south wall angled 30 degrees. Bridgers & Paxton ran their engineering firm here, and the design inspired later active solar heating systems. Articles in Life and Popular Mechanics brought visitors and readers to the address.

The building stands at 213 Truman Street NE in Albuquerque, near the intersection with Copper Avenue. The angled south wall holding the collectors faces the street and can be viewed from outside; the windowless brick east elevation faces the other street. The interior is a working office and not open for tours.

The collectors were custom-fabricated aluminium panels coated with low-reflectivity black paint under glass, feeding a 6,000-gallon insulated underground tank that held enough hot water for three days of cloudy weather. The system cost about $15,000, roughly twice a conventional one, and kept working through January 1957, a month with only three sunny days.