Study shows most US roofs can support a solar system
From Sandia National Laboratories.
Most U.S. rooftops in good repair can take the weight of solar photovoltaic (PV) systems. That’s the conclusion of a three-year study by a research team led by Sandia National Laboratories.
“There is a misperception in the
building industry that existing residential rooftops lack the strength to carry
the weight load of rooftop solar photovoltaic installations,” said Sandia
structural engineer Steve Dwyer. “Most existing well-built wooden rooftops can
support PV system loads.”
Sandia took on the job of
analyzing rooftop structural strength to address concerns raised in the U.S.
Department of Energy’s (DOE) Solar America Cities program. The agency named 25
cities to promote adoption of solar technology at a comprehensive, local level
through photovoltaics.
At least one city reported the primary barrier to solar was the difficulty and cost of obtaining construction permits for rooftop solar installations because of structural issues.
“I
couldn’t believe it was a problem,” said Dwyer, who led the Sandia test team.
“Solar PV systems represent little additional weight and roofs are very
strong.”
He said many code officials aren’t
familiar with solar technology and lack the training to evaluate how a solar PV
system might affect roof structure.
So they bring structural engineers into the
permitting process, adding time and money for the system owner and the solar
contractor.
Often, they then deny engineering certification for solar PV
installations on wood roofs, declaring the structures too weak.
Read more at Sandia Labs.