solar installations
BIPV Roof Overcomes Challenges By GIna r. JoHnson
A building-integrated thin-film PV (BIPV) system enabled a
Texas civic center to comply with ARRA and stay on budget.
CaM SOLaR
The Hopkins county civic center, with its 7,500 square feet of meeting space, a coliseum and livestock
pavilions, is an economic driver in the region. The 189-k W PV system is expected to save tens of thousands
of dollars per year in electricity bills.
The mission: to fit 187 kilowatts (k W) of photovoltaics (Pv) on a twice-reroofed, weight-limited structure, and to do it
within a million dollar budget. That was the
challenge dallas-based Horn brothers roofing
and its supplier, Sheffield metals International of
Sheffield village, ohio, faced in 2009 in responding to a request for proposals from the Hopkins
county civic center in Sulphur Springs, Texas.
most bidders focused on putting crystalline panels on the civic center’s upper roof. but Horn
brothers and Sheffield metals saw an opportunity to retrofit another roof area, over the facility’s stables, using a steel roof integrated with
laminated thin-film panels.
The dilemma arose from a stimulus funding
requirement that the system be installed on the
structure of the civic center, according to cr W
Associates’ Tom Glosup, a member of the civic
center board and the project’s construction
manager. In 2009, Hopkins county officials had
received American recovery and reinvestment
Act (ArRA) funding to make various upgrades,
including reroofing the civic center. Later, the
county applied for $827,000 in ArRA funding to
install a 187-k W Pv system to offset huge elec-
tric bills. That, plus $175,000 in rebates offered
by local utility oncor, gave the project an imme-
diate payback. Unfortunately, not knowing at
the time of the reroofing that solar might be a
possibility, the county had chosen a roof with a
10-year lifespan — far less than the typical 25- or
30-year Pv system life.
Pv System highlights
Hopkins County Civic Center,
Sulphur Springs, Texas
Site Details
average solar resource: 5. 33 kilowatt-
hours/square meter/day
average High/record Low Temps:
54°F–96°F ( 12°C- 36°C)/minus 4°F
(minus 20°C)
Latitude: 31.1 degrees north
System Details
General contractor: Horn Brothers
Roofing
system Designer, supplier: Sheffield
Metals International
systems Integrator: CAM Solar
array capacity: 189 kilowatts
annual ac Production: 292 megawatt-
hours
Panels: 77 68-watt (PVL- 68) and 1,386
136-watt (PVL-136) thin-film laminates
from Uni-Solar
Inverters: Two Solectria Renewables PVI
95 k W−480 VAC inverters
array: 63 strings of Uni-Solar PVL-136s
array combiners: Solectria STRCOM
21 circuit
system Installation: Thin-film laminates
on a retrofit standing-seam metal roof.
4.76° tilt, 180° azimuth
system Monitoring: Solectria SolrenView
Installation Time Frame: Three weeks in
January–February 2011
Cost and Incentives
bIPV system with uni-solar thin-film
laminates: $1.027 million
arra grant: ($827,000)
oncor utility rebates: ($175,000)
Total cost after incentives: $0
50 November/December 2011 SOLAR TODA Y solartoday.org
Gina R. Johnson ( editor@solartoday.org) is SOLAR
TODAY’s editor/associate publisher.
Devil is in the Details
To achieve the ArRA-funded 187-k W capacity, the project team had to fill the entire stable
roof with thin-film panels — more than 1,400 of
them. “Watts [generated] per square foot is less
on a thin-film amorphous [system], so we used
just about every square foot of roof area we had,”
said Watts. “We ended up with 189 k W.”
metal roof panels averaging 150 feet (50
