Utility Scale Rooftop Solar Ability of neighborhood solar
to defer new electrical facilities
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• Describe Rocky Mountain Power’s in-depth study of neighborhood solar to offset the need to build new infrastructure (power plants, substations and lines)
• Outline Rocky Mountain Power’s progress on Utah carbon reduction goal
• Describe Rocky Mountain Power’s support of customer-owned renewable energy
Purpose of presentation
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Customer use on the rise• Rocky Mountain Power residential
customers use about 26% more electricity than 20 years ago
• To meet our obligation to serve, additional power supply resources, substations and power lines are needed to meet growing customer use
• New facilities are expensive and difficult to permit
• Advocates want different solutions
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Can rooftop solar defer new facilities?
Study Area Boundary
• Customers questioned substation expansion in an established neighborhood
• Public opposition delayed conditional use permit
• Undertook subsequent study of rooftop solar to determine its ability to meet customer use
SOUTH TEMPLE
UN
IVER
SITY
STR
EET
1100
EAS
T
400 SOUTH
900
EAST
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Scope of the solar opportunity
Category Type of BuildingMedian Roof
FootprintMedian # of
PV PanelsMinimum # of
PV PanelsMaximum # of PV Panels
Average Usable Roof Area
Residential Single Family Residential 171 m2 25 0 119 13.81%
Multi-Residential Apartments, Condos, etc. 173 m2 32 0 397 19.88%
Sm. Commercial Restaurant, Commercial Retail 349 m2 136 6 340 31.31%
Lg. Commercial Offices, Hospitals, Churches 430 m2 160 16 917 32.74%
Unknown Unknown Land Use 196 m2 26 2 262 14.57%
20 ft.
40 ft.
60 ft.
80 ft.
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Determining panel location
176 Panels97.79kWh/day19.8% usable roof
9:30am 12:30pm 6:30pm
• Evaluated roof shading on every structure• Determined solar exposure • Locate solar panels where they produce the most energy
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• Two-thirds of rooftops are suitable for solar panels (237 of 356 ) • Total number of panels 13,304 • Study uses high efficiency panels; solar energy to electricity = 19%
Study aims to maximize solar output
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CustomerUse
SolarProduction
Here comes the sun
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Here comes the sun
CustomerUse
SolarProduction
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Here comes the sun
CustomerUse
SolarProduction
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Here comes the sun
CustomerUse
SolarProduction
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Here comes the sun
CustomerUse
SolarProduction
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Here comes the sun
CustomerUse
SolarProduction
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Here comes the sun
CustomerUse
SolarProduction
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Here comes the sun
CustomerUse
SolarProduction
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Here comes the sun
CustomerUse
SolarProduction
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Here comes the sun
CustomerUse
SolarProduction
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Here comes the sun
CustomerUse
SolarProduction
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Here comes the sun
CustomerUse
SolarProduction
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Estimated solar production Solar Energy Conversion:
2,210 MWh annual energy production• 1,560 MWh during summer months (May-Sept.)
Maximum Solar Power Output – as calculated June 21 = 1.52 MW (summer solstice)• Temperature Corrected = 1.45 MW at 76o F
Solar Output on Circuit Peak August 2 = 0.54 MW (2010 circuit peak)
• Temperature Corrected = 0.48 MW at 93o F
Projected 2011 Circuit Peak = 4.6 MVA
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6:00 am 9:00 am Noon 3:00 pm 6:00 pm 9:00 pm0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
Study areaAugust 2, 2010
Customer Use Solar Production
Meg
awatt
s
Solar contribution to peak
Solar output at ideal conditions
Actual customer load
Circuit Peak
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