mapping rooftop solar power potential in greater cincinnati brandon flessner gis analyst oki...
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Mapping Rooftop Solar Power Potentialin Greater Cincinnati
Brandon Flessner
GIS Analyst
OKI Regional Council of Governments
2015 Ohio GIS ConferenceSeptember 21 - 23, 2015 | Hyatt Regency Columbus| Columbus, Ohio
Solar Ready Grant
Data
Building FootprintsProvided by counties, Open Street Map~700k polygons
LiDARProvided by OSIP, KYFromAbove, IndianaMap~9.8 billion points
Digital Surface Model (DSM)
Area Solar Radiation
Demo Analysis
Identify Roof Planes
Overlay Usable Areas
“Usable” Roof Aspects “Usable” Solar Radiation
“Usable” Roof Area
System Size
Left Building Example:• 92 cells (6.25 ft2 / cell) = 575 ft2 of usable roof area• Residential solar panel 40” X 66” or 18.3 ft2 (0.25 kW)• About 31.4 panels would fit in usable area• System Size = 7.86 kW
Adjustment by roof typeFlat roofs:• Slope less than 22 degrees• Usable area = usable solar radiation• System size down rated for OSHA requirements, extra mounting hardware,
spacing• Aspect and slope are constants (180, 10)
Simple roofs• Less than 6 roof planes• Usable area = overlay of usable solar radiation and usable roof planes• Aspect and Slope = average value of largest roof plane
Complex roofs• 6 or more roof planes• Usable area = overlay of usable solar radiation and single largest roof plane• Aspect and Slope = average value of largest roof plane
Annual Power Generation• Incorporate Typical Meteorological Year data for Lunken Airport,
Cincinnati, via PVWatts• Build dataset of typical values for system size, aspect, slope and
annual output.• Calculate equation via multiple linear regression • Apply equation
Annual output (kWh) = -544.27+1148.0277 * System Size - 0.1515 * Aspect + 15.2126 * Slope
Economics• Annual Savings
• Annual output (kWh) * retail price of electricity ($/kWh)• Ohio = 9.16 cents / kWh
• Installation costs• $3.30 per installed watt• 4 kW system would cost about $13,200
Other Considerations• Python• Accuracy• Time• Website
