Southern California Edison s Preferred Resources Pilot (PRP) Solar Siting Survey Summary Document Introduction The Southern California Edison (SCE) Preferred Resources Pilot (PRP) Solar Siting Survey, completed by the Clean Coalition on behalf of SCE, provides an estimate of the technical solar PV generation potential in the PRP area for specific sites that can generate 500 kw (AC) of power or greater. This Solar Siting Survey is based on the following conservative methodology: Identifying appropriate sites, in both size and position, including rooftops, parking lots, and parking garages Narrowing down the candidate sites to the most feasible locations, using estimates that exclude difficult, highly cluttered, or overly shaded areas Measuring the most feasible rooftop square footage per candidate site Calculating the solar potential in kw AC per site Including logical groupings where applicable such as office parks and shopping centers The deliverables for this survey include this summary document, an overview in power point format, the excel file that provides the detailed survey data per site and in summary, and a map file (.kml) that, when used in Google Earth, displays the PRP area with all the surveyed sites. The map indicates each surveyed site with a sun icon and a number representing the total potential PV for that site. Clicking on the sun icon will provide additional details including the site address, the solar density rating for that site, and the distance to the closest feeder or feeders. For aggregated sites such as shopping centers or business parks, the map also provides the total solar PV potential for that aggregate Highlights Based on the above criteria, the Clean Coalition identified over 160 MW of new solar PV potential in the PRP area. The technical solar potential may be closer to 300 MW for including sites in the 100kW 400kW range, which is based on past experience and an educated assessment of the PRP grid area 1. The two tables below provide additional summary details. The tables (as well as the excel summaries) break down the totals into various categories, including 1 The Clean Coalition's experience is supported by studies in the LADWP service territory where 50-500kW siting opportunities had a total capacity of about 3x more than the 500kW+ siting opportunities.
each PRP area (24, 59) with 22 sites identified as overlap sites that exist where areas 24 and 59 overlap according to the map data provided by SCE. Table 1 below provides the summary by size of PV output: the totals per sites greater than 1 MW, sites greater then 500 kw but less than 1 MW, and sites less than 500 kw. The sites that are less than 500 kw are included as part of logical groupings such as office parks or shopping centers 2. Table 1. PRP Solar Potential by PV size Table 2 below provides the summary broken down by site type: the totals for rooftops, parking garages (multi-story parking structures that would enable full cover canopy mounting), and parking lots (excluding aisles), and including one brown field. Table 2. PRP Solar Potential by Site Type The Summary page in the excel spreadsheet also includes a breakdown by city and zip code. Observations: 1. More opportunities are available from structures less than 1 MW vs. greater than 1 MW due to common commercial and industrial building sizes. 2. Parking lots and parking garages represent a potential that is about 75% of the rooftop potential. Most of the large commercial buildings have adjoining large parking lots, and solar PV in parking lots provides an additional benefit: shade for cars (PV covered parking lots at schools and colleges are often the first to be occupied). 2 The grouped siting opportunities in the Solar Siting Survey are those that appeared to be within a single property AND that would aggregate to at least 500kW.
The following sections provide additional details regarding the inputs, assumptions, and methodologies used to derive the results. Methodology including Inputs, Assumptions and Outputs Methodology summary: 1) Define realistic solar potential per site category. Tool/Source: local PV project developers. Rooftops, Parking Lots, Parking Garages High, Medium, Low PV density assessment based on contiguous space / amount of clutter per site 2) Identify, categorize and quantify PV potential for sites. Tool/Source: Google Earth Pro, Google Maps. Site sq. ft. and density assessment Location Distance to closest feeder(s) 3) Survey full PRP Area. Tool/Source: Google Earth Pro, Google Maps, Web searches. Identify target zones Identify largest opportunities: 1MW+ Rescan for smaller size sites: 500 kw+ Rescan for groupings: business parks, shopping centers, etc. 4) Generate.kmz and.xlsx files. Tool/Source: Google Earth Pro, MS Excel 5) Generate summary reports. Tool/Source: MS Word, PowerPoint Inputs and Assumptions: SCE provided the following as input to the PRP PV Potential Survey: Preferred Resources Pilot Map (.kmz) for PRP areas 24 and 59. NOTE: A version with transparency for the defined PRP areas was created to allow potential PV structures to be visible through the PRP area color. PRP RFO Interconnection Map (.kmz): substations, feeders. NOTE: The feeder information was extracted to find the amount of available capacity on each feeder which is included in the excel spreadsheet. The Clean Coalition reviewed existing large commercial installations to establish typical PV layout and density figures for the area. In addition, the Clean Coalition consulted with solar project developers who deploy projects in the PRP area. Their expertise provided an accurate, conservative estimate of watts per square foot as a calculation used to derive the PV potential per site. With current and pending PV panel efficiencies, the Clean Coalition rated each viable site as high, medium, or low density. The density in this case pertains to the density of solar panels
each site supports high density sites have more contiguous open space with fewer obstructions such as skylights; lower density sites have more obstructions. The survey calculates solar PV potential based on DC power levels of 8 Watts/sq. ft. for high density sites, 7 Watts/sq. ft. for medium density sties, and 6 Watts/sq. ft. for lower density sites. For AC output, these numbers were reduced to 7-6-5 Watts/sq. ft. respectively. These numbers are probably more conservative than needed, especially for the medium and low density scenarios, but they provide additional downward margin to allow for increasing roof clutter typically found in older buildings with lower density but still usable PV potential. The table below summarizes this Watts/sq. feet methodology used in the survey. Structure High Density Medium Density Low Density Notes Flat Roof 7 W/Sq. ft. 6 W/Sq. ft 5 W/Sq. ft 1, 2 Parking Garage 7 W/Sq. ft N/A N/A 1, 2, 3 Parking Lot N/A 6 W/Sq. ft N/A 2, 4, 5 Brown Field 7 W/Sq. ft N/A N/A 6 Table of power densities for different structures in Watts AC/sq. ft. Table notes: 1. Area calculated is normally corner-to-corner unless otherwise noted in the comments field in the spreadsheet. Edge clearance setbacks and panel maintenance access are assumed in these numbers. 2. May have areas restricted, notched or cut off as noted in the comments field in the spreadsheet. 3. High density due to no need for fire truck access between parking rows 4. Only includes central areas that have double row (nose-to-nose) parking. Single row parking around perimeter omitted. Impact on trees & planter boxes not included. 5. Medium density due to requirement for fire truck access clearance between parking rows. 6. Brown field was initially considered but dropped after project started. One potential site was left in database for reference. The survey identified individual sites and groupings of sites for solar PV opportunities in the PRP area. Google Earth and Google Maps were used to scan systematically the large rooftops, parking lot, and parking garage opportunities. These tend to cluster in commercial and industrial pockets due to zoning laws. After representative reference sites were examined, logged and turned into a map file (.kml display file), the process was repeated over the entire area, also using searchable databases to identify typical candidate locations. These locations include industrial parks, business centers, shopping centers, movie theater complexes, big box stores (Costco, Walmart, Target, Lowes, The Home Depot, Staples), educational locations (schools, colleges and universities), event centers, and public structures (e.g. airports). Only flat, horizontal surfaces were considered for this study. Angled rooftops require detailed analysis that is beyond the scope of this study. Structures with significant shade sources on East,
South or West sides were excluded due to lowered potential energy production. In some cases, only portions of a structure were excluded due to shading, noted in the comments field in the excel spreadsheet. Sets of buildings that could generate over 500 kw in aggregate were excluded if a common grouping relationship or ownership was not immediately obvious. Each identified potential site was measured for PV-viable rooftop square feet. The square feet amount was then multiplied by the correct Watts/sq. feet amount as outlined above. Each site was also measured in terms of distance to the closest feeder or feeders. Outputs: The detailed results were tabulated in the excel spreadsheet that accompanies this Summary document. The Excel file includes: Detailed data per site, including site address, site type, density rating, viable square feet, PV potential per site, distance to feeder(s), available feeder capacity, notes, etc. Summary tab: contains all summaries and breakdowns All data fields are explained within the file, and the data can easily be filtered by city, zip code, type of structure, etc. A map file (.kml) was also produced using the data from the spreadsheet. The map file enables the sites to appear in Google Earth, using the iconography listed below.
Type of Site Placemark Icons Comments Potential PV site Includes rooftops, parking lots, parking structures, and brown field. The solar potential in kw AC is shown in the title. Clicking on the sun icon provides Shopping Center more info. Business Center Education Airport Informational site Examples of structures with existing PV, including PV sites already in place within a group. PRP PV Potential Survey Google Earth map file iconography In the map, clicking on the Sun icon located at each surveyed site provides additional details for that site. This information includes: kw potential for each site, including a note about grouping if icon represents a group; site identifier (if known), including name, occupant, assessor parcel number, etc.; address (note: the same address is used for all items in a grouping such as a shopping or business center); roof area in square feet (for individual sites); structure type (e.g. rooftop, parking lot); PV density rating, or assessment; PRP area(s) in which structure is found; distance to closest feeder(s); and any relevant notes. Thus, using the map file, one can easily find all the potential sites and the relevant information per site. The picture below shows a portion of the PV Potential map with one of the locations (sun icons) selected to show the info panel.
Section of PRP Solar Siting Survey Map showing Info Panel for a single site These documents and the analysis and conclusions contained in them are exclusively the work of Clean Coalition, who bears sole responsibility for the content.