solar final presentation

Bates College Solar Initiative

Mac McReynolds, Matt Marcus, Jack Martell

Table of ContentsI. Contextual Framing and Project Goals

II. Power Purchase AgreementIII. Locations

A. Rooftop B. Off-Campus Site

IV. Savings Projections and Payback PeriodsV. Recommendations and Next Steps

Inspiration

- Environmental and Global Stewardship: A Goal of Bates College

- Climate Change

- Net Carbon Neutrality: Savings in Not Buying RECS

Bates College Context- Bates Current Use → ~ 12.741GWh/yr

in 2016

- Cost of Electricity → ~ $1.3 million/yr for campus loop

- Solar benefits- Clean energy- Economics- Leadership

Project Aims- Feasibility study of the

potential for a photovoltaic solar project for Bates College

- Zero net cost

- On and off campus

Power Purchase Agreement

On Campus Off Campus

Buy Back after 7 Years

Buy Back after 7 Years

No Buy Back No Buy Back

On Campus Power Purchase Agreement

BatesInvestor/InstallerOn Campus Solar Panels

$

30% Tax Break

$ for kW/hr Use

1. 2. 3.

Off Campus Power Purchase Agreement

Investor/Installer Off Campus Installation Grid

$

BatesNet Metering Credits

Net Metering Credits Equivalent

30% Tax Break

1. 2. 3.

4.

Installation Types1. On Campus Rooftop Project

2. Ground mount on campus or

neighboring property (direct

distribution line)

3. Ground mount off site (net metering)

On Campus Rooftop Criteria1. Rooftop oriented within 55

degrees east or west of true south (55 +/- 180°)

2. Adequate rooftop area

3. Lack of exterior shading

4. Electricity Demand Curve

Hourly Energy Load Curves

https://mysolarcity.com/Share/c5e1bfa0-19af-4bde-b597-2e51eac5cd4b#/monitoring/historical/day

*11/3/16

Bowdoin Hourly Solar Generation (kWh)Public vs. Residential Building

Hourly Energy Consumption (kW)

Buildings Suited for SolarMerrill Gymnasium Commons Gray Cage

Pettengill Hall 280 College Street Olin Arts Center

Monthly Variability in Production

On-Campus Capacity and Initial Costs

*Pending second assessment of Merrill Gym rooftop load capacity.

Building Orientation (degrees)

Estimated Pitch (degrees)

Estimated System Size

Estimated Annual Production

Estimated Annual CO2 Reduction (lbs/yr)

Estimated System and Installation Cost ($)*

Merrill Gym* 180 True 25 394 kW 480,564 kWh/year

363,090 922,534

Olin Arts Center 215 True 25 110 kW 134,167 kWh/year

101,370 257,400

Commons 215 True 20 65 kW 71,500 kWh/year 66,667 152,100

Gray Cage 125 and 215 True 25 225 kW 247,500 kWh/year

242,978 526,500

Pettengill Hall 125 and 215 True 25 130 kW 143,200 kWh/year

140,283 304,200

280 College St. 25 25 65 kW 68,500 kWh/year 63,774 152,100

Totals w/ Merrill Gym

n/a n/a 989 kW 1,145 MWh/year 978,162 2,314,834

Totals w/out Merrill Gym

n/a n/a 595 kW 664,867 kWh/year

615,072 1,392,300

Ground mount Location Criteria

1. Size- 3 acre minimum

a. No space on Bates College

2. Proximity to campusa. 1 mile for direct distribution lineb. 10 miles for social/academic utility

3. Current Land Statusa. Use, vegetative cover, pitch, structural

integrityCapped Landfills within 10 mile radius

of Bates College

Off Campus Location 1

LEWISTON MUNICIPAL LANDFILL

1. Property Size- 25 acres2. Distance from Bates College- 4.0

miles3. Ideal Land Status

Off Campus Location 2LISBON MUNICIPAL LANDFILL (NEW)

1. Property Size- 15 acres2. Distance from Bates College- 6.93

miles3. Ideal Land Status

On vs. Off Campus Conclusions

-Prioritize on campus installation to avoid net metering instability.

-On Campus allows for adherence to zero cost goal.

-Reconsider off campus installation once net metering future is determined.

PPA Payback OptionsOption 1: Discounted Purchase After Year 6

Benefits:

- Own system outright with potential for increased savings

- No longer purchasing kWh from solar investor

Risks:

- Potentially large investment to purchase panels (typically 40-60% of original price)

- Responsible for system maintenance following purchase

- Solar production fluctuations

Option 2: PPA Extension (up to 30 years)

Benefits:

- No responsibility for system maintenance

- Fixed photovoltaic electricity rate for extent of PPA

- Decreased demand charge, fewer kWh purchased from the grid

Risks:

- Lower long-term savings

- Solar production fluctuations

Solar Savings Equation without Buyout-Guaranteed savings originate from fewer kWh purchased from grid and lower demand charge

● Total cost: (supply $/kWh)(kWhT) + ($ delivery service/kwh)(kWhT) + ($ demand/kW)(kWT)

● Total cost with solar: (supply $/kWh)(kWhT) + ($ delivery service/kwh)(kWhGrid) + ($ demand/kW)(lower kWGRID)

● Total cost - New total cost w/ solar = Savings

Savings without Purchasing Array– Demand Charge Unchanged

Key Information

- Solar installations on: Gray Cage, Olin Arts Center, Dining Commons, Pettengill Hall, 280 Campus Ave.

-Savings from decrease in kWh purchased from the grid

● Savings without Merrill:○ $3,951.63/year○ $98,790.75 over 25 years

● Savings with Merrill:○ $7,273.29/year○ $181,832.30 over 25 years

Savings without Purchasing Array– Demand Charge Changed

Key Information

- Solar installations on: Gray Cage, Olin Arts Center, Dining Commons, Pettengill Hall, 280 Campus Ave.

-Savings from decrease in kWh purchased from the grid

- Assumes solar array produces–on average–25% of energy potential during times of monthly peak demand


● Savings with Merrill:○ $44,691.37/year○ $1,018,494 over 25 years

Savings without Solar Purchase

Savings with Solar Purchase

Annual Savings 25 Year Savings

Identical Demand Charge

Without Merrill $3,951.63 $98,790.75

With Merrill $7,273.29 $181,832.30

Decreased Demand Charge

Without Merrill $26,665.63 $666,640.80

With Merrill $44,691.37 $1,018,494

Solar Savings with Buyout in Year 7● Savings originate from:

○ Savings every year from decreased demand charge and decrease in kWh from grid○ After year six, no longer paying for kWh previously purchased from solar investor

● Savings function:

[($ solar array installation)(fraction of installation $ for buyout) + (maintenance costs/year)(x years)] - [(supply $/kWh)(kWh used from solar/year)(x years) + (savings without buyout/year)(x years)] = 0

Savings from Solar Purchase– Low Fixed CostKey Information

- Assumes solar produces 25% of energy potential during time of peak demand

- Assumes annual maintenance cost of 0.5% of installation cost

● Without Merrill:○ $556,920 fixed cost

● With Merrill:○ $925,933.60 fixed cost

● Savings without Merrill:○ $66,244.80/year○ $1,099,201 over 25 years


Savings from Solar Purchase– High Fixed CostKey Information

- Assumes solar produces 25% of energy potential during time of peak demand

- Maintenance cost of 0.5% of installation cost

● Without Merrill:○ $835,380 fixed cost

● With Merrill:○ $1,388,900.40 fixed cost





Annual Savings 25 Year Savings

Low Fixed Cost Without Merrill $66,244.80 $1,099,201

With Merrill $109,315.50 $1,766,216

High Fixed Cost Without Merrill $66,244.80 $820,740.50

With Merrill $109,315.50 $1,343,989

Off Campus Savings: Calculations and Scenarios

● 500 kW system○ $2.15/Watt→ $1,075,000 upfront cost

■ Maintenance cost→ .5% of initial cost○ High-Expected-Low kWH production

● Purchase at Year 7 or Not○ Buyback Cost-40%-60%

● Annual Lease Cost-$20,000/MW

1. Solar Buyback after 7 Years

60% Buyback 40% Buyback

High kWh Production

Expected kWh Production

Low kWh Production

2. No Solar Buyback

High kWh Production

Expected kWh Production

Low kWh Production

Low Productivity-High Buyback Cost Scenario● Annual Generation: 617,173 kWh

● Annual Savings: $30,003

● 60% Buyback Cost: $645,000

● Buyback Period: 21.5 years

● Net Savings: $355,083.50

High Productivity-Low Buyback Cost Scenario● Annual Generation: 662,334 kWh

● Annual Savings: $33,164

● 40% Buyback Cost: $430,000

● Buyback Period: 12.97 years

● Net Savings: $639,115.25

Expected Productivity- No Buyback Scenario● Annual Generation: 644,230 kWh

● Total Solar Savings: $12,884.6● -Annual Lease Cost: $10,000● Actual Savings=2,884.6

● $.13/kWh Net Metering Credit Rate vs. Currently Paid $.11/kWh Rate

● Net Savings: $72,115

System Purchase vs PPA Extension Conclusions- Extended PPA (25 Years)

- Stability on returns- No high fixed cost- No maintenance responsibility

Conclusions and Next Steps1. Extended Power Purchase Agreement2. Prioritize on-campus installation

a. Projected annual/lifetime savingsb. Net Metering

3. Future large off-campus project

Next Steps:1. Secondary Merrill assessment2. Work with Office of Advancement to

facilitate bidding process3. Legal counsel

solar final presentation

Documents