Boxborough and Littleton Solar

Program Training5/15/15

Arnie Epstein – “Solar Coach” Stow Solar Challengearnold.epstein@comcast.net

Solar in MLP versus IOU Communities

MLP’s versus IOU’s• Areas serviced by MLP’s can’t participate in Solarize Mass

• Unless your MLP opts in to the RET

• MLP’s policy for residential and commercial solar is different• From IOU’s

• IOU solar policy set by the state• IOU’s serve 85% of the state’s population

• From each other• Each MLP can set their own solar policy• Hudson Light & Power’s policy is different from Littleton Light

• Differences• Financial options – leasing and PPA’s may not be allowed• Credit for electricity fed back to the grid

• Net metering or other policy.• Hudson Light & Power doesn’t offer net metering

• Rebates and rebate requirements – if any

• Don’t anticipate “special” treatment for a community solar initiative• Participants in Stow Solar Challenge treated the same as any other solar installation by our

utility.

Solar PV Basics

Good Site

• A good site should be 80% of optimal or better• Optimal: 42 degrees tilt, 180 degrees azimuth, no shade from 9:00 AM to 3:00

PM

• Optimal about 1.2 kilowatt-hours per watt of solar per year.• A good site can have a wide variation from optimal

High tilt 91% of optimal: 65 degree tilt, optimal azimuth, no shadeWest facing 92% of optimal: 42 degrees tilt, 130 degrees azimuth, no shade

Solar PanelsStandard:• Canadian Solar 250 watt •IsoPhoton 250 watt (US Made)• 10/25 Year warranty• Standard Power Density: ~14.2 watts per ft2

• 17.75 kWh/ft2/year

High efficiency: • Sunpower 327/335/345 •US Company• 25/25 Year warranty• High Power Density: >18.6 watts per ft2

• 25.1 kWh/ft2/year

Roof Attachment

Inverters – Convert DC from Panels to AC

• String inverters• Convert the output of a number of panels• Typically mount near electrical panel• Cost somewhat less• Shade on one panel can impact performance of

all panels connected to the inverter• Shorter warranty – usually 10 years

• Microinverter• One per panel• Mounts on railing under panel• Shade on one panel will impact only

that panel. • Longer warranty – 25 years• More difficult to replace.

Snow on Panels

• Just leave it• Snow slides off panels

before rest of roof• Not usually a significant loss

of output – winter sun• Last winter was an

exception• Weight of snow and

panels• Concern when large

sheets slid of panels• Some residents had

snow cleared

Solar During Power Outage and Solar Storage

• During power outage, solar system will automatically disconnect• To insure no power on grid during repair

• Very few grid connected residential solar systems include storage• Expensive• No financial advantage if net metered

Common Adders

Financials and Incentives

Now is the Time to Install Solar• 30% federal tax credit expires at the end of 2016• Unlikely a new federal tax credit will be as generous

• SREC and net metering policy is likely to change• Net metering task force report submitted• Very unlikely existing installations will be impacted – “grandfathered”• For Littleton and Boxborough net metering policy determined by Littleton

Light.• But may be influenced by net metering policy at state level

• SREC policy determined at state level.

• Discounted pricing from community solar program• Lock in cost of electricity

Additional Financial Benefits of Solar

• $1,000 Mass tax credit• 20 year property tax exemption• Increased property value• Accelerated depreciation for commercial sites

SRECs

• Solar Renewable Energy Certificate• Electricity utilities in Massachusetts are required to secure a portion

of their electricity from solar generators.• An SREC represents the “solar” aspect of the electricity that was

produced NOT the electricity itself.• SRECs apply to all solar production, including electricity you use and

electricity sent to the grid. • SREC’s are sold to utilities so they can meet their solar requirement

SREC Value• SREC’s can be sold quarterly for a period of 10 years (40 quarters).• An SREC is 1,000kWh of solar generation. • A 5,000 Watt system = ~5-6 SRECs per year.• The value of the SREC is determined by the market.• The supply is determined by the number of solar installations.

producing SRECs in MA.• Utility SREC requirement increases each year (about 30%) following a

formula that takes into account previous year’s supply. • Currently working under SREC II • Somewhat lower price than initial SREC program (SREC I)• Value has continued to be strong – well over $200 per SREC

How do SRECs work?

• At contract you up with an SREC broker (aggregator).

• Install production meter.• Receive a check in the mail every 3 months,

for 10 years, for your solar generation.• First check is about 7 months after the system

goes live.

Net Metering

• Credits generated when system is producing more than is being used on-site• “Meter runs backwards”• Receive credits at full retail rate of

electricity.

Financials• A number of variables• Price of installation• Siting of solar panels• Price of electricity• Price of SRECs• Utility policy for electricity fed back to the grid• Tax credits• Terms of loan – if any

• Price of SRECs and electricity outside of installers control• Installer will not guarantee ROI• Many installers will guarantee minimum production

Example

Assumptions• 5 kW system• $3.50 per watt system

cost• Good siting• No loan• $200 SREC• Net metering• $0.11 kWh with 3%

annual increase

7 year payback

More Information• Sustainable Stow site• http://sustainablestow.org/stow-solar-challenge/

• Stow Solar Challenge facebook page• https://www.facebook.com/stowsolarchallenge

• Email• arnold.epstein@comcast.net