solar energy 101 handbook - singing river electric...

Solar 101 Handbook | 1


This handbook is a supplement to the Touchstone Energy Cooperatives’ Solar 101 online course. If you’re interested in learning about anything in this handbook, would like to take the course, or have other questions, please contact Touchstone Energy at [email protected].

Disclaimer The Handbook is intended to be a general resource for Touchstone Energy cooperatives and their member-owners. The Handbook is not an exhaustive and complete examination of every issue associated with solar energy. The Handbook is not tailored to specific circumstances that may apply. Touchstone Energy and NRECA are not attempting to render specific professional advice in this Handbook. Touchstone Energy and NRECA encourage you to consult with qualified persons about your specific circumstances. Touchstone Energy and NRECA are not endorsing any particular design or practice featured in these materials and are not suggesting they are appropriate for every circumstance. Each member should use its independent judgment and discretion to make its own business decisions on whether and how to use the Handbook and in determining whether to develop and implement solar energy. Disclaimer of Warranties & Liability: THIS GUIDE IS PROVIDED “AS IS” AND TOUCHSTONE ENERGY AND NRECA MAKE NO WARRANTIES OR REPRESENTATIONS, EITHER EXPRESS OR IMPLIED, ABOUT THE INFORMATION CONTAINED IN THE GUIDE, INCLUDING WARRANTIES OF ACCURACY, COMPLETENESS OR USEFULNESS. The Handbook contains findings that are general in nature. Readers are reminded to perform due diligence in applying these findings to their specific needs, as it is not possible for Touchstone Energy or NRECA or its contributors to have sufficient understanding of any specific situation to ensure applicability of the findings in all cases. The information in Handbook is not intended to develop, and does not develop, best practices, recommendations, duties of care, standards, or similar items, whether direct, indirect, express, implied, de facto, or otherwise. Similarly, the information in the Handbook does not intend to create, expand, or otherwise impact, and does not create, expand, or otherwise impact, an electric cooperative’s or its member-owners’ legal duties, obligations, expectations, or liabilities. Touchstone Energy and NRECA do not assume liability for how readers may use, interpret, or apply the information, analysis, and guidance herein or with respect to the use of, or damages resulting from the use of, any information, method, or process contained herein. In addition, Touchstone Energy and NRECA make no warranty or representation that the use of these contents does not infringe on privately held rights.

mailto:[email protected]


Using this Handbook Use the resources included in this handbook to help answer members’ questions, direct them to additional resources, and review what you learned in the Solar Energy 101 course. Add your own notes, additional Websites, and other resources as you find them.

4-14 Solar 101 Glossary

15-18 Solar Energy Frequently Asked Questions

19-23 Is Solar Right for Me?

24-26 10 Steps to Take Before Installing Solar Energy

27-29 Solar Ownership Options

30-32 Solar Systems: What Size is Right for You?

33-35 Community Solar: An Easy Option

36-39 Questions to Ask a Solar Contractor

40-54 Sample Proposal: Things to Consider

55-56 Additional Resources

57-58 My Notes

Table of Contents


Solar 101 Glossary Terms Commonly Used in the Photovoltaic Industry. After taking the Solar 101 course, you’ll have a better understanding of many of these concepts and terms.

-A- Absorbers - Dark-colored objects that soak up heat in thermal solar collectors.

Active solar heater - A solar water or space-heating system that moves heated air or water using pumps or fans.

Alternating current (AC) - Electric current in which the direction of flow is reversed at frequent intervals--usually 120 times per second (60 cycles per second or 60 Hz). This is the type of current delivered by the cooperative to the member.

Amorphous semiconductor - A non-crystalline semiconductor material. Easier and cheaper to make than crystalline, but less efficient and slowly degrades over time. Also called thin film.

Ampere (A) or amp - The unit of measurement for the electric current; the flow of electrons. Also indicates the size of circuit breakers and fuses. One amp is produced by an electric force of 1 volt acting across a resistance of 1 ohm. For example, a 1,200-watt, 120-volt hair dryer pulls 10 amperes of electric current (amps = watts/volts).

Angle of incidence - Angle between the surface and the direction of incident radiation; applies to the aperture plane of a solar collector. Most modern solar panels have only minor reductions in power output within plus/minus 15 degrees. The loss is a function of the cosine of the angle of incidence, so if sunlight strikes the surface of the collector at a 45-degree angle, output drops off by about 30%. (1 – cosine (45 degrees) = 0.29)

Annual solar savings - The annual solar savings of a building is the energy savings attributable to a solar feature on a building relative to the energy requirements of the same building without solar.

Average demand - The amount of electricity drawn from an electric system over a period of time, measured in kilowatts. For example, the number of kilowatt-hours used in a 24-hour period, divided by 24 hours, tells the average demand for that location in that time.

Avoided cost - A calculation that estimates the expense an electric utility incurs to supply or generate a certain amount of power. In practice, it refers to the price that qualifying facilities under the Public Utility Regulatory Policies Act of 1978 are entitled to receive for excess power sold to a utility. Avoided cost is established at the price a utility would have paid for power had it not purchased from a qualifying facility.


Antireflection coating - A thin coating of a material, which reduces the light reflection and increases light transmission, applied to a photovoltaic cell surface.

Array - Any number of photovoltaic modules connected together to provide a single electrical output. Arrays are often designed to produce significant amounts of electricity.

Autonomous system - A stand-alone PV system that has no back-up generating source. May or may not include storage batteries. Most battery systems are designed for a certain minimum "days of autonomy," which means that the batteries can supply sufficient power with no sunlight to charge the batteries. This varies from three to five days in the sunbelt, to five to ten days elsewhere.

Azimuth - Angle between the north direction and the direction the house or solar array faces; measured clockwise from north. As applied to the PV array, 180-degree azimuth means the array faces due south. 90-degree azimuth means the array faces east.

-B- Balance of system (BOS) - Represents all components and costs other than the PV modules. It includes design costs, land, site preparation, system installation, support structures, power conditioning, operation and maintenance costs, batteries, indirect storage, and related costs.

Battery - Batteries are sometimes sold with a solar electric system. The primary purpose is to store the electricity not immediately used, which could be used at some later time or during a grid outage.

British Thermal Unit (BTU) - The amount of heat energy required to raise the temperature of one pound of water from 60 degrees F to 61 degrees F at one atmosphere pressure. A pint of water weighs roughly one pound. It takes 140 BTUs to heat tap water from 60 degrees F to 200 degrees F for a cup of coffee

-C- Capacity factor - The ratio of actual net electrical energy generation to the maximum possible energy that could have been generated if a plant operated at its maximum capacity rating over the same time. Capacity factor is normally reported as a percentage.

Cell - The basic unit of a photovoltaic panel.

Cell junction - The area of immediate contact between two layers (positive and negative) of a photovoltaic cell. The junction lies at the center of the cell barrier or depletion zone.


Circuit - See Electric circuit.

Conversion efficiency (cell or module) - The ratio of the electric energy produced by a photovoltaic device to the energy from sunlight striking the cell. Tests are based on a solar intensity of “one sun” – the irradiance of the sun on Earth’s outer atmosphere equal to 1 kW/square meter.

Crystalline silicon - A type of photovoltaic cell made from a slice of single-crystal silicon or polycrystalline silicon.

Customer load - The amount of power your site uses. Load may be expressed in kilowatts (capacity) or kilowatt-hours (energy use). A site's peak kilowatts generally refers to when electric demand requirements are highest.

-D- Demand - The level at which electricity is delivered to end-users over a given period of time. Electric demand is measured in kilowatts.

Diffuse insolation - Sunlight received indirectly as a result of scattering due to clouds, fog, haze, dust, or other obstructions in the atmosphere. Opposite of direct insolation.

Direct current (DC) - Electric current in which electrons flow in one direction only. Opposite of alternating current. Batteries and PV cells deliver DC current.

Direct insolation - Sunlight falling directly upon a collector. Opposite of diffuse insolation.

Distributed systems - Systems that are installed at or near the location where the electricity is used, as opposed to central systems that supply electricity to grids. A photovoltaic system installed at a home is a distributed system.

-E- Electric circuit - Path followed by electrons from a power source (generator or battery) through an external line (including devices that use the electricity) and returning through another line to the source.

Electric current - A flow of electrons; electricity. See Ampere (A), Amps.

Electrical grid - An integrated system of electricity transmission and distribution that links power plants and consumers, usually covering a large area.


Energy - The ability to do work. Stored energy becomes working energy when we use it. Power, measured in watts, is the rate of energy use. A lamp with a power rating of 15 watts operated for 1 hour uses 15 Watt-hours or 0.015 kWh of energy.

Energy payback time - The time required for any energy producing system or device to produce as much energy as was required in its manufacture. For solar electric panels, this is about 16-20 months.

-F- Fixed tilt array - A photovoltaic array set in at a fixed angle with respect to horizontal.

Flat-plate PV - Refers to a PV array or module that consists of no concentrating elements like mirrors or lenses. Flat-plate arrays and modules use direct and diffuse sunlight, but if the array is fixed in position, some portion of the direct sunlight is lost because of oblique sun angles in relation to the array.

-G- Grid-connected (PV system) - A PV system in which the PV array acts like a generating plant, supplying power to the electric utility grid.

-H- Hybrid system - A PV system that includes other sources of electric generation, such as wind or fossil fuel generators.

-I- Incident light - Light that shines onto the face of a solar cell or module.

Insolation - Sunlight, direct or diffuse, from “incident solar radiation.” Not to be confused with “insulation.” Equal to about 1000 watts per square meter at high noon in Dodge City.

Interconnect - A conductor within a module or other means of connection which provides an electrical interconnection between the solar cells. [Refer to UL Standard 1703]

Inverter - A device that converts DC electricity into AC electricity (single or multiphase), either for stand-alone systems (not connected to the grid) or for utility-interactive systems.


-J-

-K- Kilowatt (kW) - 1000 Watts. The kW is a unit of power. For example, one kW is enough power to illuminate 10 light bulbs at 100 Watts each.

Kilowatt-hour (kWh) - One thousand Watts acting over a period of 1 hour. The kWh is a unit of energy; 1 kWh is enough energy to power ten 100 Watt light bulbs for 1 hour or 10 25-Watt LED lamps for 4 hours.

-L- Line-commutated inverter - An inverter that is tied to a power grid or power line. The commutation of power (conversion from DC to AC) is controlled by the power line so that if there is a failure in the power grid, the PV system cannot feed power into the line. This ensures that the AC power output of the device matches the grid power frequency and phase and insures safety. However, systems that use line-commutated inverters cannot provide power to a home during an outage even though the sun is shining.

Load - Anything in an electric circuit that, when the circuit is turned on, draws power from that circuit.

-M- Maximum power point tracker (MPPT) - A power conditioning unit that automatically operates the PV-generator at its maximum power point under all conditions. An MPPT will typically increase power delivered to the PV system by 10% to 40%, depending on climate conditions and battery state of charge. You usually get more gain in winter and in colder weather due to the higher panel output. Most MPPT controllers are down converters - from a higher voltage to a lower one.

Megawatt - One thousand kilowatts or one million watts. In general, one megawatt is enough to meet the power demands of 1,000 average homes. It is important to keep in mind the difference between power and energy. Because a PV system only produces energy when the sun is shining, the number of homes a 1 MW system can operate is smaller. On average, 1 MW of solar photovoltaics can provide enough energy to operate 164 homes. However, the number of homes supplied per MW of PV varies based on many factors.

Meter - A device that measures a member’s electricity use.


Module - Also called a panel. A number of PV cells connected together housed in a sealed enclosure and having a standard size and output power; the smallest building block of the power generating part of a PV array.

Multicrystalline - Material that is solidified at such a rate that many small crystals (crystallites) form. The atoms within a single crystallite are symmetrically arranged, whereas crystallites are jumbled together, which reduces the device efficiency. A material composed of variously oriented, small individual crystals. (Sometimes referred to as polycrystalline or semicrystalline)

-N- Net metering - Net metering allows the solar system to send excess electricity back through the electric meter to the utility. In some cases, the meter actually runs backwards. With most modern AMI systems, separate meter registers record the amount of energy that flows in each direction. Net metering policies vary widely – be sure to understand yours. In the simplest form, the consumer’s bill will be for the net (kWh used – kWh generated). Most utilities do not pay cash if a system generates more than is used, but sometimes the excess will carry forward as a credit toward to the next bill.

-O- Ohm - The unit of resistance to the flow of an electric current. A circuit with a resistance of 1 ohm will allow a direct current of ampere to flow when 1 volt is applied.

One-axis tracking - A system capable of rotating about one axis, usually following the sun from east to west. Also called single-axis tracking

Orientation - Placement with respect to the cardinal directions, N, S, E, W; azimuth is the measure of orientation from north.

-P- Parallel connection - A way of joining two or more electricity-producing devices (i.e., PV cells or modules) by connecting positive leads together and negative leads together. When two identical cells are connected in parallel, the total current is the sum of the two cells while the voltage is that of a single cell.

Passive solar home - A house that uses building materials and construction to capture and store solar energy (heat) as opposed to active solar, which uses mechanical and energy-consuming devices to accomplish the same thing.


Peak load; Peak demand - The maximum load, or use, of electrical power measured during a given period of time, typically a day.

Photon - A particle of light that acts as an individual unit of energy.

Photovoltaic (PV) - Pertaining to the direct conversion of light into electricity.

Photovoltaic (PV) array - An interconnected system of PV modules that function as a single electricity-producing unit. The modules are assembled as a single structure, with common support or mounting. In smaller systems, an array can consist of a single module.

Photovoltaic (PV) cell - The smallest semiconductor element within a PV module to perform the immediate conversion of light into electrical energy (DC voltage and current).

Photovoltaic (PV) conversion efficiency - The ratio of the electric power produced by a photovoltaic device to the power of the sunlight incident on the device.

Photovoltaic (PV) efficiency - The ratio of electric power produced by a cell at any instant to the power of the sunlight striking the cell. This is typically about 9% to 14% for commercially available cells.

Photovoltaic (PV) module - The smallest environmentally protected, essentially flat assembly of solar cells and ancillary parts, such as interconnections, terminals, and protective devices, such as diodes, intended to generate DC power under unconcentrated sunlight. The structural (load carrying) member of a module can either be the top layer (superstrate) or the back layer (substrate). [Refer to UL Standard 1703]

Photovoltaic (PV) panel – Term often used interchangeably with PV module.

Photovoltaic (PV) peak watt - Maximum ‘rated’ output of a cell, module, or system. Typical rating conditions are 0.645 watts per square inch (1000 watts per square meter) of sunlight, 68 degrees F (20 degrees C) ambient air temperature, and 6.2 x 10-3 mi/s (1 m/s) wind speed.

Photovoltaic (PV) system - A complete set of components for converting sunlight into electricity by the photovoltaic process, including the array and balance of system components.

Polycrystalline--See Multicrystalline.

Power conditioning equipment - Electrical equipment, or power electronics, used to convert power from a photovoltaic array into a form suitable for subsequent use. A collective term for inverter, converter, battery charge regulator, and blocking diode.


Pyronometer - An instrument for measuring the intensity of sunlight or total hemispherical solar irradiance on a flat surface or "global" irradiance; Also called a pryanometer

-Q-

-R- Remote systems - Systems off the utility grid, out in the boondocks.

-S- Semiconductor - Any material that has a limited capacity for conducting an electric current. It generally falls between a metal and an insulator in conductivity. Certain semiconductors, including silicon, gallium arsenide, copper indium diselenide, and cadmium telluride, are uniquely suited to the photovoltaic conversion process.

Semicrystalline - See Multicrystalline.

Series connection - A way of joining photovoltaic cells or batteries by connecting positive leads to negative leads; when two identical cells are connected in series, the total voltage is the sum of the two cells while the current is that of a single cell.

Silicon (Si) - The most common semiconductor material used in making photovoltaic devices. A chemical element, atomic number 14, semi-metallic in nature, dark gray, an excellent semiconductor material. A common constituent of sand and quartz (as the oxide).

Sine wave inverter - An inverter that produces AC power whose voltage and current varies over time in a sine wave just like utility-supplied AC power. See Square wave inverter.

Single-crystal material - A material that is composed of a single crystal or a few large crystals.

Solar cell - See Photovoltaic cell.

Solar constant - The strength of sunlight: 1353 watts per square meter in space and about 1000 watts per square meter at sea level at the equator at solar noon. It increases at higher altitudes.

Solar energy - Energy from the sun. The heat that builds up in your car when it is parked in the sun is an example of solar energy.


Solar noon - That moment of the day that divides the daylight hours for that day exactly in half. To determine solar noon, calculate the length of the day from the time of sunset and sunrise and divide by two. Solar noon may be quite a bit different from 12:00 p.m.

Solar thermal electric - Method of producing electricity from solar energy by using focused sunlight to heat a working fluid, which in turn, drives a turbo generator.

Square wave inverter - The inverter that uses power semiconductor “switches” that can carry a large current and withstand a high voltage rating. The switches are turned on and off at a certain sequence, at a certain frequency to approximate an AC sine wave form power output. The square wave inverter is the simplest and the least expensive to purchase, but it produces the lowest quality of power. See Sine wave inverter.

Stand-alone (PV system) - An autonomous or hybrid photovoltaic system not connected to a grid. May or may not have storage, but most stand-alone systems require batteries or some other form of energy storage.

Stand-off mounting - Technique for mounting a PV array on a sloped roof, which involves mounting the modules a short distance above the pitched roof and tilting them to the optimum angle.

Storage - Storage refers to saving surplus electricity produced by a photovoltaic (PV) system. Generally, batteries are used as storage devices.

-T- Thin film - A layer of semiconductor material, such as copper indium diselenide, cadmium telluride, gallium arsenide, or amorphous silicon, a few microns or less in thickness, used to make photovoltaic cells. Commonly called amorphous.

Tracking array - PV array that follows the path of the sun to maximize the solar radiation incident on the PV surface. The two most common orientations are (1) one-axis tracking where the array tracks the sun east to west and (2) two-axis tracking where the array points directly at the sun at all times. Tracking arrays use both direct and diffused sunlight. Two-axis tracking arrays capture the maximum possible daily energy. Production depends somewhat on latitude and season, but typically, a single-axis tracker will provide 15% to 25% more power per day, and two-axis tracking will add about 5% to that.

Transformer - Steps AC voltage up or down, depending on the application. Transformers are used in the electric grid to step down the voltage of transmission lines (as high as 500,000 volts) to a distribution system voltage of 4,000 to 35,000 volts. Another transformer at the home steps the distribution voltage down to 240 Volts used in the home.

Two-axis tracking - A system capable of rotating independently about two axes (e.g., vertical and horizontal) and following the sun for maximum efficiency of the solar array. Also called dual-axis tracking.


-U- Utility-interactive inverter - An inverter that can function only when tied to the utility grid that uses the prevailing line-voltage frequency on the utility line as a control parameter to ensure that the PV system's output is fully synchronized with the utility power. See Line-commutated inverter.

-V- VAC - Volts AC

VDC - Volts DC

Volt (V) - A unit of measure of the force, or push, given the electrons in an electric circuit. Electric systems of most homes use 120 V for lights and small appliances and 240 V for major appliances like stoves, dryers, water heaters, and air conditioners.

-W- Wafer - A thin sheet of semiconductor material made by mechanically sawing it from a single-crystal or multicrystal ingot or casting.

Watt (W) - The unit of electric power, or amount of work, done in a unit of time. One ampere of current flowing at a potential of one volt produces one watt of power.

Watt-hour (Wh) - See Kilowatt-hour.

Waveform - The shape of the curve graphically representing the change in the AC signal voltage and current amplitude with respect to time. For utility-supplied AC power, the current and voltage change with time in a sine wave pattern.

-X, Y, Z-


Do you own your own home?

A) Yes – Go forward to the next question.

B) No – Consider non-site installed options, such as community solar.

Why are we asking? Homeowners are better candidates for solar energy. While it can be a good investment for the landlord, a renter is unlikely to invest in property they don’t own.

Have you already made your home more energy efficient?

A) Yes – Go forward to the next question.

B) No – You should upgrade your home first, then look at solar options.

Why are we asking? A homeowner should consider an energy-efficiency tune-up first. Making a home more energy efficient is less expensive and has a greater return on investment than most solar systems. By reducing the amount of energy used, members might be able to install a smaller, less expensive PV system to meet their

needs.

IS SOLAR RIGHT FOR ME?


Is your monthly electric bill greater than $100/month?

A) Yes – Solar may make sense.

B) No – With your low energy bill, you may not save enough to pay for your system.

Why are we asking? The cost of electricity produced by small PV systems is higher. Even though a PV system can generate a significant portion of the energy you use, members with relatively low energy bills might not save

enough money each month to pay for the investment in solar.

How much sun shines on your roof?

A) Full sun – Great! Go forward.

B) Shaded – The system may not produce enough power. Consider non-site installed options like community solar.

Why are we asking? Homes situated with full sun provide optimal opportunities for generating power. While solar PV can generate some electricity on cloudy days or with some shade, the output is much lower than full sun

and may not provide enough energy. However, there are alternatives. Perhaps a non-site installed option, like community solar, would be better. Or, the member might consider options for reducing shading on the roof.

Is your roof less than five years old?

A) Yes – Good. Go forward.

B) No – You may want to have your roof replaced first.

Why are we asking? A new roof, or at least one less than five years old, is a good starting point for solar because the array typically lasts 20 years or more. It wouldn’t be wise to install it on an older roof and later have to

remove the solar system to repair or replace the roof.


Does your roof face South, Southeast, or Southwest?

A) Yes – That gives you more energy.

B) No – You will get less energy from your system.

Why are we asking? Southern orientations are the most effective at producing energy, while East-facing, West-facing, and North-facing orientations aren’t nearly as effective.

Are you planning to live in your home at least five years?

A) Yes – Continue forward.

B) No – You may want to consider a short-term option rather than purchasing a solar system.

Why are we asking? Given the initial cost of PV systems, the return on investment could be long, even ten years or more. If a member plans to move, he or she won’t enjoy the benefits of that investment. And, because rooftop

solar is still relatively new, it’s difficult to say whether it will increase the home’s value when it’s time to sell.

How do you plan to pay for the system?

A) Cash

B) Loan or lease option

Why are we asking? Paying cash is the simplest, least expensive option. While alternative funding options are available, they should be researched carefully, and total costs should be considered. If it’s not cash, proceed

with caution.

Is your home free from neighborhood association restrictions that would affect system design and installation?

A) Yes – Good! Go forward.

B) No – Limitations may compromise the design and performance of your system.

Why are we asking? Depending on association limitations or rules, non-standard installation could compromise the design and performance of the system. Some homeowners’ associations restrict the installation of PV

modules on rooftops, especially if they’re visible from the street.


Do you have a simple, basic roof, or is does it have lots of levels, dormers, or other unique aspects?

A) Simple – Good! Go forward.

B) Complex – This may create challenges.

Why are we asking? Roof construction can have an impact on cost and ease of installation as well as the performance of a system. An experienced solar contractor will consider things like the slope, shape, and material

of a member’s roof before installing a solar system.

Have you looked into state and local incentives?

A) Yes – Good job; you’ve done your homework.

B) No – It’s a good idea to know what is available.

Why are we asking? Before proceeding, a smart candidate investigates federal, state, and local incentives that could reduce the system’s net cost and improve the overall bottom line. All members should consider getting professional tax and financial advice before making a decision. Be sure to check at the co-op for specifics on

interconnection requirements as well as any other assistance that may be available.

WHAT’S MY OUTLOOK? If you answered A to all questions, rooftop solar may be a good fit for you and your home.

If you answered B to several questions, you need to do a little more investigation. Look at some online resources and consider consulting with a solar professional.

Note: Not all B answers mean solar won’t work for you; some simply mean the system might be more expensive, produce less energy, or involve additional steps.


How to Use the Sample Proposal The next section includes a generic, but typical example of a proposal from a contractor. You’ll see notes about the information, questions to ask, and important considerations. This is in no way comprehensive, but it does provide some insightful information to help members evaluate their own proposals.


Notes to self

-Looks comprehensive with lots of graphs and economic analysis, but confusing!

-Energy savings are not very clear.

-Makes assumptions of the average utility rate, 5% escalation.

-Little info on contractor, qualifications, certifications, licenses, warranty, insurance or schedule

-Read the fine print!

-Not sure if based on actual location, rate, policies. Proposal should include output of PVWatts or

other solar performance computer model used.

Performance & Financial Analysis

Sample Solar Proposal

for Residential Customers

***Notes for page 1/Purchase Price and Fixed Cost

As noted, incentives and tax credits are significant, have a big impact

on economic success-check for details.

Tax credit not received until taxes are filed–can be a year before

received.

Rebates may take some time to be processed.

Take away: While net cost is only $7,217, buyer must pay $22k up

front.

$14,783 credit may take a year to be distributed.


Executive Summary

System Performance Summary

Purchase Price & Net Cost

Finance:

1

Financial Ratios

Ask to see actual energy

savings projection based on

your bills For past 10 years, average

increase was 2.2%

Using pre-tax dollars can be confusing

Not sure what this is

Economic success depends on

incentives; be sure to check for details

This is a fuzzy number. ***See comments on first page, “Notes”


The Cost of Doing Nothing

Utility Cost by Month

2

Is this based on a

house with

electric or gas

heat?

Graph suggests

that PV system

offsets nearly all

of the winter

utility cost –

may be

unrealistic.

Impressive, but

based on 5%

annual increase

Check if this is based on your

co-op’s policy


Carbon Footprint

•

•

3


Solar Electric (PV) System Summary

Contract Price Summary: Solar Electric (PV) System

4

Good to see monthly

production; also

would be good to see

how it compares with

home energy usage.

Ideal orientation and no shade. Great, but is this the actual situation?

This is a big

rebate. Make sure

it is available.

Impressive, but you

have to write a $22k

check to get this.

Be sure to check with a tax advisor

Is there space for

this on the roof?


How to Interpret Financial Ratios and Measures

5 Be sure to understand these concepts.


Assessing Option Value

6

This is not widely accepted. May be true but a future

buyer may not value solar.


Assessing Option Value, Continued

7 Check if homeowner

keeps them.


Utility Energy Summary: Electric

Electric by Month (kWh) 1 2 3 4 5 6 7 8 9 10 11 12 Total

Entered into Software (historical)

Monthly Use 580 658 698 800 1000 1300 1450 1600 1250 750 650 600 11336

Historical Cost $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0 $0

Estimated by Software at Current Rates (includes any planned energy increases)

Estimated Use 580 658 698 800 1000 1300 1450 1600 1250 750 650 600 11336

Current Cost $58 $66 $70 $80 $100 $130 $145 $160 $125 $75 $65 $60 $1134

Baseline Use After Efficiency

580 658 698 800 1000 1300 1450 1600 1250 750 650 600 11336

Baseline Cost After Efficiency

$58 $66 $70 $80 $100 $130 $145 $160 $125 $75 $65 $60 $1134

Post Project Use (15) 78 (41) 55 267 567 674 794 535 12 76 43 3035

Post Project Cost $0 $6 $0 $2 $27 $57 $67 $79 $53 $1 $8 $4 $304

Net-Meter Credit $(2) $0 $(4) $0 $0 $0 $0 $0 $0 $0 $0 $0

8

Check co-op net

metering policy.

Use of average

cost=bad

Should be based

on actual utility

rate

Are these #’s from actual utility bills/billing

history?


Cash Flow Details for the System

Cash Flows in Year 0 1 2 3 4

Gross Cost: PV (22000) 580 658 698 800

O&M Cost: PV 0 (57) (58) (60) (61)

Ref: Utility Bill Savings with Inflation Applied 0 872 913 958 1003

Utility Bill Savings as Gross Income Dollars 0 1211 1268 1331 1393

Solar Electric (PV) Incentives

Austin Energy - Residential) Solar PV Rebate ($ 2 per watt AC) 11690 0 0 0 0

Federal Tax Credit (30% of Net Cost at Installation) 3093 0 0 0 0

Total Incentives 14783 0 0 0 0

Net Annual Cash Flow (7217) 1154 1210 1271 1332

Cumulative Cash Flow (7217) (6063) (4853) (3582) (2250)


O&M Cost: PV (63) (65) (67) (69) (71)

Ref: Utility Bill Savings With Inflation Applied 1052 1104 1158 1214 1273


Net Annual Cash Flow 1398 1468 1541 1617 1697

Cumulative Cash Flow (852) 616 2157 3774 5471

9

These are received in year 1,

not year 0. Changes cash

flow.

Not easy to check; includes escalation,

performance degradation; assumes energy

use doesn’t change over 25 years.


Cash Flow Details for the System, Continued


O&M Cost: PV (83) (86) (88) (90) (93)




Cumulative Cash Flow 17610 20003 22518 25161 27937


O&M Cost: PV (96) (98) (101) (104) (107)






O&M Cost: PV (72) (75) (77) (79) (81)





10


Cash Flow Details for the System Continued


O&M Cost: PV (110) 0 0 0 0

Ref: Utility Bill Savings with Inflation Applied 2769 0 0 0 0




11


Other Assumptions Used in this Analysis

Solar Resources: Flat-Plate

12

These are values for the nearest monitoring station. They do

not include shading or local effects at the house. Was

performance estimate in this proposal based on these or actual

conditions at the site?

Based on what?

Examples?

These are important!

Check with tax

advisor

25 years is ok for system; most

inverters don’t last that long.

This is high.

Check policy!

???

This does not appear to be used in analysis.

5% discount rate too low for residential projects. 10 – 15% more

representative. Has a big impact on NPV.

Important

to note!


Additional Resources Touchstone Energy Public website: www.TouchstoneEnergytouchstoneenergy.com

PDFs of Solar fact sheets: www.touchstoneenergy.com/our-energy-expertise/energy-choices/

Energy efficiency tips, programs, videos, articles: www.TogetherWeSave.com

Design files for editing fact sheets: www.cooperative.com/interest-areas/touchstone/residential/Pages/Energy-Efficiency.aspx

NRECA SUNDA project - articles, finance, evaluation tools: www.cooperative.com/public/bts/sunda/Pages/default.aspx

NRECA Solar Resources - Community solar, interactive map, case studies: https://www.cooperative.com/public/

bts/sunda/Pages/More-NRECA-Resources-for-Solar.aspx

NRECA Solar Communications Toolkit: www.cooperative.com/public/bts/sunda/toolkit/Pages/default.aspx

USDOE – Renewables: www.energy.gov/eere/renewables

Database of State incentives for Renewables: www.dsireusa.org/

National Renewable Energy Lab: www.nrel.gov/

Smart Electric Power Alliance: www.sepapower.org/

http://www.touchstoneenergy.com/

http://www.touchstoneenergy.com/our-energy-expertise/energy-choices

http://www.togetherwesave.com/

http://www.cooperative.com/interest-areas/touchstone/residential/Pages/Energy-Efficiency.aspx

http://www.cooperative.com/interest-areas/touchstone/residential/Pages/Energy-Efficiency.aspx

http://www.cooperative.com/public/bts/sunda/Pages/default.aspx

https://www.cooperative.com/public/bts/sunda/Pages/More-NRECA-Resources-for-Solar.aspx






http://www.cooperative.com/public/bts/sunda/toolkit/Pages/default.aspx

http://www.energy.gov/eere/renewables

http://www.dsireusa.org/

http://www.nrel.gov/

http://www.sepapower.org/


NOTES


Email: [email protected] Telephone: (703) 907-5500 Fax: (703) 907-5554

Touchstone Energy Cooperatives 4301 Wilson Boulevard Arlington, VA 22203-1860

mailto:[email protected]

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