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Photovoltaic Types

  • Single-Crystal Cells are usually the most efficient.  This is because the more perfect a crystal the PV cell is, the easier it is for electricity to move through the material. However, the more perfect a crystal, the more expensive it is to manufacture. Single-crystal silicon cells can be easily identified by their distinctive round or psuedo-square appearance. 
  • Multi-Crystalline Cells are similar to ones made from Single-Crystal. 
  • Thin-Film Modules are made by spraying non-crystalline silicon material directly onto the protective glass.  There are no individual cells. Commonly used for “Solar Shingles,” thin-film is less expensive and weighs less, but is also currently less efficient.
  • Fabric & Dye-Based photovoltaic systems are currently under development on a microelectronic scale.

PV Applications

  • A Grid Interactive Power System (also called Grid-Tie, Grid-Connected) uses electronic equipment to directly connect the PV array to the utility service hook-up in your house.  This type of system functions only when power is also available from the utility and from the sun.  Direct-tie systems are used to offset the energy use of a building, helping reduce pollution and dependence on fossil fuels. 
  • An Uninterruptible Power System is a special type of grid-interactive system with batteries. A UPS can function as a stand-alone system, providing power to critical loads if the utility power fails.  A UPS has all the benefits of a Grid Interactive system, plus the added benefit of increasing power reliability at a building.

Advantages of Photovoltaic Systems

  • •Automatic, Reliable Operation
  • •Low Noise, No Moving Parts
  • •Low Operating Cost
  • •Non-Polluting
  • •Modular, Portable
  • •Non-Flammable

If You Can Say “YES” To One Of The Following, A PV System May Be a Good Choice For You

ü    Concerned About Power System Reliability

ü    Interested in a Healthy Environment

ü    Want to Become More Energy Independent

Will PV be Effective Where I Live?

Solar energy is one of the most reliable forms of energy in the world.  In fact, most energy ultimately has come from the sun. Even under adverse weather conditions, a guaranteed minimum amount of energy will be available daily from the sun. 

The amount of power available from the sun at any one moment depends on the angle of the sun’s rays hitting the PV array and the prevailing weather conditions.  The angle of the sun’s rays hitting the array depends on the latitude where the array is located, the tilt of the array, the direction the array is facing, the hour of the day, and the season of the year.  Prevailing weather includes factors like cloud cover, air clarity, temperature, and wind chill.  Solar insolation maps take into account all of these factors typical for a geographic region.  As shown on the Department of Energy’s (DOE) solar resource map, PV array systems in New England can access on average a maximum of between 5 and 6 peak sun hours a day.  These numbers vary monthly.  In the winter, less peak sun hours are available, but this is slightly offset by the fact that photovoltaics are more efficient in cold weather, and will produce more power.  Since these are averages, the actual amount of solar energy available at a particular site, or for a specific day, may be significantly different.

Electricity Prices

Even if your site does not seem to have as much sun as other areas of the world, this does not necessarily mean a PV array won’t be cost effective for you.  The value of the electricity it produces is also important.  Areas with high electric rates are often good candidates for PV.

What Do I Need to Use FREE Energy From the Sun?

Array Mounting Structure
The best angle for an array to be at is perpendicular to the sun’s rays.  A tracking system will automatically orient the array properly, allowing the maximum amount of sunlight to be harvested.  If the array is to be permanently fixed in place, mounting the array at an angle equal to the location latitude will keep the array perpendicular as much as possible, and will produce the best results.  Most roof pitches in New England are 10/10 to 10/12, nearly optimal for a PV array.

Site Selection
The PV array should be sited in an area free of shading for as much of the day as possible.  Some shading is permissible during the early morning and late evening hours (before 9 AM and after 3 PM), but preventing the array from being shaded provides more power and prolongs the array life by keeping an even temperature over the array.  The best direction for an array to face is due South. 

Building Integrated PV
A building integrated PV array is part of the necessary structure of the building walls, windows, or roof. The array provides dual functions of power generation and protection from the elements.  These types of arrays may be very cost-effective, since the array is serving a dual-purpose, and a budget is already allocated for building material. Electricity production needs only to offset any higher incremental costs.

Permits
A building permit from town authorities may be required by the town to allow legal construction of a PV array on your property.  Depending on zoning requirements, a public zoning hearing may also be necessary to obtain a variance, for example if the array is to be roof-mounted in a historical district.  An electrical permit is required and can be obtained by your electrician.

System Protection - The National Electric Code
The National Electric Code (NEC) was established in 1987 to ensure safety in electrical systems.  When a system is installed, NEC requirements must be carefully followed, or it will fail inspection. Additionally, many states require all electrical equipment to be installed by a licensed electrician.

Utility Interconnection & Net Metering
As a result of the Public Utility Regulatory Policy Act (PURPA) of 1978, all utilities are required to purchase power from a customer who produces an excess of energy, as long as that energy that meets certain quality specifications.  In many states, including all of New England, the active energy buy back policy is termed “net metering.”  Under this policy, the utility rates the energy the customer produces at a 1:1 ratio to the power consumed.  If, at the end of the month, the consumer has produced more power than consumed, the excess kWh’s are labeled “net excess generation.”  Net excess generation is treated differently by state.  In some states, the excess kWh’s are rolled forward as a credit to the next month’s bill.  For a customer, it is the best metering policy in the country.  In other states, net excess generation is valued at “avoided cost,” which is what your energy would have cost the utility to produce (or buy elsewhere in deregulated states).

An agreement with your utility is needed to legally sell power on the grid and receive your full, entitled benefits.  In deregulated states, separate agreements are needed with both the electric distribution company and your power supplier. 

Protecting Your Investment in a Power System

Insurance

A renewable energy system is a valuable investment in the environment, in your property, and in your energy needs.  PV modules are certified to withstand severe environmental conditions.  However, it is recommended that you verify that your existing homeowner’s policy is sufficient to cover the value of the system, and to meet any utility company requirements for liability insurance to protect utility personnel.  Most homeowner’s policies are already adequate.

Maintenance
  • Checking the output of your system periodically will help you verify if your system is operating properly.
  • Regular inspection of the outdoor equipment should be done annually and after unusually severe weather, to ensure the mounting system is secure and the PV array is unobstructed and undamaged.  
  • In areas of high air pollution, the array may occasionally need to be cleaned with soft cloth and mild glass cleaner.
  • If your system has batteries, inspection of the batteries for voltage differences and terminal corrosion should be done annually.  The batteries are expected to ast 10 years before replacement is advised. 

KW Management Can Help You Reach Your Energy Goals

KW Management, Inc’ seeks to make a positive impact on quality of life and the environment by promoting clean, efficient, and renewable energy technologies. We work with world-class manufacturers to provide excellent equipment, analysis, and project management services in the most cost-effective manner, and to provide the information needed for customers to make choices about the energy options that best meet their individual goals.

With our packaged systems, all of the component selection, sizing, and safety compliance has already been done for you.

We also provide these essential time and money-saving services
  • Site assessment.
  • Project management.
  • Hardware and labor warranties.
  • Handling of utility interconnection.
  • Maintenance contracts.
  • Custom project design.

An Important Note…

Often the most effective way of reducing environmental impact and utility bills is to decrease electricity consumption.  By using the most efficient appliances available, such as those with the Energy Star rating, you will make an impact! Energy efficient appliances can never produce energy, or provide power in emergencies, so you still may choose to invest in a PV system.  However, you should be aware that a PV system functions at its best with energy efficient appliances.

Interested?

So we can offer you the best service, please take a moment to fill out the enclosed questionnaire and return it.  We will review the information you provide and contact you to answer any questions you may have or schedule a site visit[1]
The Federal Government has made a commitment to promote solar energy to enhance the market competitiveness of the United States, to increase the nation’s energy security, and to mitigate pollution.  In 1997, the Million Solar Roofs Initiative began. The goal of the program is to install one million solar energy systems on buildings across the United States by 2010.  The MSR Initiative operates through State and Local Partnerships coordinated by the US Department of Energy’s Regional Offices.  Each Partnership commits to install at least 500 PV systems, and acts to help identify and remove barriers to installing these PV systems.  Some activities are educating code officials, identifying financing opportunities, and promoting net metering.  For more information, and to find out about programs in your area, please visit the MSR Initiative web site at www.MillionSolarRoofs.org.

Site visits within 50 miles of KW Management headquarters in Nashua, NH are free of charge.  Contact the office about other locations.
 

KW Management, Inc.
55 Lake Street | Nashua, NH 03060
Phone: 603-598-0181 | Fax: 603-598-5188
Email:info@kwmanagement.com

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