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Solar
Solar Technologies Overview
Solar energy is the basis for almost every form of energy we use. Heat from the sun indirectly produces wind power, biomass, and hydroelectric power. However, discussions about solar energy usually refer to the ways the sun’s energy can be used to directly generate heat, lighting, and electricity.
Solar water heating technology is the most common technology associated with solar energy, but there are other types of solar technologies such as photovoltaics (PV), passive solar, solar heating and cooling, and solar thermal concentrating systems which are becoming more popular.
How Does Solar Energy Work?
Energy radiating from the sun is responsible for providing all the heat, energy, and light necessary for sustaining life on earth. Energy from the sun determines the planet’s weather patterns and powers many important ecological processes and cycles, such as photosynthesis. The goal of solar technologies is to harness the solar energy reaching earth’s surface to generate electricity and to heat and cool buildings. Below are descriptions of the different types of solar technologies in use today.
Solar Photovoltaic (PV)
Solar PV technology uses semiconductors to produce electricity. A PV cell consists of a positively charged and negatively charged semiconductor placed side by side to form a diode, or an electrical field that allows for a one-way flow of electrons. When sunlight hits the positively charged semiconductor, the force of the impact causes electrons to separate from their atoms and travel to the negatively charged semiconductor. However, these electrons are unable to bond with the electron-saturated atoms in the negative semiconductor. Looking for somewhere to go, these electrons are transferred to a metal conductor strip that channels these electrons into an electrical current. It is this flow of electrons that can power any devise that uses electricity. To complete the circuit, these electrons then travel back to the positively charged semiconductor through a second metal conductor. Multiple PV cells can be combined to form a solar PV panel. These
panels come in many different sizes depending on the amount of
electricity they need to produce. Multiple panels can also be combined
to form a solar array (Figure 1).
Figure 1: Solar PV cell, module and array. Source: U.S. Department of Energy
There are three generic types/approaches for manufacturing viable solar PV technologies: discrete cells on wafers sawed from silicon ingots (most common); discrete cells on silicon wafers cut from multicrystalline ribbons; and the deposition of thin layers of non-crystalline-silicon materials on inexpensive substances (amorphous panels). A number of research efforts are currently underway to advance the use and distribution of amorphous panels as these hold the prospect for being more efficient and cheaper than traditional solar arrays. More information on the state of research into amorphous solar panels can be found on the U.S. Department of Energy website.
Solar Thermal
There are three major solar thermal technologies:
- Solar heat collectors come in two types, air heaters and water heaters. Air heaters use small fans to circulate air through a glass covered, insulated box on the south side of a building. The box contains a black metal plate that is heated by the sun providing solar heated air for the building. Water heaters circulate a fluid, either water or, in colder climates, an antifreeze solution through carefully designed metal solar collectors that transfer the sun’s heat to the fluid and provide domestic hot water for bathing and washing.
Figure 1: Solar Heat Collector. Source: Bay State Energy
- Solar Thermal Concentrating Systems produce intense heat that can be used in the industrial sector to generate electricity. To generate this heat, solar thermal systems use reflective mirrors to concentrate sunlight onto a central receiver. The heat is then fed directly into a heat engine, which generates electricity.
- Passive Solar refers to the way a building is designed to maximize the
sun’s energy. Buildings that utilize passive solar design often reduce
their electricity, heating, and cooling demands which can significantly
reduce energy costs. Key aspects of passive solar design include
building orientation, building design, and building materials. For
example, a building could be oriented to maximize the amount of
sunlight entering the structure, thereby reducing the electricity
needed to light the facility.
For more information on the basics of solar energy and solar technology please go to the Resources section.
Benefits and Barriers of Solar
Benefits:
- Zero Greenhouse Gas Emissions: Solar is one of the cleanest forms of energy. No carbon emissions or any other types of emissions are produced from generating electricity or capturing heat from the sun.
- Reduced Energy Costs: Solar energy is a free and unlimited source of energy. With solar PV systems, there is also the potential for net metering, where the electricity generated beyond the site’s energy requirements can be sold back to the grid. While the manufacturing and installation costs are high for solar PV, these costs are likely to drop as the market expands.
- Minimal or No Impact on Installation Site: Solar installations are often placed on top of existing structures, resulting in no additional impact to the site. Most ground level solar technologies also have small space requirements.
- Economic Development: As the market for solar technologies expands, jobs in solar installations, research, and development will be created.
- Energy Security: Solar energy is a free source of energy that is available locally and free of price fluctuations.
- Low Maintenance Requirements: Solar technology is easy to maintain once installed.
Barriers:
- High Manufacturing and Installation Costs: The market for solar technology has historically been relatively small. While this is rapidly changing, it does mean that solar is often an expensive clean energy option with less favorable pay-back rates than other technologies.
- Power Quality May Be Intermittent: While the sunlight is a free and unlimited energy source, the heat and electricity produced from solar technologies is dependent on the amount of sunlight received.
Installing Solar
Below are two checklists to help you navigate the solar installation process. The first is a solar photovoltaic checklist and the second is on solar thermal systems.
| Solar Photovoltaic Checklist |
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Step 1 - Location of Site: In order to have an effective solar installation, you
should ensure your site has high quality and continual access to
sunlight. Solar PV systems require essentially shade-free placement.
Most installations are installed on roofs to maximize exposure to sun
light and are angled equal to the latitude of the location. In
Massachusetts, this latitude is 42 degrees north, meaning that panels
should be angled 42 degrees and face the south. The City of Boston has created an interactive solar map, Solar Boston, that provides perspective on the amount of roof tops that could feasibly have a solar PV installation in the City. |
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Step 2 - Utility Interconnection Standards and Issues: Work with your
utility to determine how your solar system will connect to the
electricity grid and if there is an opportunity for net metering. |
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Step 3 - Financing and Incentives: Solar PV installations are more costly than traditional fossil fuel based systems. As such, it’s important to ensure you have the proper funding to advance your solar installation. For more information on financing, see the Financing section below or the Financing Page of the Toolkit. |
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Step 4 - Permits, Electrical & Zoning Requirements: Work with your local planning department to ensure that there are no local laws or regulations that might prohibit or delay your solar installation. |
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Step 5 - Fatal Flaw Analysis: A fatal flaw analysis identifies prohibitive
constraints that prevent the installation of the solar systems, such as
space availability, building structural integrity, load-capacity ratio,
and regulatory or managerial issues. Here is an example of such an
analysis and a document that can guide you through solar site selection (including fatal flaw issues) |
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Step 6 - Capacity of the Solar Electric System (kW): Do you want your system to supply 100% or a portion of your electricity demand? To evaluate your total electricity demand, your municipality should conduct an Energy Audit. The system should be as close to the electric meter as possible to minimize wire transmission losses. |
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Step 7 - Select an Installer: Determine who will be the supplier of your solar array. Consider using a local manufacturer and a local installer to help ensure your resources stay in the local economy. |
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Step 8 - Discuss Insurance & Liability Issues: Work with your municipal legal team to identify what types of insurance and liability coverage are required. |
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Step 9 - Conduct Public Outreach: To ensure as little resistance as possible, hold community forums to educate citizens about your solar project. Provide information on how this will make your community more sustainable, reduce the demand on foreign oil, provide an educational opportunity for local schools, and any other local priorities. |
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Step 10 - Mounting of Solar Array: When mounting your array, you can choose flat mounting, rack structures, pole mounting, or tracking structures. Which option you choose depends on the size and location of your system. For more information on mounting types, see the Massachusetts Renewable Energy Trust. |
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Step 11 - System Maintenance and Monitoring: Make sure you have a system
in place to monitor your solar array and to conduct regular maintenance
– even though it should be minimal. Consider using your solar
installation as an educational platform. |
If obstacles arise through the process listed above, consider working with appropriate agencies to modify existing regulations, ordinances/by-laws, zoning, etc. However, multiple obstacles may indicate that this energy type is not suitable for your community. If this is the case, consider pursuing an alternative clean energy type.
| Solar Water Heating Checklist |
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Step 1 - Consider Economics of a Solar Water Heater: A solar water heater can cost more to install than a traditional water heating system, but the paybacks can exceed the cost. Consider: the amount of hot water you use, your system's performance, the cost of conventional fuels (natural gas, oil, and electricity), and the cost of the fuel you use for your backup water heating system, if you have one. |
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Step 2 - Location of Site: In order to have an effective solar installation, you should ensure your site has high quality and continual access to sunlight. Most installations are installed on roofs to maximize exposure to sun light and are angled equal to the latitude of the location. For solar water heating systems, there needs to be enough floor space near the existing hot water tank for an additional storage tank and the distance between the system and the tank should be minimized to reduce pipe runs and heat losses. |
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Step 3 - Financing and Incentives: Solar installations are more costly than traditional fossil fuel based systems. As such, it’s important to ensure you have the proper funding to advance your solar installation. For more information on financing, see the Financing section below or the Financing Page of the Toolkit. |
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Step 4 - Determine the Correct Size of Your Solar Water Heater: Sizing your solar water heating system involves determining the total collector area and the storage volume you'll need the system to meet. |
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Step 5 - Investigate Local Ordinances, By-laws, and Regulations: Before installing a solar water heating system, you should investigate local building codes and zoning ordinances/bylaws, as well as any special regulations pertaining to the site - including if you need a building permit to install the solar system. |
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Step 6 - Fatal Flaw Analysis: The fatal analysis identifies prohibitive constraints that prevent the installation of the solar systems, such as space availability, building structural integrity, load-capacity ratio, and regulatory or managerial issues. Here is an example of such an analysis and a document that can guide you through solar site selection (including fatal flaw issues) |
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Step 7 - Select an Installer: Determine who will be the supplier of your solar heat collector. Consider using a local manufacturer and a local installer to help ensure your finances stay in the local economy. |
|
Step 8 - Discuss Insurance & Liability Issues: Work with your municipal legal team to identify what types of insurance and liability coverage are required. |
|
Step 9 - Conduct Public Outreach: To ensure as little resistance as possible, hold community forums to educate citizens about your solar project. Provide information on how this will make your community more sustainable, reduce the demand on foreign oil, provide educational opportunities for local schools, and any other local priorities. |
| |
Step 10 - System Maintenance and Monitoring: Make sure you have a system in place to monitor your solar array and to conduct regular maintenance – even though it should be minimal. Consider using your solar installation as an educational platform. |
If obstacles arise through the process listed above, consider working with appropriate agencies to modify existing regulations, ordinances/by-laws, zoning, etc. However, multiple obstacles may indicate that this energy type is not suitable for your community. If this is the case, consider pursuing an alternative clean energy type.
Legislation
- Commonwealth of Massachusetts Solar Access Laws: The Commonwealth of Massachusetts has a number of provisions in the General Laws of Massachusetts that allow for the creation of voluntary solar easements and authorize zoning rules that prohibit unreasonable infringements on solar access. Additionally, the statutes allow for communities to authorize zoning boards to issue permits creating solar rights. Below are links to four of the Massachusetts General Laws pertaining to solar access:
- Green Communities Act: Among other provisions, the Green Communities Act enables the Massachusetts Renewable Energy Trust to continue funding clean energy projects, including solar initiatives.
In addition to Massachusetts state laws governing access to solar energy, individual municipalities may have ordinances that affect solar installations. Check with your local planning and building department to see if any relevant ordinances are in place.
Financing
Like other clean energy technologies, there are many options for financing solar energy projects. While some of the options are specific to solar energy, there are others that apply to many different types of clean energy technologies. Below is a list of solar specific financing that is available. For more information on these initiatives and all other financing options, please refer to the Financing Clean Energy Page.
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Commonwealth Solar: This initiative, administered by the Massachusetts Renewable Energy Trust, provides rebates through a non-competitive application process for the installation of PV projects at residential, commercial, industrial, and public facilities. Starting in 2008, this program has $68 million in funding over the next four years. Project eligibility includes:
- The applicant is a customer of a Massachusetts investor-owned electric utility, or of a Municipal Light Plant that has joined the Massachusetts Renewable Energy Trust
- Non-residential projects up to 500 kW and residential projects up to 5kW
- The applicant is a customer of a Massachusetts investor-owned electric utility, or of a Municipal Light Plant that has joined the Massachusetts Renewable Energy Trust
- Green Communities Division: The Green Communities Act provides up to $10M annually in grants and loans for communities that qualify as a Green Community as specified in the Act. The Green Communities Division in DOER is responsible for developing guidelines for qualifying communities and administering the program. Funds are available to qualifying communities for renewable energy projects.
- MA Department of Energy Resources Energy (DOER) Audit Program: This program provides funding for municipalities to identify projects to reduce energy costs by providing energy audits and conducting clean energy technology feasibility studies.
Examples
- Ashland High School:
In 2003, the town of Ashland was in the process of designing a new high
school, and wanted to take an environmentally and fiscally responsible
approach. Through financing through the Massachusetts Renewable Energy
Trust's Feasibility Study program, the town's design team was able to
explore solar orientation, site protection, lighting systems, HVAC
system, and water efficiency options. After conducting the study the
school decided to forge ahead with plans to incorporate a 33.6 kW
photovoltaic system at the school.
- Brockton Brightfields: This pamphlet includes information on the City of Brockton’s Brightfield; a redeveloped former manufactured gas plant site that now is home to a solar energy generating station. The pamphlet also includes contact information for more information on the Brightfield’s project. To learn more about the Brockton Brightfield, see the Brockton Case Study.
- Charlemont Wastewater Filtration Facilities: Supported by the Massachusetts Renewable Energy Trust, the Charlemont Sewer District installed a 14.5 kW solar PV system near its filtration beds in 2005. The 96 solar PV panels installed provide electricity to power the pumps, motors, and lights used by the wastewater treatment facility.
Resources
- Clean Energy States Alliance: The CESA produces cases studies, reports and program guides on clean energy. The studies on their website include information on financing, strategies to foster solar hot water system deployment, mainstreaming solar electricity, and much more.
- Massachusetts Renewable Energy Trust (Trust): provides a variety of solar electricity installation and buying guides along with permitting and approval guides. Additionally, the Trust has a section dedicated to solar PV technology.
- National Renewable Energy Laboratory - Heat Your Water With the Sun: Guide that provides information on how solar water heaters work, how they can be used, their benefits, and how to purchase one.
- NStar Solar: NSTAR Solar is a program designed to help customers who own their own home receive installation rebates for installing photovoltaic (PV) systems. Participants in the program receive a free home energy assessment and a solar assessment meeting.
- NYSERDA: The New York State Energy Research and Development Authority published a guide to installing solar electric systems. The guide includes information on how to choose an installer, determining energy output and savings and obtaining permits and approvals.
- Solar Electric Power Association: The Solar Electric Power Association is a nonprofit organization that is comprised of utility and solar industry members. The website contains information about the basics of solar power, installation directory, a resource library, and utility solar programs among other information.
- Solar Energy Industries Association: SEIA is a national trade association for the solar energy industry. Their mission is to effectuate federal policy that reduces barriers and improves market conditions for the US solar energy market. SEIA’s website contains a variety of information on state and federal issues, solar technology and products and advocacy efforts.
- US Department of Energy’s Solar Technologies Program: US DOE program that focuses on the advancement of cost-effective solar-energy technologies. Website contains information on solar systems, the Solar American Cities program, and the US DOE’s efforts to remove barriers to the widespread adoption of solar technologies.
- US Department of Energy Solar Water Heaters: The Office of Energy Efficiency and Renewable Energy provides information about solar water heaters including how to select, install and maintain solar water heaters.
