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Types of Clean Energy

Community Solar


Takoma Park Solar Co-op: Takoma Park Solar Co-op has launched! Homeowners in the Takoma Park and Silver Spring area are organizing a neighborhood solar co-op with Community Power Network. Learn more or sign-up for the co-op online.

Rockville Solar Co-op: Rockville Solar Co-op has launched! Homeowners in Rockville (and beyond) are are organizing a neighborhood solar co-op with Community Power Network. This effort is supported by a Department of Energy grant to the Metropolitan Washington Council of Governments (COG).

  • Learn more at a free information session on April 18th, from 10 a.m. until noon, at at the Pepco-Rockville Customer Service Center, at 201 West Gude Drive.
  • Learn more at Rockville Solar Homes or to register or receive future updates, email

Maryland: Homeowners in Maryland can sign-up to take advantage of pre-negotiated rates for a solar panels and installation. Groundswell, with a team of community leaders, has screened solar contractors and chosen Sustainable Energy Systems for this bulk purchase. To learn more or register your interest, visit Groundswell Solar, Made Simple

Montgomery County DEP posts event information and provides outreach to promote sustainability opportunities, but is not otherwise involved in the organization of these initiatives.


What is Community Solar?

Community solar describes a number of efforts to help groups of homeowners, businesses, or non-profits (such as churches) install solar.

What Types of Community Solar Models are there?

Aggregate or bulk-buy models group the purchasing power of homeowners together to bring down the cost of installing solar. Vendors can save money by reducing marketing and travel costs (since the purchasing group generally consists of homes located within the same geographic area), and then pass those savings onto the group.

There are generally two types of bulk-buy models that have been actively used in the DC metro area:

  • Solar Co-ops

One model is where homeowners leverage their collective buying power to go solar as a group in order to get a discount. The group solicits bids from area solar installers and then identifies and selects a vendor that meets their community’s needs. That vendor installs all of the systems for the group, allowing them achieve economies of scale and pass those savings onto the members. This is one model that Community Power Network facilitates. As of Fall 2014, CPN has supported 17 solar co-ops in the DC, MD, VA, and WV area.

  • Solarize Programs

A second model is where an entity (typically a local nonprofit or organization) develops and runs the procurement process and then invites homeowners to participate. Often these solarize programs have larger numbers of participants than co-ops and can be a region-wide initiative. Solarize projects across the nation tend to fit this model. As of Fall 2014, there have been Solarize projects in Fredrick, MD, Leesburg, VA, and Charlottesville, VA.


What Should One Look for when Exploring these Opportunities?

As a property owner, you will want to consider which model best serves the needs of your community and you as an individual. Some models require more commitment from participants, but that also means they have more control over the process.

Be sure to read any agreements very carefully. Supporting organizations often do collect a small fee as part of the deal, so be sure you are aware of those costs. Also check to see how the organizers and installers will handle any follow-up or issues that may arise during or after the process.


What is Virtual Net Metering or Solar Gardens?  Isn't that Community Solar?

Virtual net metering, also known as virtual aggregation or community solar gardens, refers to the ability of multiple entities to engage in a solar project together and share the benefits of selling power to the local electric utility, offsetting their own energy use. Currently in Maryland only agricultural customers, non-profit organizations, and municipal governments or their affiliates can participate in such a project. A law has been introduced in the MD General Assembly that would expand this group to allow residents to participate; the policy is currently under study by the MD Energy Administration.


Note: The terminology used here is not standard and there may be different uses or overlapping uses of the terms “aggregate”, “community”, or “solarize”. Be sure to read about the process to find the model you’re interested in.


Solar Energy

Solar energy systems harness the energy of the sun to generate electricity or heat water. Both types of systems are appropriate for buildings in the Montgomery County area:


Is a Solar Energy System Right for Me?

The first thing to consider when determining whether a solar system is appropriate for your home or bushiness is where to put it. To get the best result, photovoltaic panels or solar heat collectors need a southern-facing location with limited or no shade coverage. This location can be a roof or a scaffold created specifically for the system.

Other considerations include your annual electricity usage and the financial resources available to install such a system.

If you are installing solar photovoltaic panels, you may want to consider how much clean energy you hope to produce to offset the electricity you purchase. A general estimate for solar PV size, electricity production, and cost is provided below:

Estimate of Solar PV Cost and Size
  Size Electricity Produced
1 kilowatt (kW) ~100 square feet 1,300 $9,000–$11,000


An installer can estimate the appropriate size of a solar PV system by considering three main factors:

  1. Available space for installing the system

  2. Image of solar panels.

    The building's annual electricity usage

  3. Financial resources available

When the panels are installed, the installer will tilt them to the best angle to receive sunlight. Using special instruments, a solar installer can help to assess the building's sun energy potential. This will also help to gauge how much electricity the solar system can produce.

To learn more about what might work for you visit the Find Solar Web site. Here you can find a tool to estimate the system size a commercial or residential building could support and what incentives might be available. The tool can help you estimate system costs, electricity cost savings, and the number of years in which the system will pay for itself. The Web site also provides a list of available solar installers in the area.


Selecting and Finding a Service and Product Provider

When shopping for an installer, always check for relevant licenses, request references and a list of itemized costs, and get multiple quotes. The following sites include lists of qualified providers:

Additional qualifications to inquire about include master electrician. Ask whether staff on hand are certified electricians or master electricians and ask to see the County certified credentials.


Additional Resources and Incentives for Solar Energy

Learn more about:


Wind Energy

Using wind to do work or generate electricity is not a new idea, but wind is becoming a popular renewable resource for broad-scale electricity generation and on-site use.


Is a Wind Energy System Right for Me?

There are several siting issues to consider before purchasing a system.

  1. Available wind resources. It is crucial to determine whether there is enough wind to sustain a small wind turbine. The U.S. Department of Energy suggests that consistent winds of 9.8 to 11.5 miles per hour are necessary to sustain a small turbine and generate enough electricity to make your system cost-effective. Visit the National Renewable Energy Laboratories' Web site to see the Wind Energy Atlas and assess the wind resources in your area. Also, keep in mind that other nearby structures can block or affect the wind reaching the system.


  1. Zoning limitations. A good rule of thumb is that wind turbines should be sited on at least 1 acre of land, but this might be affected by local zoning limitations for structures over 35 feet high. Variances are often needed to site a tall structure, and they often depend on the surrounding area and setbacks. The table below shows the zoning requirements for Montgomery County. You can obtain more information through Montgomery County's Department of Permitting Services.


Restrictions on Wind Energy Installments
  Lot Class Lot Size (min. sq ft) Max. Building Height (ft) Max. Building Height-
with Plan Approval (ft)
Max. Accessory Structure Height (ft) Street Line Setback (ft) Rear Line Setback (ft) Side Line Setback (ft) National/ Historic Park Setback (ft)
  R-60** 6,000 35 40 15 60 5 5  
  R-90** 9,000 35 40 15 60 5 5  
Rural Zones R-200* 20,000 50 50 50 65 7 12  
RE-1* 40,000 50 50 50 80 10 15 200
RE-2C* 87,120 50 50 50 80 10 15 200
RE-2* 87,120 50 50 50 80 10 15 200

*If in a rural NC (Neighborhood Center) then the accessory strucutre height is max. 35 feet.
**Any accessory building or structure in these zones with a height greater than 15 feet, the side yard and rear yard minimum setback must be increased from the requirements at a ratio of 2 feet of additional setback for each foot of height in excess of 15 feet.


  1. Community-specific limitations. Small wind systems are not appropriate for dense urban areas. It's also a good idea to communicate with the surrounding community to educate them on the project and how it might affect them and their property before committing to an installation. Sample letters are available on the American Wind Energy Association's (AWEA) Web site.


  1. Image of a wind turbine.How much electricity can be generated. The amount of electricity generated per month depends on the system size and the consistency and velocity of the wind. The U.S. Department of Energy's Small Wind Electric Systems Guide suggests that a 1.5-kilowatt system (costing about $7,000) can generate 300 kilowatt-hours of electricity a month in an area with a 14 mph average annual wind speed. A larger system can generate more electricity.


  1. The estimated payback. The cost of a small wind energy system (3 to 10 kilowatts) with an 80-foot tower and necessary electronics ranges from $15,000 to $50,000. Like solar, the payback period for this investment varies and is also dependent on available incentives. A list of available incentives is provided below.

Selecting and Finding a Service and Product Provider

Installing a wind turbine is different than installing a solar or geothermal system. Rather than contractor installations, wind turbine manufacturers often offer installation services as part of the package of purchasing a wind turbine system. The Maryland Energy Administration also hosts a list of installers in Maryland.

When shopping for an installer always check for relevant licenses, request references and a list of itemized costs, and get multiple quotes.


Additional Resources and Incentives for Wind Energy

Learn more about:


Geothermal Energy 

Although geothermal heating and cooling systems don't generate electricity, they do help reduce the need to use electricity, natural gas, or heating oil to heat or cool a building. GeoExchange systems use the constant temperature below the earth's surface to help the heating and cooling process, a process that is considerably more efficient than systems that use outside air as a heat source or sink.

Think about it:

On a cold winter day (30 °F), standard heating systems (such as a heatpump) need to heat cold outdoor air by 40°F or more before it is used to warm a building. On a hot summer day (95 °F), air conditioners need to cool the air considerably before it is circulated. Geothermal systems, on the other hand, raise (in winter) or lower (in summer) the temperature of the air or water used to heat or cool a building to approximately 55 °F (the temperature below the earth's surface). This reduces the amount of energy needed to bring indoor temperatures to a comfortable level.

Overall, geothermal systems save users 30 to 60 percent in energy costs compared to conventional heating or cooling systems. They often pay for themselves in 5 to 10 years.


Is a GeoExchange System Right for Me?

Geothermal systems aren't obtrusive, so they can be great options for buildings where aesthetics are a concern or where zoning regulations prohibit installing other renewable energy systems. (However, it is necessary to drill wells or trenches to lay the geo-energy exchange loop, so there is some outdoor disurbance during installation.)

Also, geothermal systems require only limited maintenance, and they are quieter and last longer than air-source heat pumps. The system life is often rated at 25 years; the ground loops are good for at least 50 years.

Geothermal systems can be designed in a variety of ways to meet your needs and can often be integrated with existing equipment. The design and size of a geothermal system directly affect its cost, so it's necessary to seek the advice of a qualified designer or installer to estimate the cost and savings potential of installing a system.

Residential Geothermal Systems
Diagram showing a residential GeoExchange System in heating mode.
Diagram showing a residential GeoExchange System in cooling mode.

The diagrams above show the pattern of heat exchange in a residential geothermal system in both heating (left) and cooling (right) modes. Click on either image to see a larger image. Source:


Diagram showing a vertical closed-loop geothermal system
Vertical closed-loop geothermal systems can be used to heat and cool large office buildings.

Selecting and Finding a Service and Product Provider

When shopping for a geothermal system installer, always check for relevant licenses, request references and a list of itemized costs, and get multiple quotes. Additional qualifications to inquire about include the International Geothermal Heatpump Association (IGSHPA) accredation. The following sites include lists of qualitifed providers:


Additional Resources and Incentives for Geothermal Technologies

​Learn more about: