Power Generation, Transmission, and Use

Markets, Regulation, and Oversight

Impacts of Power Generation and Transmission

Looking Ahead


CEIR Report Map


Maryland Power Plants and the Environment (CEIR-18)

2.1.3 Distributed Generation

Click to OpenDistributed Solar GenerationDistributed generation (DG) refers to those generating resources located close to, or on the same site as, the facility using power. It is typically installed on the customer side of the meter and used to serve on-site power needs; because of this, distributed generators are not centrally dispatched by the regional grid operator. Types of DG technologies include internal combustion engines, small wind, solar, small hydroelectric, micro gas turbines, and fuel cells. Some of these technologies can be used to provide electricity to the grid during times of peak demand. The majority of DG units are diesel-fired emergency backup generators. However, an increasing share of this capacity comes from solar energy, which is predominantly grid-tied for the purposes of net-metering and generating solar renewable energy credits (RECs) for sale or trade (see Section 5.1.1 for discussion on RECs).

On-site generators with a capacity of 2 MW or less are not required to obtain a Certificate of Public Convenience and Necessity (CPCN) or apply for a CPCN waiver (or exemption). In addition, certain generators of up to 70 MW in capacity are eligible to seek a CPCN exemption:

The Maryland PSC requires an applicant seeking a CPCN exemption to identify its facility as one of four specific types:

It is difficult to accurately estimate the total amount of DG in Maryland as systems smaller than 2 MW are not required to obtain a CPCN exemption. The vast majority of solar DG systems fall into this category.

As of the end of 2015, about 1,637 MW of generation capacity had been granted CPCN exemptions in Maryland, including 62 MW of solar capacity and 250 MW of land-based wind power. According to the 2015 PSC report on net metering, 236 MW of solar DG and 1.2 MW of small wind facilities had been installed in Maryland by mid-2015 under net-metering arrangements.

DG units are often used to provide emergency backup power in the event that large and essential loads, such as government offices, hospitals, colleges and universities, commercial and industrial facilities, telecommunications installations, and farming operations, lose electricity service. By fuel type, Maryland’s distributed generators (see Figure 2-5) are mostly fossil-fueled, consistent with their use for backup power. An increasing, but still small, share of DG capacity is solar, which is predominantly grid-tied for purposes of net-metering and generating solar RECs for sale or trade. Between June 2014 and June 2015, for example, statewide net-metered solar system capacity increased 66 percent. The solar energy requirement in the Maryland Renewable Energy Portfolio Standard (RPS) will also continue to provide an incentive to add distributed solar generation to the Maryland grid.

Figure 2-5 Distributed Generation by Fuel Type (as of 2015)

Figure 2-5 - pie chart of Distributed Generation by Fuel Type, Petroleum 61%, Solar 16%, Wind 13%, Natural Gas 8%, Biomass 2%

Source: PSC CPCN Database and Maryland Public Service Commission, “Report on the Status of Net Energy Metering in the State of Maryland,” January 2016, (Download Adobe Acrobat Reader).

Note: This figure only includes solar from net-metered systems and CPCN-exempted systems.

MW is equal to 2 million watts, enough power to meet the simultaneous peak demand of about 500 homes.
The generating capacity of a power plant is the maximum amount of power it can instantaneously supply to the grid and is measured in megawatts (MW). Electricity generation is the amount of power supplied through time (energy) and is measured in megawatt-hours (MWh).
Constellation Energy Group merged with Exelon Corporation on March 12, 2012
Through a joint venture with Électricité de France (EDF) called Constellation Nuclear Energy Group, Constellation Energy (which merged with Exelon Corporation) owns 50.1 percent of the Calvert Cliffs nuclear facility.
GenOn Energy, Inc. merged with NRG Energy, Inc. on December 14, 2012.

Distributed Solar Generation

Distributed solar generation has played an increasing role in Maryland as a source of total generation. The increasing use of solar rooftop photovoltaic (PV) in Maryland is largely attributable to Maryland’s Renewable Portfolio Standard (RPS) and a 30 percent federal tax credit.

BP Solar Millennia Modules - As part of a major home improvement project, Lynne Gillette and Lynn Feldman, of Glenn Dale, Maryland, installed a ~1.35 kW amorphous silicon, thin film PV system on their roof. Apex, Silicon-Film (trademark) SunUPS System; 4.8 kW rated peak array capacity; Belmont, California - House with PV panels mounted on the roof. The system is grid connected and has battery back-up.

FERC issued Order No. 792 in November 2013 that amends its existing rule on small generator interconnection agreements and procedures. The regulatory reforms are intended to streamline the grid interconnection process for solar projects that meet certain technical standards.