Solar

Solar energy is Maryland’s largest energy resource. It is a critical piece of the solution to Maryland’s energy supply puzzle - it is available everywhere in the state, can be readily deployed, and can be easily added to our existing energy system without the need for expensive transmission lines or lengthy environmental impact hearings. We can place solar energy where it is needed most - on stressed or over-loaded zones of our electric grid.

How It Works

Solar energy is one of the oldest and most reliable natural resources we have. Capturing the sun’s energy allows us to heat water or air for various applications and convert solar energy into electricity.

Solar Thermal

Solar thermal is the conversion of solar energy from radiation to heater thermal energy. Sunlight strikes an object and radiant energy is converted to heat, warming the object from the sun’s energy.

• Active Solar: Delivers thermal energy from the point of collection to the point of use, such as the use of electric blowers to circulate air or pumps that transfer hot water.
• Passive Solar: Delivers solar energy to the point of storage or use directly, without requiring the use of pumps or fans. Passive solar design involves orienting a building so that it absorbs its heating requirements and stores some heat in the building materials. Passive solar techniques include the use of thermal masonry walls, vertical solar chimneys and movable insulation.
• Concentrated Solar Power: Uses mirrors - called Heliostats - to concentrate the sun’s energy onto a focal point to raise temperature. This is traditionally used for solar thermal power applications, and typically in sunny, arid regions.

The summer sun in Maryland generates more energy in 1 day than our power plants could produce in 1 year.

Solar Electrical

Solar electrical is the direct conversion of solar energy radiation into electrical energy, creating a voltage and current to deliver power. Solar electrical systems typically use photovoltaic (PV) cells or modules to capture the sun’s energy. PV modules are typically assembled into arrays that are mounted on a building or on the ground.

PV systems capture energy and then its modules transform it into direct current (DC). An inverter can converted DC to alternating current (AC). These inverters can send power either to the local grid or to an independent system. Very little power is sacrificed in the conversion of DC to AC power with modern inverters.

Ground solar systems can produce energy for a dedicated load, or they can feed an electrical system to which a load is connected. The solar arrays can be fixed in a single position, or they can track the sun as it moves from east to west or north to south, which is one axis tracking, or both, which is two axis tracking. The tracking systems keep the modules pointing at the sun for more hours during the day so that they can capture more energy with the same number of modules.

PV modules may also be built into building materials like roofing shingles or siding products. New thin-film PV technologies use very thin (2 microns) coatings of active material deposited on glass and sandwiched between two glass sheets.  Thin-films can be layered together and coated on other materials.

Distributed Solar Thermal Technology

This solar technology is primarily used for domestic water heating, pool heating, and space heating.  Solar water heating is the most widely used distributed solar technology in the world today.  Although invented in the US (Baltimore, 1891), this mature technology is largely used elsewhere, leaving less than one-half percent of the world’s solar water heating generation in the US (2008 data).

The primary components of a typical residential solar water heating system consist of one or two panels, a solar water heater tank with a heat exchanger , a small system controller and circulator pump – known as the pump control module, some insulated piping, and a nontoxic antifreeze for the heat transfer fluid.  All systems include some form of back-up energy but electric back-up is the most common and will allow for a single water tank. 

Solar water heaters can also be used to heat swimming pools and spas. In most pool heating systems, the existing pool filtration system pumps the pool water through the solar pool heating collectors.  These are relatively inexpensive, durable, specially formed plastic material.  These systems are highly efficient at the low temperatures required for pool heating.  The water is directed to the collectors by means of a basic differential temperature controller.

When properly sized, systems in Maryland can extend the swimming season several months and increase water temperatures up to 10 degrees or more.  Most pools require total solar collector area on the order of 50-75% of the pool’s surface area.  If this much roof space is not available, then ground mounts are often an alternative. Systems are low maintenance and typically last for more than 25 years. Although there are currently no special incentives for pool heating, the paybacks are generally in the 2-4 year range when comparing to traditional heating methods.

Active solar space heating can be accomplished with similar systems as solar water heating and the systems are often integrated to accomplish both purposes, with water heating being the primary load.  Space heating does require more extensive expertise to design and install.  Consideration must also be given to various types of heat delivery systems (radiant floor is best) as well as heat dissipation in the off season.  This can be accomplished with heat dissipation systems, drain-back systems, or alternative loads like pools or spas.

Solar in Maryland

Solar energy already generates over 3,000 kilowatts of power in Maryland.

• Maryland’s existing roof area is sufficient to generate approximately one-fourth of  our electricity demand from solar systems. Maryland typically averages 4.5 peak hours of sunlight per day per year - which translates into 1200 kilowatt hours of power in a year with a 1,000 kilowatt solar system.

Augmenting coal generation with solar power would reduce carbon dioxide emissions and other pollutants such as mercury, sulfur dioxide, and nitrogen oxides.

• Solar energy generation coincides largely with peak daytime energy demand, which is typically met by gas - fired combustion turbines. Combustion turbines may be cleaner that coal but they still produce thousands of tons of carbon dioxide.

Solar is a growing source of jobs in Maryland - more than 1,200 professionals are employed by the solar industry in Maryland.

• Leading firms such as BP Solar, groSolar, SolarCity and SunEdison all have major operations in Maryland. Standard Solar was founded and operates is headquarters in Maryland. Many new electrical and plumbing contractors that are offering solar technologies as part of their product line are also based in Maryland.

Upcoming Legislation.

• The need for longer term purchase agreements for the acquisition of the Solar Renewable Energy Credits, or SRECs.