Photovoltaic (PV) Systems

What are Photovoltaic (PV) Systems?

Photovoltaic (PV) systems are semiconductor devices that use renewable solar energy to create electricity.[1] PV cells placed together in a module which are then grouped to form an array applied to surfaces such as roofs or applied as ground mounts. A specific PV system, known as Building-Integrated Photovoltaic (BIPV) uses PV technology and applies it to building materials, serving multifunctional purposes. [2] For example, a BIPV skylight not only captures energy to generate electricity for a building but also provides daylighting (see Daylighting). Another strategy incorporates PV technology into an exterior wall for decorative purposes as well as collecting energy.

PV systems can be stand-alone or grid-connected. Stand-alone systems, not connected to the electricity grid, are used in remote locations where extending power lines can be expensive costing anywhere from $15,000 to $50,000 per mile.[3] These systems can also be used by people who live near the grid who wish to be independent of the utility or invest fully in non-polluting energy resources.

Grid-connected systems utilize solar energy when available and feed excess electricity back to the grid. When the sun does not shine, the grid supplies the home electricity.[4] A grid-connected PV system consists of one or more PV modules are connected to an inverter, which converts the system’s direct-current (DC) electricity to alternating current (AC). Optional batteries provide energy storage or backup power in case of a grid power interruption or outage (see Energy Storage and Backup Power Generation).[5]

Connecting to the grid requires typically requires two agreements, an interconnection agreement and a purchase and sale agreement.[6] Net-metering allows excess electricity generated by grid-connected PV systems to feed back to the grid.  Net-metering rules vary from state to state and may restrict the amount of energy exported back to the grid based on a minimum capacity that is established by the utility or utility commissions. If the home uses more electricity than is produced by the PV system, the system owner pays the power provider for the difference between what was used and produced.[7] When a customer’s renewable energy system produces more electricity than the customer needs, the excess energy is exported back to the grid.  All grid connected PV systems qualify to generate Solar Renewable Energy Credits (SRECS) which could be traded for additional incentives.[8]

How to Implement a Photovoltaic (PV) System

Check out Google Project Sunroof and enter your address to find out the solar savings potential of your home.

Contact the NJ Office of Clean Energy to learn about current programs, tools, and available funding for Photovoltaic Systems.

While projects can tailor PV systems to meet the needs of a particular site and home, south facing surfaces not shaded by nearby trees, buildings, and structures provide the best results (see Building Orientation). If possible, orient collectors at the angle of the location’s latitude (in New Jersey, this is approximately 40°N). Flat roofs also work well for solar electric systems, allowing PV modules to tilt at an optimal angle toward the sun. Ground systems mounted on a tracker to follow the sun work well for homes with large yards.

Hire a professional, licensed contractor to design and install the photovoltaic system, and help with paperwork for any tax credits and rebates or other incentives.[9]

Example

New Jersey Clean Energy Program PV Installation, Suburban Home, NJ.

This case study describes a New Jersey resident’s experience installing solar panels on his home.

• An NJ Clean Energy Program rebate reduced the initial cost by $11,000
• Electric bills dropped by 25 percent each month
• Ten-year payback based on estimated annual energy savings.

Benefits

Incorporating on-site renewable energy systems reduces greenhouse gas emissions,

protects against the fluctuating costs of fossil fuels and saves on purchasing energy from utility companies while providing additional ecological and user benefits. The modularity of PV systems allows great flexibility in applying this technology to different home designs. Solar PV can help manage peak demand and lower utility rates, while also providing shade and urban heat island reduction benefits (see Demand Response and Peak Load Management). Additional benefits include low-cost operations and maintenance, and US-based manufacturers and installers that provide domestic jobs.[10]

Costs

PV systems require a high upfront investment but lower monthly electricity bills. Most solar electric systems last 30 years and pay for themselves in 4 to 5 years.[11] The cost per kilowatt-hour goes down as the system size increases. In 2019, residential solar electric systems incurred a median installed cost of $2.50 – 3.00 per watt. Federal and state tax credits and rebates are available to offset costs. While actual costs vary depending on system configuration and other factors, the following are average costs before rebates and taxes:

• A 2-kilowatt (2,000-watt) system costs between $5,000 and $15,000 and supplies enough energy to meet most of the needs of an energy-efficient home.

• A 5-kilowatt system may be installed for $10,000 to $40,000, with an average cost of around $20,000, and can meet all the electricity needs of a large home.[12]

Resiliency

Solar PV systems support energy resiliency in many ways. PV systems with islanding capability and battery storage can operate independently from the grid during outages or at times of system peak and increase grid reliability by managing system outages and peak demand (see Solar Islanding and Microgrid-Ready Solar PV and Energy Storage and Backup Power Generation). Solar islanding and microgrid ready PV systems support the smart grid, which aims to diversify and strengthen the electric grid through better energy management and the integration of cleaner energy sources such as wind and solar as well as electric vehicle charging and energy storage. PV systems installed high up on buildings or poles are protected from flood waters. PV systems that meet local codes and wind loading requirements are designed to withstand damage and provide a reliable source of power in hurricane zones.[13] Separation from the electricity grid also offers protection from security threats.

[1] E. Hotchkiss, I. Metzger, J. Salasovich, and P. Schwabe. 2013 Alternative Energy Generation Opportunities in Critical Infrastructure New Jersey. Produced under the direction of the U.S. Federal Emergency Management Agency by the National Renewable Energy Laboratory (NREL) https://www.nrel.gov/docs/fy14osti/60631.pdf (accessed Oct 3, 2018).

[2] Eiffert Ph. D, Patrina, and Gregory J. Kiss. NREL. Building-Integrated Photovoltaic Designs for Commercial and Institutional Structures: A Sourcebook for Architects.” www.nrel.gov/docs/fy00osti/25272.pdf (accessed  April 5, 2018).

[3] US DOE. Off-Grid or Standalone renewable Energy Systems. https://www.energy.gov/energysaver/grid-or-stand-alone-renewable-energy-systems (accessed April 10, 2018).

[4] NREL. Connecting Your Solar Electric System to the Utility Grid. https://www.nrel.gov/docs/fy02osti/31687.pdf (accessed April 10, 2018).

[5] US DOE. A Consumer’s Guide: Get Your Power from the Sun. http://www.nrel.gov/docs/fy04osti/35297.pdf (accessed April 10, 2018).

[6] US DOE. A Consumer’s Guide: Get Your Power from the Sun. http://www.nrel.gov/docs/fy04osti/35297.pdf (accessed April 10, 2018).

[7] NREL. Connecting Your Solar Electric System to the Utility Grid https://www.nrel.gov/docs/fy02osti/31687.pdf  (accessed April 10, 2018).

[8]  NJ’s Clean Energy Program. Net Metering and Interconnection. http://www.njcleanenergy.com/renewable-energy/programs/net-metering-and-interconnection (accessed April 10, 2018).

[9] US Department of Energy. “A Consumer’s Guide: Get Your Power from the Sun.” http://www.nrel.gov/docs/fy04osti/35297.pdf (accessed April 5, 2018).

[10] Renewable Energy World. Advantages and disadvantages of Solar Photovoltaic – Quick Pros and Cons of Solar PV http://www.renewableenergyworld.com/ugc/articles/2012/12/advantages-and-disadvantages-of-solar-photovoltaic–quick-pros-and-cons-of-solar-pv.html (accessed April 5, 2018).

[11] Ibid.

[12] Ibid.

[13] E. Hotchkiss, I. Metzger, J. Salasovich, and P. Schwabe. 2013 Alternative Energy Generation Opportunities in Critical Infrastructure New Jersey. Produced under the direction of the U.S. Federal Emergency Management Agency by the National Renewable Energy Laboratory (NREL) https://www.nrel.gov/docs/fy14osti/60631.pdf (accessed Oct 3, 2018).