Solar Roofing Definitions & Terms

Annual Solar Savings: The annual solar savings of a solar building is the energy savings attributable to a solar feature relative to the energy requirements of a non-solar building. In other words, compare what you save with solar vs. not having solar.

Array: An interconnected system of PV modules that function as a single electricity-producing unit. The modules are assembled as discrete structures with standard support or mounting. In smaller systems, an array can consist of a single module.

Azimuth Angle: The angle between the true-south and the point on the horizon directly below the sun. This term is used to describe the direction of your solar panels.

Balance of System (BOS): The ratio of system (BOS) encompasses all components of a photovoltaic system other than the solar panels. This includes wiring, switches, service panel, combiners, a mounting system, one or many solar inverters, and more.

Ballast Mount: Most solar mounts are attached directly to a home’s rafters, while a ballasted mount is used to install solar panels on flat roofs using weights to keep the array in place. No penetration of the roof is required.

Battery life: The number of charging and discharging cycles a battery is expected to have.

Battery/Energy Storage: A device to enable energy storage in a chemical form, which can later be drawn on to supply power. While batteries are not a requirement to go solar, they can be an excellent option for anyone concerned about power outrages or backup power. Batteries CAN be integrated later, even if your solar panels have already been installed.

Capacity: The amount of energy a battery can store measured in kilowatt-hours.

Depth Of Discharge (DoD): The DoD refers to the battery capacity used. Most batteries for solar have a guaranteed depth of discharge they will allow within the warrantied output.

Dollars Per Kilowatt Hour: Because power warranties on solar panels vary drastically due to guaranteed degradation, the most accurate way to determine the cost of solar is to look at how much the energy costs to produce (the same way you pay the utility company). To do this, you look at how much energy the system will have over the warranty period (30 years) divided by the cost of the solar energy system.

Dollars Per Watt: People often calculate the average cost of solar panels by looking at their expenses in dollars per watt. This is done by dividing the system cost by the number of watts the solar panel’s nameplate rating shows. However, your system will not always produce its nameplate rating due to degradation and many other factors, so a better way to value the actual cost of solar is to look at dollars per kilowatt hour ($/kWh) over the warranty period.

Efficiency: The portion of energy in the form of sunlight that can be converted from a solar panel into electricity. The higher the efficiency, the more usable power you can get from your solar panel. Make sure your solar installer uses high-efficiency solar panels for your home.

Electricity Grid: The electricity grid is the system that delivers electricity from power generators to power users. For the owner of a solar power system, the grid can, in effect, be an energy storage device since you are sending excess power into it when your solar power system is producing electricity, and you can draw electricity from the grid when your solar power system is not producing.

Fixed Tilt: A photovoltaic array set in at a fixed angle with respect to horizontal.

Grid-Connected System: A solar electric or photovoltaic (PV) system in which the PV array acts like a central generating plant, supplying power to the grid.

Interconnection: The linkage of transmission lines between two utilities or between a utility and an end-user, enabling power to be moved in either direction. This is required to have your solar system connected to the local utility grid.

Inverters: Inverters are equipment that converts the type of electricity generated by the solar panels’ direct current (DC) into electricity that can be used in your home–alternating current– (AC). Modern inverters prevent electricity from flowing back to the electrical grid should the local grid go down. This rapid shutdown without exporting energy to the grid is known as anti-islanding. This is a required feature designed to protect workers repairing the power grid.

Kilowatt-Hour (KWh): A measure of electrical energy equivalent to the power consumption of 1,000 watts for one hour.

Lithium Ion/ Lithium Iron Phosphate (LiFePO 4) Battery: A battery technology that uses one of several possible compositions of lithium ion or lithium iron chemical to store energy. This technology is the most popular for solar applications because lithium-ion batteries are compact and offer the most extended lifespan at a reasonable cost.

Meter: A meter designed to measure the electricity you use but can also measure the power you produce and supply to the electricity grid. This digital meter that tracks inward and outward flows allows your local utility to give you credit for the electricity you supply to the power grid.

Micro-Inverter: A micro-inverter system has multiple inverters (one for each solar panel). In conventional inverter systems, the whole system goes out when one panel fails. Or when one panel’s output drops (thanks to fallen leaves, a passing cloud, or some other unavoidable factor), the system’s overall performance declines to match that lowest-performing panel. With microinverters, each panel operates independently!

Monitoring Systems: Devices or applications provide details about solar power and energy storage systems. Data may include energy usage, a display of the amount of stored energy remaining stored, and information on the electricity supply cost at different times of the day.

NABCEP^® (North American Board of Certified Energy Practitioners: The North American Board of Certified Energy Practitioners^® (NABCEP^®) is the most respected, well-established, and widely recognized national certification organization for professionals in the field of renewable energy. It is a voluntary certification that a solar installer or solar sales representative may receive after extensive testing. This is the gold standard for hiring a solar energy company.

Net Metering: Net metering is a solar program in some states that provides credits to you for supplying excess electricity from your solar power system into the grid. Typically, you receive a credit for any extra solar energy that can be used later — think “rollover minutes,” but with solar power! Depending on your utility company, the terms of Net Metering may vary.

Peak Sun Hours: The equivalent number of hours per day when solar irradiance averages 1,000 w/m2.

Photovoltaic (PV) panels: These are solar panels that take sunlight (photons) and, using specially designed material (commonly, silicon), create electricity (voltage) that can be used or stored.

Renewable Energy Certificates: Also known as RECs, Renewable Energy Credits, Green Tags, green energy certificates, or tradable renewable certificates, are tradable commodities that prove one megawatt-hour of electricity was generated from a renewable energy source. One megawatt-hour equals 1,000 kilowatt-hours, and the average residential customer consumes about 800 kilowatt-hours a month. Many utility companies are not currently buying RECs (or are buying them at a low price that doesn’t cover the application cost).

Solar ITC / Inflation Reduction Act: As a homeowner, you can apply for credit when filing your income taxes under the Solar Investment Tax Credit. This Federal tax credit is used when a solar system is purchased outright (or with financing) and installed in your home. Consider consulting your tax advisor to determine if it currently applies to California.

Solar Panels: Also known as Photovoltaic (PV) panels, solar panels take sunlight (photons) and, using specially designed material (commonly, silicon), create electricity (voltage) that can be used or stored.

Solar Panel Power/Performance Warranty: The amount of electricity a solar panel produces declines by a tiny % every year, known as degradation. That’s true of all solar panels but to varying degrees. A power/performance warranty is the manufacturer’s guarantee that the panels will not lose more than the designated % of power output capacity over time. To ensure the best return on investment and long-term value, look for solar panels with higher output warranties (lower degradation rates).

Solar Panels Product/Equipment Warranty: A solar panel’s product warranty covers the integrity of the panel itself and protects you against problems such as manufacturing defects, environmental issues, premature wear, and tear, etc. The terms and conditions of the solar product warranty can change dramatically. On top of that, an additional limited warranty (extended warranty) may be available. As with most warranties, a more extended period is generally more advantageous to you.

Watt And Kilowatt (KW): A watt is a power unit. A kilowatt is 1000 watts.