Solar Fundamentals

A variety of technologies convert sunlight to usable energy for buildings. The most commonly used solar technologies for homes and businesses are solar water heating, passive solar design for space heating and cooling, and solar photovoltaics for electricity.

Solar cells, also called photovoltaic (PV) cells, convert sunlight directly into electricity. PV gets its name from the process of converting light (photons) to electricity (voltage), which is called the PV effect.

The PV effect was discovered in 1954, when scientists at Bell Telephone discovered that silicon created an electric charge when exposed to sunlight. Soon solar cells were being used to power space satellites and smaller items like calculators and watches.

Traditional solar cells are made from silicon, are usually flat-plate, and generally are the most efficient.

Energy 101: Solar PV from U.S. Department of Energy

Conventional fuels have real social, environmental, and economic impacts. There are annual and cumulative costs that stem from all of the pollutants (airborne, solid, and liquid) emitted from mining, processing, and transporting fossil fuels that impact our public health and the environment. Electricity derived from coal and natural gas will never be able to outweigh the energy and continual resources required to produce it. Unlike conventional energy sources, PV systems produce clean electricity for decades after achieving their energy payback in three or fewer years—this is truly the magic of PV technology.

Although a PV array produces power when exposed to sunlight, a number of other components are required to properly conduct, control, convert, distribute, and (sometimes) store the energy produced by the array.

Depending on the functional and operational requirements of the system, the specific components required may include a DC-AC power inverter, battery bank, system and battery controller, auxiliary energy sources and sometimes the specified electrical load (appliances). In addition, an assortment of balance of system (BOS) hardware, including wiring, overcurrent, surge protection and disconnect devices, and other power processing equipment.

Equipment

Photovoltaic (PV) cells

Most PV cells fall into one of two basic categories: crystalline silicon or thin-film. Crystalline silicon modules can be fashioned from either monocrystalline, multicrystalline, or ribbon silicon. Thin-film is a term encompassing a range of different technologies, Thin-film technology generates a lot of the current R&D chatter, but crystalline modules currently capture more than 80% of the marketplace.

Inverter

A solar inverter is the electrical box used to turn direct current (DC) electricity produced by the solar panes into the alternating current (AC) electricity that you use in your home.

There are three main inverter options available for homes residential and commercial solar installations: string inverters, microinverters and power optimizers.

String inverters are the least expensive and best used with installations where there is very little shading and long straight runs for arrays.

Microinverters and power optimizers are typically more expensive but also more efficient. They are best suited for unavoidable shade installations or where panels are installed on multiple planes and/or facing different directions.

Grid-tied inverters allow the extra AC electricity produced by your array back into t he grid to help spin your meter backwards (Net Metering).

Mounting equipment

Rack mount: A metal framework specially designed to allow easy attachment and detachment of the panels. The panels are almost always parallel to the roof surface. A wide range of different types of racks are available.

Ground-mounted systems: If you have enough space available, you can mount your panels in a specially engineered rack structure affixed to the ground. In other cases, roofs are simply too complex, with too many vents and odd angles, to support a large array of solar panels, so ground mount may be the only option.

Disconnect switches

Disconnect switches are used to disconnect the power being produced by your array. A solar PV system typically has two safety disconnects. The first is the PV disconnect (or Array DC Disconnect). The PV disconnect allows the DC current between the modules (source) to be interrupted before reaching the inverter.

The second disconnect is the AC Disconnect. The AC Disconnect is used to separate the inverter from the electrical grid.

Power Meters

Utility power meters: Conventional power meters are capable of spinning backward, but utility companies usually change to a special digital meter when you connect to the grid because most solar customers go to the TOU (time-of-use) rate structure, which requires more intelligent processing than a mechanical device is capable of.

Technology

Technology

We utilize some of the most advanced software applications ranging from project management, CAD, solar irradiance analysis, world weather patterns, public and private data sets and robust financial and performance algorithms.

Up until a few years ago many of the systems and software we use today were only available to government sectors, utilities, and the largest of private corporations. As costs have come down and technology advanced, the field is becoming leveled allowing home and small business owners access to the same cost savings and revenue opportunities by going solar.

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