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Solar Photovoltaic

What It Is

Photovoltaic energy – often referred to as PV – is the active technology that produces electricity from solar radiation.  Silicon crystals are arranged on a flat panel and generate 0.5 to 0.6 volts of direct current (VDC) when exposed to the sun.  These solar cells are wired together so their combined output is 12 VDC from what is called a photovoltaic module, the basic building block of a PV system.

How It Works

The amount of electrical energy generated varies throughout the day depending on weather conditions, the angle of the solar radiation in relation to the module, and where the installation is located.  Modules of different brands can be compared by ratings that combine the size (surface area) of the panel, efficiency, and a set of standardized conditions that calculates the duration of time of peak generation in an average day.  Typically, a properly placed module will produce about 150 to 225 Watts per day.

System components and applicability vary depending on how the energy is used:

• Simultaneous Generation and Consumption - is the simplest and cheapest but requires that energy be used when generated.  Electricity that is generated but not used is wasted.
• Grid tied with a net meter - allows a system to sell any electricity generated beyond the buildings needs back to the power grid.  Here the meter will run backwards at a prescribed rate, reducing the electricity bill for the system owner.
• Off the Grid with storage - allows a non grid tied system to store generated electricity that is not immediately used.  The method of storage can be batteries, fuel cells etc.  This is useful in remote areas where it can be prohibitively expensive to wire a building into an established electrical grid.

A complete PV system design is based on the size and type of the building electricity demand.  Other necessary components include a charge controller that maintains a consistent voltage, diodes and shut-offs to isolate and protect components in the system and an inverter if the appliances require alternating current (AC).  When more than one PV module is required, they can be arranged into a PV array, connected in series or parallel to achieve a desired voltage output.

• Solar Photovoltaic & Thermal Systems (PV/T) - Solar thermal systems provide perfect racking on which to place solar photovoltaic (PV) panels allowing a client to benefit by collecting both free heat and electricity from the sun.  Solar PV/T systems act symbiotically to improve on the weaknesses of traditional PV systems (at peak sun exposure PV solar modules tend to overheat, losing efficiency) even as they collect heat.  By having a solar thermal system underneath, the PV panels maintain a lower, more even temperature increasing their collection efficiency.  This contributes to a significantly better ROI, and allows efficient solar energy use on any building.

Benefits

• PV technology is mature, robust and reliable, has no moving parts, and requires minimal maintenance.
• Reduces pollution & greenhouse gases because no fossil fuels power the system
• Grid-tied systems are relatively quick and easy to install
• Modular systems are easily scalable to fit any size of demand
• Systems add to the value of the building to which they are installed and mitigates the risk of utility price increases for electricity
• Your company can receive positive publicity as a responsible corporate citizen by employing a renewable energy system