Solar FAQ's

How Solar works

A typical silcon PV cell is composed of a thin wafer consisting of an ultra-thin layer of phosphorus doped (N-type) silcon on top of a thicker layer of boron doped (P-type) silcon.  An electrical field is created near the top surface of the cell where these two materials are in contact, called the P-N junction.  When sunlight strikes the surface of a PV cell, this electrical field provides momentum and direction to light stimulated electrons, resulting in a flow of current when the solar cell is connected to an electrical load.

Regardless of size, a typical silcon PV cell produces about 0.5 - 0.6 volts DC under open circuit, no-load conditions.  The current (and power) output of a PV cell depends on its efficiency and size (surface area), and is proportional to the intensity of sunlight striking the surface of the cell.  For example, under peak sunlight conditions a typical commercial PV cell with a surface area of 160 cm2 (~25 in2) will produce about 2 watts peak power.  If the sunlight intensity were 40 percent of peak, this cell would produce about 0.8 watts. 

The Comonents of a PV Array

There are three different levels of a photovoltaic (PV) array.  A PV module is actually made up of interconnected smaller photovoltaic cells, which are typically rated at 1-2 watts.  These PC modules or panels, which ae made of PV cells, can be interconnected with more modules to produce what is called a solar array.  A racking system attaches the solar array to the roof of a building or house.  On a pitched roof, a flush mount is installed.  If the roof is flat with no pitch, a ballasted system is typically used.  There are also ground mounted arrays as well as pole mounted arrays.

The ideal orientation for a solar array is south facing.  This helps maximize the amount of light captured throughout the year without having to reorient the entire array.  Solar arrays can be installed on east and west facing roofs as well.  It should be noted that there will be some amount of energy harvest loss with solar arrays that face east or west an energy harvest estimate can better assess energy output.  The pitch of the array is dependent of the pitch of the roof.  Another important factor in assessing array location is shading.  There should not be any shading over asolar aray, as this will reduce electric production as well as harm the solar modules

Balance of System

A solar array is only one of many components that make up a solar system.  The rest of the system is called the Balance of System.  The balance of system includes all of the other components of the solar installation. This includes all of the wiring and conduit, the inverter, disconnects, breaker box, and PV and electric meters.

Conduit & Wiring: The conduit contains the wires that connect the solar array tothe rest of the components.

Inverter: A solar array produces direct current (DC) electricity wich cannot be used by common appliances as most are designed to run on alternating current (AC).  An inverter is used to convert the DC power from the solar array into AC power, so the electricity is compatible with all of the appliances in a household or building.  A typical inverter is about 95% efficient.

Disconnect: Switch used to shut-off the flow of electricity.

Breaker Box:  Houses all of circuit breakers.