Ever wonder how those big solar panel arrays work up on people’s roof or in the yard?  Wonder no more – here’s a thumbnail of how most of these systems, known as Photovoltaic (or “PV” more commonly) Grid-Tie Systems, work.  We’re seeing more and more solar systems in Lancaster County, PA these days.

First off, these solar systems generate electricity – don’t confuse them with what’s called “Solar Thermal” systems (we’ll get to those in another article).   There are several main components of a solar grid-tie system:

1) The panels – known as an “array”.  These units are constructed from silicon resins and metal to collect the sun’s rays and cause the reaction within the panel that creates an electric current.  They are commonly called “collectors” for obvious reasons…  By the way, the current generated is Direct Current (DC).  Wires transmit the current from the collectors to the next component in the system, known as an Inverter.

2) The Inverter – usually wall-mounted in a protected location such as the basement, garage, etc.   This component converts the DC power from the solar panels into AC (Alternating Current) power, which your home uses.  The inverter matches the current to the current coming from the public utility and sends the current to the to the main circuit breaker.

3)Utility Meter – something you’re probably used to seeing, these record the electric use of the property for billing by the public utility.  The solar electric current feeds through the meter into the home.  If the home’s electric load is less than the output of the Inverter, the power is fed into the power grid instead!  That’s the best part…

In Pennsylvania, public utilities must offer “Net Metering” to residential customers that generate electricity with systems up to 50 kilowatts (50 kW) in capacity.  “Net Metering” simply describes the process of a homeowner feeding extra electricity into the power grid and that amount being refunded to the owner by the utility at prevailing wholesale electric rates.   So, if the homeowner uses more than the panels produce, they pay for the net usage at regular retail rates.

A well-sized photovoltaic solar system is a critical piece of a “net-zero” home (one that generate zero energy net costs over time).  They are generally the most expensive pieces to install, so check for tax incentives and pencil out the numbers to your satisfaction.