How do Photovoltaic Systems (PV) Work?

Photovoltaic (PV) systems, Grid-tie, Stand-alone and Hybrid, are solar energy systems that produce electricity directly from sunlight.  They produce dependable, clean energy without consuming fossil fuels.  The main advantages of PV technology are:

Above is a simple illustration of a basic PV system. An actual system may have more components, depending on whether the customer wishes to connect to the grid, in which case safety mechanisms must be installed, (i.e. inverter with islanding protection and lockable ac disconnects, etc). A customer may also wish to add a battery system for nighttime power, which also has safety and interconnection requirements. As a licensed solar contractor I can assist you in determining what will work best for your situation and needs.

Grid-Tied Systems

The key components for a grid-tied system are:

• Photovoltaic panels
• Mounting system
• Inverter
• Auto Disconnect

In the Grid-tie system, which is the most advantageous for homeowners, the electricity the solar panels generate is fed directly into your local utility company lines. During the day, your system produces enough electricity to supply part or all of your electricity needs. Any excess power is sent back to the grid and either sold back to the utility company at cost, or your meter simply runs backward, lowering your electric bill. At night or when you need more power than you are producing, that power is supplied by your utility. With this system a battery bank is not required, which lowers costs. 

In our area we have many part-time residents.  In the homeowner’s absence the PV system is producing electricity that goes back to the grid which will build credit on your bill for those months when the home is occupied and electric use is at its peak.

Stand Alone Systems

A Stand-alone system uses an array of PV modules to supply your total electric needs. During sunny days, excess energy is stored in a battery bank. That energy is then available for use at night or on cloudy days. PV systems are sized to keep you supplied even during the short days of winter or when it’s cloudy for few days in a row. The advantage of this system is that it is completely independent of traditional energy sources and a fully functional system can be installed almost anywhere. One of the disadvantages is the added cost of the battery bank.

Hybrid Systems

Hybrid systems use other energy generation sources in conjunction with PV. They are a great option for areas that don’t have consistently sunny days. Wind generators are a good option in many areas. It is also possible to install a gasoline, diesel, or propane generator. A well-designed system configured in this way can supply all your power needs by running a generator just a few hours every day or two. This can save on wear, tear, fuel, and maintenance on your generator, as well as the annoyance of generator noise. The advantages of the Hybrid systems are their lower costs and their high margin of flexibility.