Solar Installation FAQ's:
How does a solar cell work?
What is a PV system?
What are the different types of PV systems?
What are the components of a PV system?
What is net metering?
How are solar panels mounted?
Can I install a system myself?
What are the tax benefits?
How does a solar cell work?
A solar cell takes advantage of the "photovoltaic effect," a process where the energy contained in light is converted into electricity. Special semi-conducting materials, one negative layer and one positive layer, are sandwiched together forming a junction between them. As photons of light energy are absorbed by negatively charged free electrons in the top layer, this causes them to flow through the junction to the positive layer below, creating electrical current.
The earliest solar cells were only able to convert 1-2% of sunlight energy into electrical energy. Today's more efficient designs are able to convert up to around 18% of the sunlight energy into electricity, and price per watt has come down. You can now easily harvest the free energy from the sun to reduce your power bills and help to reduce pollution at the same time.
What is a PV system?
A PV, or photovoltaic, system uses a number of solar cells and other connected components to generate electricity. Systems range from a few watts of power that can charge your cell phone or laptop all the way up to hundreds of thousands of watts that can power a commercial building or industrial plant.
What are the different types of solar systems?
The simplest type of system is a "grid-tie" system that connects your solar panel array directly to the electrical grid using a device called an inverter. The inverter conditions the DC power from the solar cells into AC power that is compatible with the utility grid.
More complex is a grid-tie system with battery backup that incorporates energy storage in the form of a battery to keep "critical load" circuits working in the event of a utility outage. If an outage occurs, the unit disconnects from the utility and supplies power until the utility returns service.
It is also possible to go completely "off grid" where you provide all of your energy needs from a Photovoltaic array or other renewable resources, however this requires careful power management. Often many loads such as lighting or well pumps will be converted to run on DC power rather than AC to increase efficiency. Heavy loads such as air conditioning, large motors, etc., must be factored into overall system sizing.
What are the components of a PV system?
What is net metering?
Utility companies are required to permit the connection of PV systems to their power delivery lines. When your PV system generates more power than is being used, the excess electricity is fed back to the grid... your electric meter may acatually run backwards.
How are solar panels mounted?
Most systems are either roof mounted, ground mounted, or pole mounted. The method used is determined by the installation site and the customers preferences. Particular attention must be paid to roof structure and weather sealing of roof penetrations. Most typical PV systems produce 5- to 10-watts per square foot of array area depending on the technology of the cells.
A typical 2-kW system will need from 200-400 square feet and additional area must be allowed for access space to service and maintain the array.
Can I install a system myself?
Some enthusiasts have successfully installed their own systems, however this is not recommended for a number of reasons. The foremost reason is safety. Performing this task is not a trivial undertaking since it involves working with potentially lethal voltages, and requires specialized knowledge such as NEC and local electrical codes and IEEE 929-2000 practices for interfacing to the utility grid.
One common pitfall that amateurs experience is improper wire sizing and switch / disconnect planning. This could lead to failure to pass required inspections, or even fire hazards if a system is not installed properly.
It is best to deal with a professional contractor who has had training and experience on electrical and PV systems. A good contractor can assure that the proper permits and approvals are handled and can select proper components and wiring systems that are compatible with your electrical system and meet your power needs.
What are the tax benefits for installing a PV system?
There are a number of tax incentives and credits available to offset the costs of installing alternative energy. Check our tax information page for more information.
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