Solar electric, or photovoltaic, systems take the energy from the sun (contained in light particles or photons) and converts it directly into electricity by freeing electrons in the material of a solar cell. Cells are contained in solar panels, usually made of silicon, which conduct the electrical current.
Photo Courtesy of DOE/NREL, Installing PV roof panels
Solar systems on the roofs of homes are like mini power stations. Through equipment in the home, the electricity generally flows into the grid, or electrical system. Through “net-metering” laws in place in many states, utilities are required to buy the power and credit the homeowner. Excess power can even make a meter spin backwards. In places without electrical lines, or where home owners choose to live “off the grid”, solar systems store their electricity in a battery.
Among the benefits of a solar system include:
A rooftop-mounted system can supply much of your home’s electricity, depending on its size and performance. But it’s wise to do everything you can to reduce your home energy use before installing an expensive solar system. A popular saying advises homeowners to eat their conservation and efficiency “vegetables” before enjoying a solar “dessert.”
Conservation and Renewable Energy
Installing a PV system provides the knowledge that you are doing your part to use renewable sources of energy, extending our current energy supplies, while reducing carbon emissions and environmental pollution.
Photo Courtesy of DOE/NREL, Zero energy habitat home; NREL's 2005 Habitat for Humanity house
Deciding if solar is right for you - Siting
Not all rooftops are suitable for solar electric panels. Your roof or other unshaded area needs to face south.
Your roof needs to tilt so it collects good solar energy in all seasons. In the winter the sun will not reach the same angle as in summer. A solar contractor can help you determine the optimum tilt angle.
There are many online calculators and maps to help you decide if solar is right for you.
This map shows solar potential in metro Denver: (http://solarmap.drcog.org/)
This helps you calculate if solar is right for you: Try the Solar Calculator (http://www.solar.coolerplanet.com/Articles/solar-calculator.aspx)
Deciding if solar is right for you -- Financing
Until the last few years, installing a home solar system was a very expensive undertaking that would take many years to pay off. While still costly, a variety of factors have made solar more affordable.
--Many states have Renewable Energy Standards requiring utilities to buy a certain amount of their supplies from renewable sources. They offer incentives and credits to those who help them meet the targets. In Colorado, Xcel must provide 30 percent of electricity from renewable sources by 2020.
Photo Courtesy of DOE/NREL,, Solar hot water system
--Federal and state tax credits and incentives to encourage more solar development have been offered. Explore incentives for your area at the Database of State Incentives for Renewables & Efficiency (http://www.dsireusa.org).
--See our solar financing options sheet for more information.
Equipment and services include:
The PV panels represent perhaps 80% of the total costs. The panels often come with a 20 year performance warranty.
Module mounting systems are used to fasten the panels to your roof.
Direct grid-tie inverters convert the direct current power produced by the PV to alternating current used in the home and send it to the grid through net metering. The inverter represents about 10% of the total cost.
All the necessary wiring.
Questions to ask include:
The solar installation industry is burgeoning and it is wise to do comparison shopping. The good news, however, is that a PV installation is essentially “plug and play” with a minimum of maintenance. There are no moving parts to fail, and the solid state equipment comes with long warrantees.
The National Renewable Energy Laboratory offers many resources on photovoltaics which you can find at: (http://www.nrel.gov/learning/ho_photovoltaics.html)
Many states are now certifying solar installers. The Colorado Solar Energy Industry Association (COSEIA) explains its certification policy here: (http://www.coseia.org/newsite/Certification.html).
Make sure equipment is certified by Solar Rating and Certification Corporation (SRCC): (http://www.solar-rating.org).
References, licensing, insurance
It is always important to speak with previous customers, check with the Better Business Bureau and ask for verification of the necessary licensing and insurance requirements.