A Quick Guide to Solar Electricity

What is solar electricity?

Solar electric or photovoltaic technology converts sunlight directly into electricity. You may be more familiar with photovoltaic cells as solar cells that power watches and calculators. But photovoltaic can do much more. It can provide electricity for your home and provide the opportunity for you to take advantage of net metering.

How do solar electricity or photovoltaic systems work?

Sunshine is converted into electricity by using solar panels (also called photovoltaic or photovoltaic panels). The solar modules produce DC, or direct current, when exposed to sunlight. Our home and workplaces use AC, or alternating current. A device called an inverter converts the DC electricity generated by the photovoltaic array to AC electricity that is usable in your home, as well as protects you from unsafe operating conditions that could damage equipment or be harmful. In addition, if your photovoltaic system produces more electricity than your home requires, you can “net meter” the excess solar energy back to Rocky Mountain Power and receive a credit on your electric bill.

Why use photovoltaic?

The sun generates an abundance of clean energy that is largely unused for residential and non-residential purposes. Why not tap into this plentiful resource of clean energy? Photovoltaic preserves the earth’s finite fossil-fuel resources – coal, oil and natural gas – which are used to generate electricity. Photovoltaic also reduces air and noise pollution associated with electricity generated from those sources. In addition, many people value the independence gained by producing the energy that their home and families will use and appreciate knowing that their efforts are also helping to preserve the environment. Recent technological breakthroughs, combined with our incentive program, have greatly reduced the cost of photovoltaic ownership. Photovoltaic system reliability and durability are outstanding – typical photovoltaic systems may last 40 years with minimal maintenance.

What happens if the sun doesn’t shine?

Your photovoltaic system will continue to produce electricity during cloudy weather, although the total amount produced will be less.

What does a typical photovoltaic system look like?

A typical photovoltaic panel consists of solar cells connected electrically to form a module that can measure two to four feet wide and four to six feet long. Some solar modules look just like traditional roof shingles. Many interconnected photovoltaic modules are called an array. Other typical features of a photovoltaic system are an inverter, which changes the electricity produced by the photovoltaic system from DC to AC, the type of electricity used in your home.

Is my home right for a photovoltaic system?

A photovoltaic system needs unobstructed access to the sun’s rays for most, or all of the day, throughout the year. Photovoltaic panels are relatively unaffected by changing weather. In fact, some photovoltaic cells actually work better at colder temperatures. Photovoltaic modules are angled to catch the sun, not snow, so any snow that does collect melts quickly. To maximize the energy production of photovoltaic electricity, photovoltaic systems are installed on a southern exposed roof and mounted parallel with the roof at a 30 or 40-degree roof pitch with no shading. However, roofs that face east or west may also be acceptable. Photovoltaic panels should have their surfaces exposed to the sun’s rays for most or all of the day, with minimal or no shadows from trees, chimneys and roofs between 9 a.m. and 4 p.m.

Can my home accommodate a photovoltaic system?

The amount of space needed by a photovoltaic system is based on the output of the photovoltaic system and the type of photovoltaic system installed. Most small systems require as little as 100 square feet (for a small "starter" system) and up to as much as 1,000 square feet for larger systems. A typical 1 kilowatt (kW) system should occupy approximately 100 square feet. If your location limits the physical size of your system, you may want to install a system that uses more efficient photovoltaic modules. Greater efficiency means that the module produces more electricity from a smaller area.

Do I need to be concerned with the condition of my existing roof?

A photovoltaic system can be installed on any well-structured roof. Typically asphalt shingles are easiest to work with, while slate or tile is the most difficult. If your roof is older and needs to be replaced in the very near future, you may want to replace it at the time the photovoltaic system is installed to avoid the future cost of removing and reinstalling your photovoltaic system. Photovoltaic systems are also available that integrate photovoltaic cells into the roofing materials themselves. This allows the roof to act as the photovoltaic collecting device and serves as an option when replacing a roof or designing and/or building a new home. An additional benefit of an integrated photovoltaic system is its ability to offset the cost of roofing materials.

How much does a photovoltaic system cost?

The total cost of a photovoltaic system includes the cost of the photovoltaic equipment and installation. Your photovoltaic system’s cost will depend on a number of factors, including system size and the energy efficiency of your home, whether the home is under construction and whether the photovoltaic is integrated into the roof or mounted on top of an existing roof. The cost also varies depending on the photovoltaic system rating, size, manufacturer, retailer and installer. Small scaled photovoltaic systems with built in inverters that produce about 1 kW of power may cost about $10 to $12 per watt ($10,000-$12,000) installed. These small systems will offset only a small fraction of your electricity bill. At the high end, a 5 kW system that will completely offset the energy needs of many conventional homes may cost $7 to $10 per watt ($35,000-$50,000). These prices are just rough estimates; your costs will depend on your system's configuration, your equipment options and other factors.

How much electricity does a photovoltaic system make?

A 1 kW system that is properly installed and positioned can typically generate approximately 2,000 kW hours (kWh) per year. Using a $.10 per kWh rate, that equates to $200 worth of electricity per year.

What incentives are available to help reduce the cost?

Our program currently offers incentives to our Utah customers that can significantly reduce the cost of purchasing a photovoltaic system. They offer direct incentives of $2.00 per watt toward the installation of a residential photovoltaic system up to 3 kW, or a maximum incentive of $6,000. Non-residential customers can install a photovoltaic system up to 15 kW and receive a maximum incentive of $30,000. These incentives are scheduled to be available through January 31, 2010, subject to available funding. Additional tax credits may be available to further reduce the photovoltaic system cost, please see your tax accountant for further details.

In addition, you can take advantage of net metering.

Homeowners can use solar power to run their electric utility meters backward and credit excess energy production back to Rocky Mountain Power. The table below provides a breakdown of estimated costs, incentives and the value of photovoltaic generated electricity for a small 1 kW system:

Sample Estimate for a 1 Kilowatt photovoltaic System

Who can I contact for more information?

Rocky Mountain Power Solar Incentive Program
Phone: 1-866-344-9802
E-mail: solar@rockymtnpower.net