Selecting a photovoltaic provider

Many electrical contractors, although proficient in typical electrical contracting work, might not have expertise in PV or residential roof-mounting techniques.

Who sells and installs PV systems? In some areas, finding a PV provider can be as simple as picking up the telephone directory and looking under “Solar Energy Equipment and Systems—Dealers.” However, many of the listings are solar water-heating companies and many companies might not be experienced in PV system design or installation. Similarly, many electrical contractors, although proficient in typical electrical contracting work, might not have expertise in PV or residential roof-mounting techniques. How do you identify solar electric system providers? Here are several suggestions.

• Check the Source Guide for renewable energy businesses (including PV) by name, product type, business type, and location: http://energy.
• Contact the Solar Energy Industries Association (SEIA) at 202-628-7745 for a list of solar service providers.
• Contact your utility company to see which vendors it might recommend.
• Conduct a search on the Internet. Reputable, professional contractors with experience in PV systems are the best choice for the actual installation.

How do you choose among PV providers?
Compile a list of prospective PV providers. (Those closest to you should have the lowest travel costs). Contact these providers and find out what products and services they offer. The following questions may give you a good sense of their capabilities:

Has the company installed gridconnected PV systems? If not, has it installed grid-independent (or stand-alone) PV systems? Experience in installing gridconnected systems is valuable because some elements of the installation— particularly interconnection with the local utility—are unique to these systems. Because gridconnected systems are relatively uncommon, however, most contractors with PV experience have worked only on stand-alone systems. So, they have experience with all aspects of PV system installation except connection with the utility grid. However, a competent company with PV experience should not be eliminated just because it has not yet installed grid-connected PV. Experience with off-grid systems is valuable, because grid-independent systems are more technically complex than grid-tied systems.

How many years of experience does the company have installing PV systems?
This issue speaks for itself: A contractor who has been in business a long time probably understands how to work with customers and to compete effectively with other firms.

Is the company properly licensed?
PV systems should be installed by an appropriately licensed contractor. This usually means that either the installer or a subcontractor has an electrical contractor's license. Your State Electrical Board can tell you whether a contractor has a valid electrician's license. Local building departments might also require that the installer have a general contractor's license. Call the city or county you live in for additional information on licensing.

A solar rebate program may require that, in addition to being properly licensed, installers must demonstrate that they have special knowledge about installing PV systems. This special knowledge may be demonstrated in one of the following ways:

• Possession of a solar contractor specialty license, issued by a local building jurisdiction, that recognizes— through testing or other means—special knowledge of PV systems
• Certification in PV systems by a group such as the state chapter of SEIA
• A letter from the PV system manufacturer stating that the installer has the experience and training needed to install the system properly.

Does the company have any pending or active judgments or liens against it?
As with any project that requires a contractor, due diligence is recommended. Your state electrical board can tell you about any judgments or complaints against a state-licensed electrician. Consumers should call the city and county they live in for information on how to evaluate contractors. The Better Business Bureau is another source of information.

How do you choose among competing bids?
If you decide to get more than one bid for the installation of your PV system (always a good idea), make sure that all bids are made on the same basis. For example, a bid for a system mounted on the ground is usually very different from another bid for a rooftop system.

Similarly, some PV modules generate more electricity per square foot than others. Bids should clearly state the maximum generating capacity of the system (measured in watts or kilowatts). If possible, have the bids specify the system capacity in “AC watts” under a standard set of test conditions, or specify the output of the system at the inverter. Also request an estimate of the amount of energy that the system will produce on an annual basis (measured in kilowatt-hours).

Because the amount of energy depends on the amount of sunlight— which varies by location, season, and year to year—it’s unlikely the contractor will quote a specific figure, but a range of ±20% is realistic. Bids also should include the total cost of getting the PV system up and running, including hardware, installation, connection to the grid, permitting, sales tax, and warranty.

Your warranty is a very important factor for evaluating bids. A solar rebate program may require that systems be covered by a two-year parts-and-labor written installation warranty, for example, in addition to any manufacturers' warranties on specific components. The installermay offer longer warranties. Also, ask yourself, “Will this company stand behind the full-system warranty for the next two years?”

Is the lowest price the “best deal”?
It might not be. You generally get what you pay for, and it's possible that a low price could be a sign of inexperience. Companies that planto stay in business must charge enough for their products and services to cover their costs, plus a fair profit margin. Therefore, price should not be the only consideration, and quality should