By DAN YECHOUT January 15, 2010
Solar power is a major investment that needs to be tailored to your house and your lifestyle.
Designing the system is a complex process best tackled in detailed discussions with a knowledgeable installer. Moreover, it’s a long-term investment. Because the array may produce power for at least 30 years, you’ll want to establish a solid relationship with your installer. Follow these tips when searching for a system installer. Though these guidelines deal primarily with installers of solar electric systems, they can also be used when looking for a solar thermal installer.
Designing Your System
Your installer can help you figure out the optimum size for your system. it will depend on the rate at which you use electricity, your budget, the size and shape of your roof and the incentives offered by your state and utility. For instance, in some areas, incentives won’t cover systems of more than 2 kilowatts.
Begin the design process with a review of the electricity usage history for the home. if past bills are not on file, get an account history from your utility company. Consider whether lifestyle changes will affect your utility bills in the future. are you adding a kid to the household or sending one off to college? Setting up a home office? If you plan to add air conditioning, an electric car or more people to the household, estimate the additional future consumption.
You’ll need to understand the electric rate structure of your local utility. Your utility company may bill and pay for straight kilowatt-hour (kWh) rates, inverse-tiered rates or time-of-use rates.
Where straight kWh net-meter rates are offered, the utility company typically buys all your solar-power generation at the same retail rate, up to 100 percent of your consumption. In these cases, you can size your photovoltaic (PV) system to cover up to 100 percent of your expected energy use. Beyond 100 percent, the utility company often buys the surplus at a lower wholesale rate. Because PV systems tend to be less expensive per watt as they grow larger, the optimum investment in a straight-kWh rate structure is often to generate just under 100 percent of your consumption. Some utilities may offer a feed-in tariff, where the solar production is metered separately and the purchase rate is not related to your consumption.
Under an inverse-tier rate structure, the utility company charges more for higher amounts of usage, similar to a tax bracket structure. For example, the utility may charge a base rate for usage under 300 kWh per month, a higher rate for the next 200 kWh, and so on. Under an inverse-tier structure, the PV system can help you stay in lower-tier rates. Your best investment may be to size the PV system to get you into the low-tier rates but not necessarily cover 100 percent of your usage.
In time-of-use structures, the utility company charges more for electricity during peak consumption periods. Peak consumption typically occurs in the afternoon when people are working and running air conditioners. Under a time-of-use structure, PV panels that face more southwesterly will generate electricity when electricity is most expensive.
Finally, estimate the remaining life of your roof. Your PV system should be in place for at least 20 years, so you want to make sure your roof has that much life left as well. Otherwise, you will be facing an additional expense to remove and reinstall the PV system when it is time to reroof.
An experienced local installer will already have done the appropriate calculations for other customers and can walk you quickly through this exercise.
Researching Solar Installers
Get proposals from three different companies and see how each handles the design process. Personal referrals are your best source for finding a quality contractor.
Ask around in your community about which solar companies are well respected. Do an internet search for solar in your town and see which companies have been in the news for doing quality work in your area. it may help to attend a meeting of your local American Solar Energy Society chapter — you’ll meet people who’ve already purchased solar arrays for their homes and can ask them about their experiences.
When interviewing solar contractors, focus on experience and stability. How many residential systems have they installed in your area? Companies with the most local experience will have the best recent knowledge of the rebate process, building codes, homeowner’s association restrictions and financing options. Get a list of as many of the contractor’s installations as possible and go look at them.
If appropriate for your climate, ask how the design will shed snow. Ask if rodent damage or bird nesting issues will need to be dealt with.
Many solar installers require a down payment to commence the project. This is fine; however, you may want to ask if the down payment can be waived for a financing charge. If the installer does not offer this option, it may indicate an unsound cash-flow situation for the company and questionable long-term stability.
Also ask how many projects the installer has in its backlog. While it may be tempting to select an installer who can be at your house installing panels the following week, a short project backlog may indicate that the company is struggling to get work (similar to a restaurant that has no diners).
Find out how many electricians and North American Board of Certified Energy Practitioners (NABCEP)-certified installers the company has on call. This will shed light on the company’s expertise and commitment to maintaining competent employees. Will all the work be done by the company’s own employees? If the company uses sub-contractors, make sure you read the contract to know who is responsible for warranties or work left unfinished.
Ask how the company handles service issues. Do they have a dedicated service department? What turnaround time will they guarantee for service calls? Also ask how they will guarantee the performance of the PV system. For example, if your system has some partial shade, what recourse will you have if the system does not produce the electricity that the installer predicted?
In case of a system failure, how quickly do they guarantee to have the system up and running again? Installers in the same market often offer the same warranty term; however, what is covered under the warranty can vary dramatically.
Anyone can sell solar panels. it’s important to choose a company that will stand by its product and ensure you realize the fruits of your investment. The solar installers with the best warranty and service may cost more up front, but they can save you money in the long run.
Each proposal should list the make and model of the PV modules, mounting system, inverter and other electronics. It should show total component cost, sales tax, labor charge, gross system cost and the estimated effect of local rebates and the federal tax credit. Be careful of the installer’s interpretation of the federal tax credit as it applies to local rebates. Typically, the federal tax credit is applied after rebates are deducted from the system cost. If the federal tax credit is applied to the gross system cost, any rebates may be subject to federal income tax. Ask whether the cost includes everything required to install and commission the PV system. Certain fees, such as permits and roofing costs, may not be included by some installers. Find out how much these may be. Also ask how any cost changes during the project will be handled, and how the installer will minimize your exposure if the system costs more than expected.
When comparing proposals, it’s easy to overlook the components and just focus on how much power you get for your dollar. This can be a mistake. Most PV panels offer 20- to 25-year warranties, and inverters offer 10-year warranties.
A warranty is only as good as the company behind it. Research the PV panel and inverter manufacturers. Determine if they are established, financially sound companies that are dedicated to the PV business and are likely to honor their warranties years down the road. If environmental stewardship is one of your reasons for going solar, consider how environmentally responsible the product manufacturers are. Established companies should publish a corporate responsibility report.
Making the Purchase
When you are ready to select your solar installer, there are a few final details to be discussed before contract signing. Determine the expected installation start and finish dates as well as the expected system turn-on date. Local utility rules often cause a delay between system completion and turn-on, and the installer should set your expectations appropriately. If local rebates are available, ask about the rebate process and how the installer can help you navigate the system.
Installing the System
PV installations by a competent contractor are typically hassle-free for the homeowner. A typical roof installation takes two to three days but may be longer for a large system or on a steep or complex roof. Once the PV system is complete, the local jurisdiction will inspect the installation for local building code and National Electric Code compliance. The installer will then make any corrections required by the inspector. Finally, the net meter will be installed by the utility company, and the system can be turned on.
Once your system is operational, the installer should conduct an orientation to make sure you understand how to read the inverter display and any remote monitoring software you may have purchased. The installer will show you how to identify a system outage, which is usually indicated via the inverter display. You’ll learn how to track production to make sure the system is generating the predicted power. You should also receive a system manual which contains the electrical diagram for the system (in case someone else needs to work on the system in the future), component serial numbers, component warranties and product manuals.
Servicing the System
The most common service issue with a PV system is inverter failure. In the event of failure under warranty, the installer should service or replace the inverter at the manufacturer’s expense. Be sure to check in advance whether roof leaks are covered under the installer’s warranty. While PV panels are tested for hail resistance, hail damage is not covered under the manufacturers’ warranties and would need to be covered with a homeowner’s insurance claim. Before purchasing a PV system, contact your homeowner’s insurance company and determine the additional cost, if any, to insure the system.
Dan Yechout is director of sales at Namasté Solar (namastesolar.com) in Boulder, Colo. He holds a bachelor’s in electrical engineering from Colorado State University and is a NABCEP-certified PV installer. He has designed more than 150 successful PV systems.