More and more homeowners are working with solar contractors and using residential solar power as a way to lower energy expenses and reduce their carbon footprint.

How to choose the best solar system and solar contractor is a challenge for customers.  How to select a solar system for home use is easiest when partnering with a solar contractor.

There are many factors that homeowners need to consider, including questions about their solar energy budget, household energy use, taxable income, and the location and orientation of the house. Solar contractors need to be prepared to address these questions since a salesperson’s job always involves a process of educating the consumer.

Cost Considerations: Any homeowner must weigh the costs versus the benefits of having solar power.  Here are some issues solar contractors and their salespeople should address with the customer:

• By examining the utility bills, know what the household’s energy use patterns are.
• How much energy the house currently consumes and how much of that wattage can be offset with solar.
• If the customer plans to live in the house long enough to recoup the investment in solar.
• What the household’s future energy needs are likely to be.
• If the house is significantly shaded by trees, the homeowner will need to pay to have some removed.
• With the energy cost savings from solar power, how long will it take to recoup the investment?
• Investigate federal, state, local and power company tax benefits or rebates. These can lower the cost of solar considerably.

System Size: Many homeowners don’t understand the relationship of solarpanel size to wattage and energy output – and to cost. Solar contractors should be prepared to explain some of the facts that every customer should understand.

• The price of the solar panel is related to its size and wattage. Larger panels generate more wattage.
• The main issues are that the solar system has sufficient wattage to power the household appliances and that the panels will physically fit onto the house’s roof.
• The type of solar cell helps determine the size and cost of the panel. Film panels are less expensive than monocrystalline and polycrystalline panels, but they need more roof space
• A 100 watt solar panel will generate 100 watts of electricity an hour while a 200 Watt panel will produce 200 watts per hour. So, a 200 watt panel should cost approximately twice a 100 watt.
• If a system will be stand-alone, it must be capable of producing all the electricity a household needs.  This is less important if a system will be connected to the grid.
• The larger the system, the less it typically costs per watt.

Types of Solar Panels: Customers should understand that there are three main types of solar cells which vary in efficiency and price. No panel is 100% efficient, but some are better than others at converting their absorbed solarenergy into electricity. Solar constractors should be prepared to describe the differences among kinds of panels and the trade-offs in efficiency and cost.

• Monocrystalline silicon is the most efficient and can provide more energy with smaller panels, but this type is also the most expensive.
• Polycrystalline or Multicrystalline silicon isn’t as efficient as monocrystalline, but offers a good balance of efficiency and cost. Innovations in technology are always improving this type’s performance.
• Thin-Film silicon is the least efficient and the least expensive. Homeowners will need larger panels to generate the same amount of energy as a comparable polycrystalline or monocrystalline system.

Components of a Solar Power System: Homeowners should understand that there is more to the solar system than just the panels. Solar contractors should explain the different components and how they work together.

• Panels: These vary in size and positioning depending on the household’s power needs, and the location and orientation of the house.
• Inverter:  Electricity that comes from solar power is DC (direct current) while most households operate on AC (alternating current). Power flows from the solar panels into the inverter, which converts the energy into current the house can use.
• Batteries: If a household is not tied to the grid, it will need deep-cycle batteries to store electricity for nighttime and cloudy days. Nickel-cadmium batteries are the best kind, though the most expensive.
• Monitors:  Some solar contractors or utility companies provide households with displays that show their panels’ output and energy usage – or with programs that allow the homeowner to view the information on the internet.
• The Rest of the System: Like any other electrical system, solar systems require junction boxes, wiring, grounding and over-current protection devices, outlets, switches, etc.

The Lifetime of the System: Another factor in choosing a solar energy system is its expected lifetime or durability. Since consumers are amortizing the cost of the system over several years, it’s important they install a system that will last long enough to recoup the expense – and then some.

• Brand:  Homeowners need to a select reputable brand. Solar is a relatively new industry and some companies don’t make top-quality products.
• Durability: Most solar panels last 30 years – although they decrease in efficiency as they get older.
• Warranty: Reputable companies usually guarantee their products for at least 25 years. If a panel only has a ten year warranty, it should pay for itself in fewer than ten years. Consumers should choose established solarcontractors. A warranty isn’t any good if the company has gone out of business.
• Inverters and batteries don’t last as long as panels, so customers should expect to replace those sooner.
• Repairs: Choose solar contractors that can provide any necessary service that is covered by the warranty.

Advice for Choosing a Solar Contractor from the U.S. Department of Energy

When choosing a contractor, ask yourself the following questions:

Has the company installed grid-connected PV systems? If not, has it installed grid-independent (or stand-alone) PV systems?

Experience in installing grid-connected systems is valuable because some elements of the installation—particularly interconnection with the local utility—are unique to these systems. However, a competent company with off-grid PV experience should not be eliminated just because it has not yet installed grid-connected PV systems. Experience with off-grid systems is valuable too, because grid-independent systems are more technically complex than grid-tied systems.

How many years of experience does the company have installing PV systems?

A contractor who has been in business a long time probably understands how to work with customers and to compete effectively with other firms. Additionally, he/she will probably be aware of the latest code and permitting issues surrounding the installation of PV systems.

Is the company properly licensed or certified?

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 acontractor 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 where you live 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. Special knowledge can be demonstrated through certification by solar industry and/or trade associations.

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 where they live for information on how to evaluate contractors. The Better Business Bureau is another source of information.