A Pro Guide to Installing Solar Panels

Solar panel installation costs have dropped significantly in the past decade. Solar energy systems can make new homes cost more and increase a home’s selling price. The expense of installing solar panels can show returns in 5-10 years with lower power bills, depending on the home’s location and energy needs.

Solar energy systems usually consist of a solar array and other equipment connected to the home and often the local power grid. A solar array is a group of solar or photovoltaic (PV) panels wired together to create an electrical power output. Solar arrays include panels, inverters and mounting racks to complete a solar energy system.

There are three primary types of solar panels, made from different types of solar cells: monocrystalline, polycrystalline or amorphous.

• Monocrystalline cells are comprised of a uniform silicone crystal. Monocrystalline solar panels are the most common and efficient type. They take up less space, withstand high temperatures and last longer than others. They may require higher upfront costs.
• Polycrystalline cells are made up of silicone fragments fused into panels. Polycrystalline solar panels cost less than other types and work best in climates with high levels of sunlight. They generate less power, have slightly shorter lifespans and take up more space than others.
• Amorphous or thin-film solar panels are made from a thin layer of silicon, which allows them to be lighter and more flexible than the other types of panels. They are less efficient, requiring twice the space to provide the same amount of power. They are better suited to recreational vehicles than homes.

A residential solar array also requires a solar power inverter to convert the DC electricity (direct current) produced by the solar panels into AC electricity (alternating current) used by the electrical grid. There are two different types of solar inverters for a residential solar energy system:

• String inverters connect to multiple panels, making them less costly. If one solar panel in the system is damaged or in shadow, it can negatively affect the electrical output of the whole system.
• Microinverters are placed on every panel in an array, making them more independent. Damage to or shade over one panel seldom effects the electrical output of the whole solar array. This design makes them more costly.

Mounting hardware secures solar panels to the roof or ground.

• Fixed mounting racks remain in the same pre-set position. They are less costly to install and often require less upkeep.
• Tracking mounts move or can be adjusted for height and angle to follow the sun’s changing path. They can be more expensive and require more upkeep but allow customers to maximize the amount of available sunlight.

Solar panel batteries store electricity for use after sunshine hours. Homes on the grid may not need solar batteries, as they can draw energy from the grid at night. Homes off the grid usually need solar batteries. These are the four main types of solar batteries.

• Lead acid batteries are reliable and less expensive but require frequent maintenance.
• Lithium ion batteries have long lives and require no maintenance but are more expensive.
• Nickel cadmium batteries can operate at high temperatures and are most popular for commercial-scale projects.
• Flow batteries are the largest and most expensive batteries and are primarily used for large-scale battery storage.

Most solar panel kits feature one of the two inverters, as well as essential solar power accessories such as batteries, solar battery chargers, charge controllers and cables.

The cost of professional solar panel installation relies on a range of factors, including the number of solar panels needed. Most single-family homes need 15-19 solar panels, depending on their energy consumption and the amount of sunlight the homes receive. The larger the home, the more solar panels needed.

When adding solar panels to an existing home, you can determine the customer’s monthly energy consumption based on their power bills. For the most accurate estimate, divide the annual usage by 12 for the average monthly energy usage. (Be sure to use just the electricity costs in utility bills that include both power and water.)

Another major factor is the amount of sunlight the home receives, known as peak sun hours. A peak sun hour is defined as an hour of sunlight that generates an average of 1,000 watts of energy per square meter.

States with the highest peak sun hours are Arizona (5.25-5.75 and more), New Mexico (5-5.75 and more) and Texas (4.5-5.75 and more). Peak sun hours vary by season and climate.

Small branches, thin vent pipes, skylights and other roof obstructions usually do not cast enough shade to limit the energy of peak sun hours. More extensive shade from tree canopies or neighboring buildings can limit the effectiveness of solar panels.

The formula for calculating how many solar panels a home needs = (Monthly energy usage ÷ Monthly peak sun hours) ÷ Solar panel output

For example, take the case of a home that uses an average of 1,200 kilowatt-hours of electricity a month. Suppose that it is in an area that gets 150 peak sun hours a month (or five peak sun hours per day).

1200 ÷ 150 = 8, meaning the home needs an 8-kw solar energy system.

Then, suppose you’ve chosen solar panels that can generate 0.4 kw each.

8 ÷ 0.4 = 20, meaning the home will need 20 solar panels in its system.

Solar panels and other equipment usually make up about 50% of the cost of a residential solar energy system. The remaining costs include labor, taxes, permitting and administrative fees. These can vary greatly depending on such factors as area labor costs and the demands of each job. For instance, installations that require upgrading the home’s electrical panel will require the services of an electrician.

Pro Tip: Homes with solar panels installed by December 31, 2025, will qualify for the Federal Solar Investment Tax Credit, which represents 30% of the total cost of the system. The location may have access to additional rebates, state tax credits and other cost benefits.

Installing solar panels on existing homes begins with choosing the placement on the roof or other part of the property. Some Pros determine the suitability of a house for solar panels using “the three S” method, for “shade,” “space” and “South:”

• Does the roof receive significant shade from nearby trees or structures?
• Does the roof have enough space for the solar panels the home needs?
• Does the roof face South?

If the roof is not suitable, homes can be equipped with ground-mounted solar arrays. Ground-mounted panels can be installed anywhere with good sun exposure and enough open space. A minimum of 350 square feet is usually required.

Installing solar panels requires the following steps:

• Plan the solar energy system based on the home’s size, location and energy needs.
• Measure, cut and assemble the support structure for the solar array.
• Install solar modules, panels and support structures according to local building codes and standards.
• Connect the solar power inverter to the electrical system.
• Apply weather sealant to the equipment being installed.
• Activate and test solar energy systems.

Solar installers should be certified to work with electricity at high elevations according to best safety practices:

• Electrical safety practices include switching off the power before wiring, wearing protective gear and more.
• Height-related safety practices include wearing safety harnesses, securing tools to avoid dropping them and more.

Pro Tip: Solar panels are most effective on unshaded, south-facing roofs with a 15-40-degree slope.

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